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• Instanced drawing with OpenGL ES 2.0

  - by Mårten Wikström

  In short: Is it possible to use the gl_InstanceID built-in variable in OpenGL ES 2.0? And, if so, how? Some more info: I want to draw multiple instances of an object using glDrawArraysInstanced and gl_InstanceID, and I want my application to run on multiple platforms, including iOS. The specification clearly says that these features require ES 3.0. According to the iOS Device Compatibility Reference ES 3.0 is only available on a few devices (those based on the A7 GPU; so iPhone 5s, but not on iPhone 5 or earlier). So my first assumption was that I needed to avoid using instanced drawing on older iOS devices. However, further down in the compatibility reference document it says that the EXT_draw_instanced extension is supported for all SGX Series 5 processors (that includes iPhone 5 and 4s). This makes me think that I could indeed use instanced drawing on older iOS devices too, by looking up and using the appropriate extension function (EXT or ARB) for glDrawArraysInstanced. I'm currently just running some test code using SDL and GLEW on Windows so I haven't tested anything on iOS yet. However, in my current setup I'm having trouble using the gl_InstanceID built-in variable in a vertex shader. I'm getting the following error message: 'gl_InstanceID' : variable is not available in current GLSL version Enabling the "draw_instanced" extension in GLSL has no effect: #extension GL_ARB_draw_instanced : enable #extension GL_EXT_draw_instanced : enable The error goes away when I specifically declare that I need ES 3.0 (GLSL 300 ES): #version 300 es Although that seem to work fine on my Windows desktop machine in an ES 2.0 context I doubt that this would work on an iPhone 5. So, shall I abandon the idea of being able to use instanced drawing on older iOS devices?

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• Using 3G/UMTS in Mauritius

  After some conversation, threads in online forum and mailing lists I thought about writing this article on how to setup, configure and use 3G/UMTS connections on Linux here in Mauritius. Personally, I can only share my experience with Emtel Ltd. but try to give some clues about how to configure Orange as well. Emtel 3G/UMTS surf stick Emtel provides different surf sticks from Huawei. Back in 2007, I started with an E220 that wouldn't run on Windows Vista either. Nowadays, you just plug in the surf stick (ie. E169) and usually the Network Manager will detect the new broadband modem. Nothing to worry about. The Linux Network Manager even provides a connection profile for Emtel here in Mauritius and establishing the Internet connection is done in less than 2 minutes... even quicker. Using wvdial Old-fashioned Linux users might not take Network Manager into consideration but feel comfortable with wvdial. Although that wvdial is primarily used with serial port attached modems, it can operate on USB ports as well. Following is my configuration from /etc/wvdial.conf: [Dialer Defaults]Phone = *99#Username = emtelPassword = emtelNew PPPD = yesStupid Mode = 1Dial Command = ATDT[Dialer emtel]Modem = /dev/ttyUSB0Baud = 3774000Init2 = ATZInit3 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0Init4 = AT+cgdcont=1,"ip","web"ISDN = 0Modem Type = Analog Modem The values of user name and password are optional and can be configured as you like. In case that your SIM card is protected by a pin - which is highly advised, you might another dialer section in your configuration file like so: [Dialer pin]Modem = /dev/ttyUSB0Init1 = AT+CPIN=0000 This way you can "daisy-chain" your command to establish your Internet connection like so: wvdial pin emtel And it works auto-magically. Depending on your group assignments (dialout), you might have to sudo the wvdial statement like so: sudo wvdial pin emtel Orange parameters As far as I could figure out without really testing it myself, it is also necessary to set the Access Point (AP) manually with Orange. Well, although it is pretty obvious a lot of people seem to struggle. The AP value is "orange". [Dialer orange]Modem = /dev/ttyUSB0Baud = 3774000Init2 = ATZInit3 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0Init4 = AT+cgdcont=1,"ip","orange"ISDN = 0Modem Type = Analog Modem And you are done. Official Linux support from providers It's just simple: Forget it! The people at the Emtel call center are completely focused on the hardware and Mobile Connect software application provided by Huawei and are totally lost in case that you confront them with other constellations. For example, my wife's netbook has an integrated 3G/UMTS modem from Ericsson. Therefore, no need to use the Huawei surf stick at all and of course we use the existing software named Wireless Manager instead of. Now, imagine to mention at the help desk: "Ehm, sorry but what's Mobile Connect?" And Linux after all might give the call operator sleepless nights... Who knows? Anyways, I hope that my article and configuration could give you a helping hand and that you will be able to connect your Linux box with 3G/UMTS surf sticks here in Mauritius.

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• Memory allocation problem C/Cpp Windows critical error

  - by Andrew

  Hi! I have a code that need to be "translated" from C to Cpp, and i cant understand, where's a problem. There is the part, where it crashes (windows critical error send/dontSend): nDim = sizeMax*(sizeMax+1)/2; printf("nDim = %d sizeMax = %d\n",nDim,sizeMax); hamilt = (double*)malloc(nDim*sizeof(double)); printf("End hamilt alloc. %d allocated\n",(nDim*sizeof(double))); transProb = (double*)malloc(sizeMax*sizeMax*sizeof(double)); printf("End transProb alloc. %d allocated\n",(sizeMax*sizeMax*sizeof(double))); eValues = (double*)malloc(sizeMax*sizeof(double)); printf("eValues allocated. %d allocated\n",(sizeMax*sizeof(double))); eVectors = (double**)malloc(sizeMax*sizeof(double*)); printf("eVectors allocated. %d allocated\n",(sizeMax*sizeof(double*))); if(eVectors) for(i=0;i<sizeMax;i++) { eVectors[i] = (double*)malloc(sizeMax*sizeof(double)); printf("eVectors %d-th element allocated. %d allocated\n",i,(sizeMax*sizeof(double))); } eValuesPrev = (double*)malloc(sizeMax*sizeof(double)); printf("eValuesPrev allocated. %d allocated\n",(sizeMax*sizeof(double))); eVectorsPrev = (double**)malloc(sizeMax*sizeof(double*)); printf("eVectorsPrev allocated. %d allocated\n",(sizeMax*sizeof(double*))); if(eVectorsPrev) for(i=0;i<sizeMax;i++) { eVectorsPrev[i] = (double*)malloc(sizeMax*sizeof(double)); printf("eVectorsPrev %d-th element allocated. %d allocated\n",i,(sizeMax*sizeof(double))); } Log: nDim = 2485 sizeMax = 70 End hamilt alloc. 19880 allocated End transProb alloc. 39200 allocated eValues allocated. 560 allocated eVectors allocated. 280 allocated So it crashes at the start of the loop of allocation. If i delete this loop it crashes at the next line of allocation. Does it mean that with the numbers like this i have not enough memory?? Thank you.

