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  • Cannot run a VM with more than three network interfaces with KVM

    - by Bostonvaulter
    I'm running KVM on top of Ubuntu 10.10 Server I can create VM's (Virtual Machine) and network interfaces fine but I cannot seem to add more than three network interfaces. As soon as I have a VM with four network interfaces it gets stuck on startup at the starting SeaBIOS page with this message: Starting SeaBIOS (version pre-0.6.1-20100702_143500-palmer) So far I've verified this with two VM's, a Ubuntu 10.10 desktop and a Vyatta router. The specific network hardware I assign to the VM's doesn't seem to matter. I'm trying to have one bridged interface and three private networks using Vyatta to route between them. Does anyone know why I can't run a VM with more than three network interfaces? Edit: Additionally the KVM thread responsible for the specific VM hangs using ~100% CPU (i.e. one core). Here's the command for the process that is hanging: /usr/bin/kvm -S -M pc-0.12 -enable-kvm -m 512 -smp 1,sockets=1,cores=1,threads=1 -name vyatta -uuid 6dff7c94-6810-423e-5fea-fec10da0e9b7 -nodefaults -chardev socket,id=monitor,path=/var/lib/libvirt/qemu/vyatta.monitor,server,nowait -mon chardev=monitor,mode=readline -rtc base=utc -boot c -drive file=/home/rams/virtual-machines/vyatta.img,if=none,id=drive-ide0-0-0,boot=on,format=raw -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -drive if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw -device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -device rtl8139,vlan=0,id=net0,mac=00:54:00:be:cc:4b,bus=pci.0,addr=0x3 -net tap,fd=97,vlan=0,name=hostnet0 -device rtl8139,vlan=1,id=net1,mac=52:54:00:da:59:ed,bus=pci.0,addr=0x5 -net tap,fd=98,vlan=1,name=hostnet1 -device rtl8139,vlan=2,id=net2,mac=52:54:00:ce:22:b6,bus=pci.0,addr=0x6 -net tap,fd=99,vlan=2,name=hostnet2 -device rtl8139,vlan=3,id=net3,mac=52:54:00:1e:bc:46,bus=pci.0,addr=0x7 -net tap,fd=101,vlan=3,name=hostnet3 -chardev pty,id=serial0 -device isa-serial,chardev=serial0 -usb -vnc 127.0.0.1:0 -k en-us -vga cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 Edit: I've also found an error in dmesg that might be related (it also shows up when running virtd in verbose mode): 14:47:24.399: warning : qemudParsePCIDeviceStrs:1422 : Unexpected exit status '1', qemu probably failed I've also tried disabling app armor but that doesn't seem to make a difference.

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  • libvirt qemu/kvm migration problem

    - by Panda
    I am using kvm and libvirt on my Dell server. Now i am trying to migrate one virtual machine from a physical server to another. However, I failed everytime. In virsh on physicalServer1, I typed: virsh # migrate virtualmachine1 qemu+ssh://username@physicalServer2/system error: operation failed: migration to 'tcp:physicalServer2:49163' failed: migration failed Then I searched FAQ part on libvirt.org. It says: error: operation failed: migration to '...' failed: migration failed This is an error often encountered when trying to migrate with QEMU/KVM. This typically happens with plain migration, when the source VM cannot connect to the destination host. You will want to make sure your hosts are properly configured for migration (see the migration section of this FAQ) I managed to ssh physicalServer2 from a shell on virtualmachine1 so the above red part did not explain my failure. I also open ports on physicalServer2, iptables -L shows following information: Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT udp -- anywhere anywhere udp dpt:domain ACCEPT tcp -- anywhere anywhere tcp dpt:domain ACCEPT udp -- anywhere anywhere udp dpt:bootps ACCEPT tcp -- anywhere anywhere tcp dpt:bootps ACCEPT udp -- anywhere anywhere udp dpt:domain ACCEPT tcp -- anywhere anywhere tcp dpt:domain ACCEPT udp -- anywhere anywhere udp dpt:bootps ACCEPT tcp -- anywhere anywhere tcp dpt:bootps ACCEPT tcp -- anywhere anywhere state NEW tcp dpts:49152:49215 Chain FORWARD (policy ACCEPT) target prot opt source destination ACCEPT all -- anywhere 192.168.122.0/24 state RELATED,ESTABLISHED ACCEPT all -- 192.168.122.0/24 anywhere ACCEPT all -- anywhere anywhere REJECT all -- anywhere anywhere reject-with icmp-port-unreachable REJECT all -- anywhere anywhere reject-with icmp-port-unreachable ACCEPT all -- anywhere 192.168.122.0/24 state RELATED,ESTABLISHED ACCEPT all -- 192.168.122.0/24 anywhere ACCEPT all -- anywhere anywhere REJECT all -- anywhere anywhere reject-with icmp-port-unreachable REJECT all -- anywhere anywhere reject-with icmp-port-unreachable Chain OUTPUT (policy ACCEPT) target prot opt source destination The /var/log/libvirt/qemu/virtualmachine1.log on physicalServer2: 2011-05-06 13:37:30.708: starting up LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/sbin:/sbin:/bin QEMU_AUDIO_DRV=none /usr/bin/kvm -S -M pc-0.14 -enable-kvm -m 2048 -smp 1,sockets=1,cores=1,threads=1 -name openjudge-test -uuid a8c704bc-a4f9-90db-3e57-40e60b00aac1 -nodefconfig -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/virtualmachine1.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=readline -rtc base=utc -boot c -drive file=/media/nfs/virtualmachine1.img,if=none,id=drive-ide0-0-0,format=raw -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -drive if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw -device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -netdev tap,fd=20,id=hostnet0 -device rtl8139,netdev=hostnet0,id=net0,mac=00:16:36:8a:22 :a0,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -usb -vnc 127.0.0.1:2 -vga cirrus -incoming tcp:0.0.0.0:49163 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 char device redirected to /dev/pts/0 2011-05-06 13:37:30.915: shutting down The /var/log/libvirt/qemu/virtualmachine1.log on physicalServer1 is empty. Both physical servers are using Ubuntu 11.04. The libvirt and kvm used are installed by apt-get. The libvirt version is 0.8.8.