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• Cpp some basic problems

  - by DevAno1

  Hello. My task was as follows : Create class Person with char*name and int age. Implement contructor using dynamic allocation of memory for variables, destructor, function init and friend function show. Then transform this class to header and cpp file and implement in other program. Ok so I've almost finished my Person class, but I get error after destructor. First question is how to write this properly ? #include <iostream> using namespace std; class Person { char* name; int age; public: int * take_age(); Person(){ int size=0; cout << "Give length of char*" << endl; cin >> size; name = new char[size]; age = 0; } ~Person(){ cout << "Destroying resources" << endl; delete *[] name; delete * take_age(); } friend void(Person &p); int * Person::take_age(){ return age; } void init(char* n, int a) { name = n; age = a; } void show(Person &p){ cout << "Name: " << p.name << "," << "age: " << p.age << endl; } }; int main(void) { Person *p = new Person; p->init("Mary", 25); p.show(); system("PAUSE"); return 0; } And now with header/implementation part : - do I need to introduce constructor in header/implementation files ? If yes - how? - my show() function is a friendly function. Should I take it into account somehow ? I already failed to return this task on my exam, but still I'd like to know how to implement it.

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• Slackware Linux: Glib can't find libffi.so.6. Where is it trying to look?

  - by Mathmagician

  I have libffi installed and it's in /usr/local/lib, yet the glib make process can't find it /home/mathmagi/src/glib-2.32.4/gio/.libs/lt-glib-compile-resources: error while loading shared libraries: libffi.so.6: cannot open shared object file: No such file or directory /home/mathmagi/src/glib-2.32.4/gio/.libs/lt-glib-compile-resources: error while loading shared libraries: libffi.so.6: cannot open shared object file: No such file or directory /home/mathmagi/src/glib-2.32.4/gio/.libs/lt-glib-compile-resources: error while loading shared libraries: libffi.so.6: cannot open shared object file: No such file or directory /home/mathmagi/src/glib-2.32.4/gio/.libs/lt-glib-compile-resources: error while loading shared libraries: libffi.so.6: cannot open shared object file: No such file or directory make[4]: Entering directory `/home/mathmagi/src/glib-2.32.4/gio/tests' GEN gdbus-test-codegen-generated.c GEN test_resources.c /home/mathmagi/src/glib-2.32.4/gio/.libs/lt-glib-compile-resources: error while loading shared libraries: libffi.so.6: cannot open shared object file: No such file or directory make[4]: *** [test_resources.c] Error 127 make[4]: Leaving directory `/home/mathmagi/src/glib-2.32.4/gio/tests' make[3]: *** [all-recursive] Error 1 make[3]: Leaving directory `/home/mathmagi/src/glib-2.32.4/gio' make[2]: *** [all] Error 2 make[2]: Leaving directory `/home/mathmagi/src/glib-2.32.4/gio' make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory `/home/mathmagi/src/glib-2.32.4' make: *** [all] Error 2 It's definitely in /usr/local/lib! bash-4.1# updatedb bash-4.1# locate libffi.so.6 /usr/local/lib/libffi.so.6 /usr/local/lib/libffi.so.6.0.0 /home/mathmagi/src/libffi-3.0.11/x86_64-unknown-linux-gnu/.libs/libffi.so.6 /home/mathmagi/src/libffi-3.0.11/x86_64-unknown-linux-gnu/.libs/libffi.so.6.0.0 With glib I've tried LDFLAGS=-L/usr/local/lib ./configure Doesn't work. How do I find where glib is looking and change it?

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• Why do I start at privilege level 1 when logging into a Cisco ASA 5510?

  - by Alain O'Dea

  I have created a test user that is set to privilege 15 in the config: username test password **************** encrypted privilege 15 When I log in to the ASA 5510 I am in privilege 1 according to sh curpriv: login as: test [email protected]'s password: Type help or '?' for a list of available commands. asa> sh curpriv Username : test Current privilege level : 1 Current Mode/s : P_UNPR Attempting enable fails even though I know I have the correct enable password: asa> en Password: ************************* Password: ************************* Password: ************************* Access denied. Logging in from unprivileged puts me on privilege 15 and I can do as a please: asa> login Username : test Pasword: ************************* asa> sh curpriv Current privilege level : 15 Current Mode/s : P_PRIV asa> The only thing I can track this to is a configuration change I made where I removed a VPN user we no longer needed. Why do I start at privilege level 1 when logging into a Cisco ASA 5510?

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• How do I easily repair a single unreadable block on a Linux disk?

  - by Nelson

  My Linux system has started throwing SMART errors in the syslog. I tracked it down and believe the problem is a single block on the disk. How do I go about easily getting the disk to reallocate that one block? I'd like to know what file got destroyed in the process. (I'm aware that if one block fails on a disk others are likely to follow; I have a good ongoing backup and just want to try to keep this disk working.) Searching the web leads to the Bad block HOWTO, which describes a manual process on an unmounted disk. It seems complicated and error-prone. Is there a tool to automate this process in Linux? My only other option is the manufacturer's diagnostic tool, but I presume that'll clobber the bad block without any reporting on what got destroyed. Worst case, it might be filesystem metadata. The disk in question is the primary system partition. Using ext3fs and LVM. Here's the error log from syslog and the relevant bit from smartctl. smartd[5226]: Device: /dev/hda, 1 Currently unreadable (pending) sectors Error 1 occurred at disk power-on lifetime: 17449 hours (727 days + 1 hours) ... Error: UNC at LBA = 0x00d39eee = 13868782 There's a full smartctl dump on pastebin.

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• Installing VirtualBox on BackTrack 5

  - by m0skit0

  I'm getting this error when running VirtualBox's installation script: $ sudo ~/Downloads/VirtualBox-4.1.14-77440-Linux_x86.run Verifying archive integrity... All good. Uncompressing VirtualBox for Linux installation........... VirtualBox Version 4.1.14 r77440 (2012-04-12T16:20:44Z) installer Removing previous installation of VirtualBox 4.1.14 r77440 from /opt/VirtualBox Installing VirtualBox to /opt/VirtualBox tar: Record size = 8 blocks Python found: python, installing bindings... Building the VirtualBox kernel modules Error! Bad return status for module build on kernel: 3.2.6 (i686) Consult the make.log in the build directory /var/lib/dkms/vboxhost/4.1.14/build/ for more information. ERROR: binary package for vboxhost: 4.1.14 not found Here's the log: $ cat /var/lib/dkms/vboxhost/4.1.14/build/make.log DKMS make.log for vboxhost-4.1.14 for kernel 3.2.6 (i686) Sun May 13 14:32:52 CEST 2012 make: Entering directory `/usr/src/linux-headers-3.2.6' /usr/src/linux-headers-3.2.6/arch/x86/Makefile:39: /usr/src/linux-headers-3.2.6/arch/x86/Makefile_32.cpu: No such file or directory make: *** No rule to make target `/usr/src/linux-headers-3.2.6/arch/x86/Makefile_32.cpu'. Stop. make: Leaving directory `/usr/src/linux-headers-3.2.6' /usr/src/linux-headers-3.2.6/arch/x86/ directory: $ ls /usr/src/linux-headers-3.2.6/arch/x86/ Kconfig Makefile ia32 lguest mm pci tools video Kconfig.cpu boot kernel lib net platform um xen Kconfig.debug crypto kvm math-emu oprofile power vdso Makefile references on "cpu" $ cat /usr/src/linux-headers-3.2.6/arch/x86/Makefile | grep cpu include $(srctree)/arch/x86/Makefile_32.cpu # FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu) Before upgrading to 3.X I didn't have this problem, the script would install VB correctly. Any ideas on what might be causing this? Thanks in advance!

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• How do I make Linux recognize a new SATA /dev/sda drive I hot swapped in without rebooting?

  - by Philip Durbin

  Hot swapping out a failed SATA /dev/sda drive worked fine, but when I went to swap in a new drive, it wasn't recognized: [root@fs-2 ~]# tail -18 /var/log/messages May 5 16:54:35 fs-2 kernel: ata1: exception Emask 0x10 SAct 0x0 SErr 0x50000 action 0xe frozen May 5 16:54:35 fs-2 kernel: ata1: SError: { PHYRdyChg CommWake } May 5 16:54:40 fs-2 kernel: ata1: link is slow to respond, please be patient (ready=0) May 5 16:54:45 fs-2 kernel: ata1: device not ready (errno=-16), forcing hardreset May 5 16:54:45 fs-2 kernel: ata1: soft resetting link May 5 16:54:50 fs-2 kernel: ata1: link is slow to respond, please be patient (ready=0) May 5 16:54:55 fs-2 kernel: ata1: SRST failed (errno=-16) May 5 16:54:55 fs-2 kernel: ata1: soft resetting link May 5 16:55:00 fs-2 kernel: ata1: link is slow to respond, please be patient (ready=0) May 5 16:55:05 fs-2 kernel: ata1: SRST failed (errno=-16) May 5 16:55:05 fs-2 kernel: ata1: soft resetting link May 5 16:55:10 fs-2 kernel: ata1: link is slow to respond, please be patient (ready=0) May 5 16:55:40 fs-2 kernel: ata1: SRST failed (errno=-16) May 5 16:55:40 fs-2 kernel: ata1: limiting SATA link speed to 1.5 Gbps May 5 16:55:40 fs-2 kernel: ata1: soft resetting link May 5 16:55:45 fs-2 kernel: ata1: SRST failed (errno=-16) May 5 16:55:45 fs-2 kernel: ata1: reset failed, giving up May 5 16:55:45 fs-2 kernel: ata1: EH complete I tried a couple things to make the server find the new /dev/sda, such as rescan-scsi-bus.sh but they didn't work: [root@fs-2 ~]# echo "---" > /sys/class/scsi_host/host0/scan -bash: echo: write error: Invalid argument [root@fs-2 ~]# [root@fs-2 ~]# /root/rescan-scsi-bus.sh -l [snip] 0 new device(s) found. 0 device(s) removed. [root@fs-2 ~]# [root@fs-2 ~]# ls /dev/sda ls: /dev/sda: No such file or directory I ended up rebooting the server. /dev/sda was recognized, I fixed the software RAID, and everything is fine now. But for next time, how can I make Linux recognize a new SATA drive I have hot swapped in without rebooting? The operating system in question is RHEL5.3: [root@fs-2 ~]# cat /etc/redhat-release Red Hat Enterprise Linux Server release 5.3 (Tikanga) The hard drive is a Seagate Barracuda ES.2 SATA 3.0-Gb/s 500-GB, model ST3500320NS. Here is the lscpi output: [root@fs-2 ~]# lspci 00:00.0 RAM memory: nVidia Corporation MCP55 Memory Controller (rev a2) 00:01.0 ISA bridge: nVidia Corporation MCP55 LPC Bridge (rev a3) 00:01.1 SMBus: nVidia Corporation MCP55 SMBus (rev a3) 00:02.0 USB Controller: nVidia Corporation MCP55 USB Controller (rev a1) 00:02.1 USB Controller: nVidia Corporation MCP55 USB Controller (rev a2) 00:04.0 IDE interface: nVidia Corporation MCP55 IDE (rev a1) 00:05.0 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:05.1 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:05.2 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:06.0 PCI bridge: nVidia Corporation MCP55 PCI bridge (rev a2) 00:08.0 Bridge: nVidia Corporation MCP55 Ethernet (rev a3) 00:09.0 Bridge: nVidia Corporation MCP55 Ethernet (rev a3) 00:0a.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0b.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0c.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0d.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0e.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0f.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration 00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map 00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller 00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control 00:19.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration 00:19.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map 00:19.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller 00:19.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control 03:00.0 VGA compatible controller: Matrox Graphics, Inc. MGA G200e [Pilot] ServerEngines (SEP1) (rev 02) 04:00.0 PCI bridge: NEC Corporation uPD720400 PCI Express - PCI/PCI-X Bridge (rev 06) 04:00.1 PCI bridge: NEC Corporation uPD720400 PCI Express - PCI/PCI-X Bridge (rev 06) Update: In perhaps a dozen cases, we've been forced to reboot servers because hot swap hasn't "just worked." Thanks for the answers to look more into the SATA controller. I've included the lspci output for the problematic system above (hostname: fs-2). I could still use some help understanding what exactly isn't supported hardware-wise in terms of hot swap for that system. Please let me know what other output besides lspci might be useful. The good news is that hot swap "just worked" today on one of our servers (hostname: www-1), which is very rare for us. Here is the lspci output: [root@www-1 ~]# lspci 00:00.0 RAM memory: nVidia Corporation MCP55 Memory Controller (rev a2) 00:01.0 ISA bridge: nVidia Corporation MCP55 LPC Bridge (rev a3) 00:01.1 SMBus: nVidia Corporation MCP55 SMBus (rev a3) 00:02.0 USB Controller: nVidia Corporation MCP55 USB Controller (rev a1) 00:02.1 USB Controller: nVidia Corporation MCP55 USB Controller (rev a2) 00:04.0 IDE interface: nVidia Corporation MCP55 IDE (rev a1) 00:05.0 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:05.1 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:05.2 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:06.0 PCI bridge: nVidia Corporation MCP55 PCI bridge (rev a2) 00:08.0 Bridge: nVidia Corporation MCP55 Ethernet (rev a3) 00:09.0 Bridge: nVidia Corporation MCP55 Ethernet (rev a3) 00:0b.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0c.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0f.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:18.0 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] HyperTransport Configuration 00:18.1 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Address Map 00:18.2 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] DRAM Controller 00:18.3 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Miscellaneous Control 00:18.4 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Link Control 00:19.0 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] HyperTransport Configuration 00:19.1 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Address Map 00:19.2 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] DRAM Controller 00:19.3 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Miscellaneous Control 00:19.4 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Link Control 03:00.0 VGA compatible controller: Matrox Graphics, Inc. MGA G200e [Pilot] ServerEngines (SEP1) (rev 02) 04:00.0 PCI bridge: NEC Corporation uPD720400 PCI Express - PCI/PCI-X Bridge (rev 06) 04:00.1 PCI bridge: NEC Corporation uPD720400 PCI Express - PCI/PCI-X Bridge (rev 06) 09:00.0 SCSI storage controller: LSI Logic / Symbios Logic SAS1064ET PCI-Express Fusion-MPT SAS (rev 04)

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• How can a Linux Administrator improve their shell scripting and automation skills?

  - by ewwhite

  In my organization, I work with a group of NOC staff, budding junior engineers and a handful of senior engineers; all with a focus on Linux. One interesting step in the way the company grows talent is that there's a path from the NOC to the senior engineering ranks. Viewing the talent pool as a relative newcomer, I see that there's a split in the skill sets that tends to grow over time... There are engineers who know one or several particular technologies well and are constantly immersed... e.g. MySQL, firewalls, SAN storage, load balancers... There are others who are generalists and can navigate multiple technologies. All learn enough Linux (commands, processes) to do what they need and use on a daily basis. A differentiating factor between some of the staff is how well they embrace scripting, automation and configuration management methodologies. For instance, we have two engineers who do the bulk of Amazon AWS CloudFormation work, and another who handles most of the Puppet infrastructure. Perhaps a quarter of the engineers are adept at BASH shell scripting. Looking at this in the context of the incredibly high demand for DevOps skills in the job market, I'm curious how other organizations foster the development of these skills and grow their internal talent. Scripting doesn't seem like a particularly-teachable concept. How does a sysadmin improve their shell scripting? Is there still a place for engineers who do not/cannot keep up in the DevOps paradigm? Are we simply to assume that some people will be left behind as these technologies evolve? Is that okay?

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• How to mount vfat drive on Linux with ownership other than root?

  - by Norman Ramsey

  I'm running into trouble mounting an iPod on a newly upgraded Debian Squeeze. I suspect either a protocol has changed or I've tickled a bug, which I don't know where to report. I'm trying to mount the iPod so that I have permission to read and write it. But my efforts come to nothing: $ sudo mount -v -t vfat -o uid=32074,gid=6202 /dev/sde2 /mnt /dev/sde2 on /mnt type vfat (rw,uid=32074,gid=6202) $ ls -l /mnt total 80 drwxr-xr-x 2 root root 16384 Jan 1 2000 Calendars drwxr-xr-x 2 root root 16384 Jan 1 2000 Contacts drwxr-xr-x 2 root root 16384 Jan 1 2000 Notes drwxr-xr-x 3 root root 16384 Jun 23 2007 Photos drwxr-xr-x 6 root root 16384 Jun 19 2007 iPod_Control $ sudo umount /mnt $ sudo mount -v -t vfat -o uid=nr,gid=nr /dev/sde2 /mnt /dev/sde2 on /mnt type vfat (rw,uid=32074,gid=6202) $ ls -l /mnt total 80 drwxr-xr-x 2 root root 16384 Jan 1 2000 Calendars drwxr-xr-x 2 root root 16384 Jan 1 2000 Contacts drwxr-xr-x 2 root root 16384 Jan 1 2000 Notes drwxr-xr-x 3 root root 16384 Jun 23 2007 Photos drwxr-xr-x 6 root root 16384 Jun 19 2007 iPod_Control As you see, I've tried both symbolic and numberic IDs, but the files persist in being owned by root (and only writable by root). The IDs are really mine; I've had the UID since 1993. $ id uid=32074(nr) gid=6202(nr) groups=6202(nr),0(root),2(bin),4(adm),... I've put an strace at http://pastebin.com/Xue2u9FZ, and the mount(2) call looks good: mount("/dev/sde2", "/mnt", "vfat", MS_MGC_VAL, "uid=32074,gid=6202") = 0 Finally, here's my kernel version from uname -a: Linux homedog 2.6.32-5-686 #1 SMP Mon Jun 13 04:13:06 UTC 2011 i686 GNU/Linux Does anyone know if I should be doing something different, or If there is a workaround, or If this is a bug, where it should be reported?

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• how to cause linux system datetime to run faster than real world datetime?

  - by JamesThomasMoon1979

  Background I want to monitor a running linux system over several days. It's a custom gentoo build and with much custom software on board. This software has ongoing maintenance timers and cron scripts and other clock driven events. I need to verify these scheduled events are working. Problem Waiting for the system to step through daily and weekly activity is a long wait time. And modifying all clock-based timers on the system would be time consuming. Yet, I often want to test a system's end-to-end scheduled activities without waiting a week. Potential Solution Have the linux system under test appear to run through it's daily cycle of activity within just a few hours. My Question for Serverfault Is there a way to cause the system's time to run faster than real world time? My first thought is manipulating the ntp daemon to repeatedly and smoothly increment the clock . Any other ideas? And yes, I know this may have strange side affects. However, the system has no important or time critical interactions with systems outside of itself. And this may be a valuable testing technique.

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• stat command filesize reporting on busybox

  - by datadevil

  I'm trying to write a shell script in busybox to check the filesize of a file. Having read that stat is more reliable then ls, I decided to use that, but somehow when using the following command: stat -c %s filename I get the following output: 559795. This goes for the following 2 files (shown using ls -la): 0 Jan 20 16:32 foo_empty 4 Jan 20 16:32 foo_not_empty Anyone know what's happening there? I can just go back to using ls, but I'm not understanding what's happening here, and that's bothering me..

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• How to create VHD disk image from a Linux live system?

  - by Federico

  Once more, I have to resort at the experts here at SuperUser, as my other sources (mainly Google ;-)) didn't prove very helpful... So basically, I would like to create a VHD image of a physical disk to be archived/accessed/maybe even mounted in a virtual machine. Now, there are dozens of articles and tutorials on how to do that on the web, but none that meets exactly the conditions I would like to achieve: I would like the destination file to be a VHD image, as Windows 7 can mount it natively, even over the network and many other programs can use it (VirtualBox, ...) The disk I'm trying to image contains a Windows XP install, so in theory, I could use the disk2vhd utility, but I would like to find a solution that doesn't require booting that Windows XP install (ie keep the disk read-only) Thus I was searching for a solution involving some sort of live system (running from a USB stic or the network) However, all the solutions that I've came across either make use of disk2vhd or use the dd command under linux, which does a complete copy of the disk (ie even empty blocks) and does not output a VHD file. Is there a tool/program under Linux that can directly create a VHD file? Or is is possible to convert a raw disk image created using dd to a VHD file, without allocating space for the empty blocks? How would you proceed? As always, any advice or comment is highly appreciated!!

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• QNAP NAS 509 (LINUX) - how to unmout busy volume and find physical disk?

  - by Horst Walter

  On my NAS QNAP TS 509 I do have a technical issue. I need to run e2fsck. This works fine for me on md0 (see below), but how can I unmount the busy devices md9 and sda4 in order to do the same. Whenever I try, I fail because the device is busy. [This part is solved, see below] In order to further track down the issue, I'd need to sort out the physical disk to device relationship. How can I find out this, e.g. md0 is a stripped volume on 2 disk (but I need to find out on what physical disk). Remark: As you can easily derive from my questions, I am not a Linux expert, but manage to get along. /dev/ram0 124.0M 94.1M 29.8M 76% / tmpfs 32.0M 80.0k 31.9M 0% /tmp /dev/sda4 310.0M 103.9M 206.1M 34% /mnt/ext /dev/md9 509.5M 39.2M 470.2M 8% /mnt/HDA_ROOT /dev/md0 1.8T 1.4T 444.7G 76% /share/MD0_DATA tmpfs 32.0M 0 32.0M 0% /.eaccelerator.tmp -- Added -- QNAP seems to be based on Busybox. I do not find something like init / telinit / runlevel. At busybox docs it says that I need to run the below. But in /var/service sv is not available. I want to go to single user mode to unmount the devices. # cd /var/service # sv d * # sv u getty* -- Added, thanks A4L -- This QNAP Box runs a special flavor of Linux, so not all SOPs do apply. In my particular case I found a services.sh script, stopping all services. After that the drive could be unmounted. The information passed by A4L is valid and worth reading it, maybe I'll profit from it next time. Links: http://unix.stackexchange.com/questions/19918/umount-device-is-busy and http://unix.stackexchange.com/questions/15024/umount-device-is-busy-why So the unmount issue is solved, still looking for the best option to find the physical to volume mapping.

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• How do I make Linux recognize a new SATA /dev/sda drive I hot swapped in without rebooting?

  - by Philip Durbin

  Hot swapping out a failed SATA /dev/sda drive worked fine, but when I went to swap in a new drive, it wasn't recognized: [root@fs-2 ~]# tail -18 /var/log/messages May 5 16:54:35 fs-2 kernel: ata1: exception Emask 0x10 SAct 0x0 SErr 0x50000 action 0xe frozen May 5 16:54:35 fs-2 kernel: ata1: SError: { PHYRdyChg CommWake } May 5 16:54:40 fs-2 kernel: ata1: link is slow to respond, please be patient (ready=0) May 5 16:54:45 fs-2 kernel: ata1: device not ready (errno=-16), forcing hardreset May 5 16:54:45 fs-2 kernel: ata1: soft resetting link May 5 16:54:50 fs-2 kernel: ata1: link is slow to respond, please be patient (ready=0) May 5 16:54:55 fs-2 kernel: ata1: SRST failed (errno=-16) May 5 16:54:55 fs-2 kernel: ata1: soft resetting link May 5 16:55:00 fs-2 kernel: ata1: link is slow to respond, please be patient (ready=0) May 5 16:55:05 fs-2 kernel: ata1: SRST failed (errno=-16) May 5 16:55:05 fs-2 kernel: ata1: soft resetting link May 5 16:55:10 fs-2 kernel: ata1: link is slow to respond, please be patient (ready=0) May 5 16:55:40 fs-2 kernel: ata1: SRST failed (errno=-16) May 5 16:55:40 fs-2 kernel: ata1: limiting SATA link speed to 1.5 Gbps May 5 16:55:40 fs-2 kernel: ata1: soft resetting link May 5 16:55:45 fs-2 kernel: ata1: SRST failed (errno=-16) May 5 16:55:45 fs-2 kernel: ata1: reset failed, giving up May 5 16:55:45 fs-2 kernel: ata1: EH complete I tried a couple things to make the server find the new /dev/sda, such as rescan-scsi-bus.sh but they didn't work: [root@fs-2 ~]# echo "---" > /sys/class/scsi_host/host0/scan -bash: echo: write error: Invalid argument [root@fs-2 ~]# [root@fs-2 ~]# /root/rescan-scsi-bus.sh -l [snip] 0 new device(s) found. 0 device(s) removed. [root@fs-2 ~]# [root@fs-2 ~]# ls /dev/sda ls: /dev/sda: No such file or directory I ended up rebooting the server. /dev/sda was recognized, I fixed the software RAID, and everything is fine now. But for next time, how can I make Linux recognize a new SATA drive I have hot swapped in without rebooting? The operating system in question is RHEL5.3: [root@fs-2 ~]# cat /etc/redhat-release Red Hat Enterprise Linux Server release 5.3 (Tikanga) The hard drive is a Seagate Barracuda ES.2 SATA 3.0-Gb/s 500-GB, model ST3500320NS. Here is the lscpi output: [root@fs-2 ~]# lspci 00:00.0 RAM memory: nVidia Corporation MCP55 Memory Controller (rev a2) 00:01.0 ISA bridge: nVidia Corporation MCP55 LPC Bridge (rev a3) 00:01.1 SMBus: nVidia Corporation MCP55 SMBus (rev a3) 00:02.0 USB Controller: nVidia Corporation MCP55 USB Controller (rev a1) 00:02.1 USB Controller: nVidia Corporation MCP55 USB Controller (rev a2) 00:04.0 IDE interface: nVidia Corporation MCP55 IDE (rev a1) 00:05.0 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:05.1 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:05.2 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:06.0 PCI bridge: nVidia Corporation MCP55 PCI bridge (rev a2) 00:08.0 Bridge: nVidia Corporation MCP55 Ethernet (rev a3) 00:09.0 Bridge: nVidia Corporation MCP55 Ethernet (rev a3) 00:0a.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0b.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0c.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0d.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0e.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0f.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration 00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map 00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller 00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control 00:19.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration 00:19.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map 00:19.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller 00:19.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control 03:00.0 VGA compatible controller: Matrox Graphics, Inc. MGA G200e [Pilot] ServerEngines (SEP1) (rev 02) 04:00.0 PCI bridge: NEC Corporation uPD720400 PCI Express - PCI/PCI-X Bridge (rev 06) 04:00.1 PCI bridge: NEC Corporation uPD720400 PCI Express - PCI/PCI-X Bridge (rev 06) Update: In perhaps a dozen cases, we've been forced to reboot servers because hot swap hasn't "just worked." Thanks for the answers to look more into the SATA controller. I've included the lspci output for the problematic system above (hostname: fs-2). I could still use some help understanding what exactly isn't supported hardware-wise in terms of hot swap for that system. Please let me know what other output besides lspci might be useful. The good news is that hot swap "just worked" today on one of our servers (hostname: www-1), which is very rare for us. Here is the lspci output: [root@www-1 ~]# lspci 00:00.0 RAM memory: nVidia Corporation MCP55 Memory Controller (rev a2) 00:01.0 ISA bridge: nVidia Corporation MCP55 LPC Bridge (rev a3) 00:01.1 SMBus: nVidia Corporation MCP55 SMBus (rev a3) 00:02.0 USB Controller: nVidia Corporation MCP55 USB Controller (rev a1) 00:02.1 USB Controller: nVidia Corporation MCP55 USB Controller (rev a2) 00:04.0 IDE interface: nVidia Corporation MCP55 IDE (rev a1) 00:05.0 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:05.1 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:05.2 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3) 00:06.0 PCI bridge: nVidia Corporation MCP55 PCI bridge (rev a2) 00:08.0 Bridge: nVidia Corporation MCP55 Ethernet (rev a3) 00:09.0 Bridge: nVidia Corporation MCP55 Ethernet (rev a3) 00:0b.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0c.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:0f.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3) 00:18.0 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] HyperTransport Configuration 00:18.1 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Address Map 00:18.2 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] DRAM Controller 00:18.3 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Miscellaneous Control 00:18.4 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Link Control 00:19.0 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] HyperTransport Configuration 00:19.1 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Address Map 00:19.2 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] DRAM Controller 00:19.3 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Miscellaneous Control 00:19.4 Host bridge: Advanced Micro Devices [AMD] K10 [Opteron, Athlon64, Sempron] Link Control 03:00.0 VGA compatible controller: Matrox Graphics, Inc. MGA G200e [Pilot] ServerEngines (SEP1) (rev 02) 04:00.0 PCI bridge: NEC Corporation uPD720400 PCI Express - PCI/PCI-X Bridge (rev 06) 04:00.1 PCI bridge: NEC Corporation uPD720400 PCI Express - PCI/PCI-X Bridge (rev 06) 09:00.0 SCSI storage controller: LSI Logic / Symbios Logic SAS1064ET PCI-Express Fusion-MPT SAS (rev 04)

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• How can I permanently fix my date synchronize problem in linux?

  - by gr33d

  Ubuntu 7.10 server i386 clock/date/time won't stay in sync. Are their log files I can view to tell when the clock changes? For a temporary fix, I created a file in /etc/cron.hourly: #!/bin/sh ntpdate time.nist.gov However, this still leaves a potential hour of unchecked time. Is there a cron.minutely? That would still leave a potential minute of unchecked time. I have read about CMOS battery problems, but what if this does not fix it? I'd like to be able to troubleshoot this as a completely software problem. My squid logs are showing dates back in 2005 when the clock changes, and my time-sensitive access controls are skewed and end up allowing users to surf prohibited websites during business hours.

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• Installing Java 1.5 on Ubuntu?

  - by StackedCrooked

  I already have Java 1.6, but I need to test something with 1.5. I have downloaded the .bin file from http://java.sun.com/javase/downloads/index_jdk5.jsp using the Sun Download Manager. Now I want to create a deb file from this bin file: $ fakeroot make-jpkg java_ee_sdk-5_01-linux.bin Creating temporary directory: /tmp/make-jpkg.Zpm1Y7LbZ0 Loading plugins: blackdown-j2re.sh blackdown-j2sdk.sh common.sh ibm-j2re.sh ibm-j2sdk.sh j2re.sh j2sdk-doc.sh j2sdk.sh j2se.sh sun-j2re.sh sun-j2sdk-doc.sh sun-j2sdk.sh Detected Debian build architecture: i386 Detected Debian GNU type: i486-linux-gnu No matching plugin was found. Removing temporary directory: done How can I fix the "No matching plugin was found." error?

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• /dev/input/uinput Device appears to be 'broken'

  - by Adam Luchjenbroers

  I'm trying to setup Pystromo so that I can remap the keys on my Belkin N52TE gamepad. Pystromo basically captures the key strokes and then outputs the remapped keystrokes to the uinput device. However, at the moment it simply swallows the input and outputs absolutely nothing. I've tracked the issue to something being wrong with my uinput device, with the smoking gun being: # ls -l /dev/input/uinput crw-rw---- 1 root plugdev 10, 223 Dec 31 2009 /dev/input/uinput # cat /dev/input/uinput cat: /dev/input/uinput: No such device The uinput module is loaded, and can be clearly seen via lsmod. Anyone seen this before, or can think of something worth attempting? Current Setup Gentoo Linux Kernel 2.6.32 (Gentoo Sources 2.6.32-r1) HP DV7 Laptop Output dmesg dmesg | grep uinput does nothing, and no new lines appear if I run modprobe -r uinput && modprobe uinput. Yet the uinput module can clearly be seen when running lsmod: # lsmod | grep uinput uinput 6200 0 lsusb # lsusb Bus 005 Device 003: ID 050d:0200 Belkin Components Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 002: ID 1532:0101 Razer USA, Ltd Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 002: ID 5986:0143 Acer, Inc Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 007 Device 002: ID 03f0:171d Hewlett-Packard Wireless (Bluetooth + WLAN) Interface [Integrated Module] Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub lsusb -v PasteBin Update Hmm, updating evdev and hal seems to have partially fixed it. /dev/input/uinput still can't be accessed but Pystromo is now remapping keys successfully. I'm a little bit mystified about what's going on here, but it seems that my understanding of how all this works is flawed. Since I've posted a bounty, I'll leave this here for someone to post an explanation for how user-space input devices work under the hood.

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• Comments in a multi-line bash command

  - by Nicolas Raoul

  This single-command BASH script file is difficult to understand, so I want to write a comment for each of the actions: grep -R "%" values* \ | sed -e "s/%/\n%/" \ | grep "%" \ | grep -v " % " \ | grep -v " %<" \ | grep -v "%s" \ | grep -v "%d" \ | grep -v "%1$s" I would hate having to duplicate lines, or having each comment far away from the line it applies to. But at the same time BASH does not seem to allow "in-line" comments. Any elegant way to solve this problem?

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• how i can identify which process is making UDP traffic on linux?

  - by boos

  my machine is continously making udp dns traffic request. what i need to know is the PID of the process generating this traffic. The normal way in TCP connection is to use netstat/lsof and get the process associated at the pid. Is UDP the connection is stateles, so, when i call netastat/lsof i can see it only if the UDP socket is opened and it's sending traffic. I have tried with lsof -i UDP and with nestat -anpue but i cant be able to find wich process is doing that request because i need to call lsof/netstat exactly when the udp traffic is sended, if i call lsof/netstat before/after the udp datagram is sended is impossible to view the opened UDP socket. call netstat/lsof exactly when 3/4 udp packet is sended is IMPOSSIBLE. how i can identify the infamous process ? I have already inspected the traffic to try to identify the sended PID from the content of the packet, but is not possible to identify it from the contect of the traffic. anyone can help me ? I'm root on this machine FEDORA 12 Linux noise.company.lan 2.6.32.16-141.fc12.x86_64 #1 SMP Wed Jul 7 04:49:59 UTC 2010 x86_64 x86_64 x86_64 GNU/Linux

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• How to disconnect a running bash job from the shell in Linux?

  - by raven

  I have a script that starts a server on a remote VM. All works great until I close the shell where I executed the script. When the shell closes, so does the server. After some looking around I found the following: & will send the job to the background when executed with the symbol disown -h will disconnect the job from the shell and allow it to run regardless of the shell. The command I used is: ./startServer.sh nasb_wxscat160_catalog-4.1.6 1.0.8 > catalog-log.txt & disown -h When I closed the shell and checked using ps -ef | grep java to see if the job is still working I did see it in the list. However when I tried to connect to the server it was unresponsive. On deeper inspection, the log file was filled just until I closed the shell and using the ps -m flag I say the process jobs were not working. Has any one encountered some thing of this sort?

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• How do I load balance between two Linux machines?

  - by William Hilsum

  Inspired by the Stack Overflow network, I am now obsessed with HAProxy and trying to use it myself. At the moment, each HAProxy box has got two network cards (well, two configured, I can have a maximum of 4 and wasn't sure if they needed their own one for management between the boxes). On both machines, the backend one (eth1) is a private IP that goes to a switch connected to the webservers, and the front facing one (eth0) has a public internet IP that is routed straight though. In addition, I have created an additional virtual ip for eth0 called eth0:0 which has got a third public ip address. I just about get how to use it for load balancing between multiple web servers that are behind it, but, I am failing to load balance between the two HAProxy boxes - they appear to fight for the virtual IP, but, this does not appear to be a smart solution. Now, by using the virtual shared IP address, this solution appears to work and does seem to give me maximum uptime, but, is this the correct way to do it, or is there a smarter way? I have been looking at other Linux packages such as keepalived, but, I have only been using Linux (server) for a week now and am at the limits of my understanding. Is there anyone who has done this before and can you advise anything for maximum uptime?

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• How can I format an SD card with a more robust Linux-usable filesystem with a specific cluster size for better write performace?

  - by Harvey

  Goal: microSD card formatted... for best write performance for use only with embedded Linux for better reliability (random power failures may occur) using an 64kB cluster size I'm using an 8GB microSD card for data storage inside an embedded Linux/ARM device. The SD card is not removable. I've been using ext3 instead of the pre-installed FAT32 because it seems to better handle random power failures during writes. However, I kept noticing that my write performance is always best with the pre-installed FAT32 from Kingston. If I reformat the card with FAT32, the performance still suffers. After browsing wikipedia, I stumbled upon the following comment saying that some cards are optimized for specific cluster sizes. In my case, the Kingston comes pre-formatted for an 64kB cluster size. Risks of reformatting Reformatting an SD card with a different file system, or even with the same one, may make the card slower, or shorten its lifespan. Some cards use wear leveling, in which frequently modified blocks are mapped to different portions of memory at different times, and some wear-leveling algorithms are designed for the access patterns typical of the file allocation table on a FAT16 or FAT32 device.[60] In addition, the preformatted file system may use a cluster size that matches the erase region of the physical memory on the card; reformatting may change the cluster size and make writes less efficient.

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• How do I change the Dropbox directory on a headless GNU/Linux server?

  - by DrTwox

  I have installed Dropbox 2.0.0 via command line on my home server (Ubuntu Server 12.04) to use for off-site automated backups, but I can't change the directory that the Dropbox daemon keeps synced. I've tried the following: The official docs say to use the desktop application, which is not applicable in my situation. However I installed the desktop app on my desktop machine and changed the default folder location, but I can't find where this change is stored in the ~/.dropbox/ directory so I can make the same change on the server. This page (and several others) recommends a Python script to do the job. Looking at the script, it opens a SQLite database called ~/.dropbox/dropbox.db, which does not exist on my Dropbox install, leading me to believe the script is out-of-date. This forum thread suggests manually inserting the required row in the config.db database, which I did, but it made no difference. I checked the same database file on my desktop machine, and it does not have the dropbox_path key, so I'm presuming the information in that thread is also out of date for version 2.0. I have tried to launch the Dropbox GUI configuration wizard over SSH with X11 forwarding, as suggested in one of the answers, but the binary must detect the absence of a local X11 install and it starts a command line daemon instead, which provides no means to change the option I need. I am currently using a symlink, as suggested as an answer, but this is a kludge. I would like to know the correct way to make the change. How do I change the Dropbox directory on a headless GNU/Linux server? Update: I've ditched Dropbox and started using Copy. Their Linux tools and support is far superior to Dropbox. I leave this question here in case someone, someday, can answer it.

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