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  • SOS, i erased a disk,1T.by mistake

    - by gabriel
    i tried to make bootable a flash drive from the startup disk creator, and i wanted to copy an iso of the 11.10 ubuntu, and when i tried to erase the flash drive i pressed erase on another removable drive 1T storage by mistake, VVVery very very quickly less than one second and with no warning everything was erased i suppose.Is that thing possible?When i tried before theis to erase the flash drive it took around a minute to erase the 8GB.But now less than a second for 1T? Please help, Gabriel

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  • can Dell netbooks with HDTV tuner drive HDMI output to 1920 x 1080 HDTV, and does any other brand of

    - by Jian Lin
    It has been a while that Dell netbook offered an internal HDTV tuner, and it always seem like Dell is the only one that has an internal HDTV tuner? And actually, does anyone have experience with it, since the processor is very basic, can it handle smooth HDTV on screen full size, and especially for the Dell mini 1010, it can output to HDMI, so can it drive an HDTV that is 1920 x 1080? thanks.

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  • How can videos from Ubuntu drive appear on web page and play in an embedded Flash Player?

    - by nLinked
    I have a shared folder on Ubuntu Server 12.04. Users drop videos in. Ubuntu runs a Cron task to convert them to FLV format and put them into another folder. All I would like is a simple web page that displays all the files in that folder as links, and when you click on the link for the video you want to play, it should play in the same web page inside an embedded Flash/SWF player. Sounds really basic but I'm actually struggling to find a simple solution. Any thoughts appreciated!

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  • SUBST for OSX? Error when trying to map local folder as network drive on Mac OSX 10.9

    - by Taylor Wright
    I would like to map a local folder as a drive (similar to Window's SUBST). One solution I found was to map a shared folder, but I get the following error when using a local folder: There was a problem connecting to the server “MyDrive.local”. This file server is available on your computer. Access the volumes and files locally. I was using this guide: Mapping Drives (Shared Folders) on Mac OS X

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  • Why Solid-State Drives Slow Down As You Fill Them Up

    - by Chris Hoffman
    The benchmarks are clear: Solid-state drives slow down as you fill them up. Fill your solid-state drive to near-capacity and its write performance will decrease dramatically. The reason why lies in the way SSDs and NAND Flash storage work. Filling the drive to capacity is one of the things you should never do with a solid-state drive. A nearly full solid-state drive will have much slower write operations, slowing down your computer.    

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  • USB external drive is not recognized by any OS, how to troubleshoot in Ubuntu?

    - by Breno
    First of all I would like to inform you that I saw a question similar to mine but the error was different, so here's my problem... I have an external HD samsung s2 model of 500GB and a day to day just stopped working, tried in other systems (windows and mac) however are not recognized. In the windows device manager when I insert the usb it states that the device in question are not working properly. Well, in the logs of my ubuntu 4.12 I see the following message when I insert my usb device in: [ 2967.560216] usb 7-2: new full-speed USB device number 2 using uhci_hcd [ 2967.680182] usb 7-2: device descriptor read/64, error -71 [ 2967.904176] usb 7-2: device descriptor read/64, error -71 [ 2968.120227] usb 7-2: new full-speed USB device number 3 using uhci_hcd [ 2968.240207] usb 7-2: device descriptor read/64, error -71 [ 2968.464063] usb 7-2: device descriptor read/64, error -71 [ 2968.680087] usb 7-2: new full-speed USB device number 4 using uhci_hcd [ 2969.092085] usb 7-2: device not accepting address 4, error -71 [ 2969.208155] usb 7-2: new full-speed USB device number 5 using uhci_hcd [ 2969.624076] usb 7-2: device not accepting address 5, error -71 [ 2969.624118] hub 7-0:1.0: unable to enumerate USB device on port 2 [ 4520.240340] usb 7-1: new full-speed USB device number 6 using uhci_hcd [ 4520.364079] usb 7-1: device descriptor read/64, error -71 [ 4520.588109] usb 7-1: device descriptor read/64, error -71 [ 4520.804140] usb 7-1: new full-speed USB device number 7 using uhci_hcd [ 4520.924136] usb 7-1: device descriptor read/64, error -71 [ 4521.148083] usb 7-1: device descriptor read/64, error -71 [ 4521.364105] usb 7-1: new full-speed USB device number 8 using uhci_hcd [ 4521.776237] usb 7-1: device not accepting address 8, error -71 [ 4521.888206] usb 7-1: new full-speed USB device number 9 using uhci_hcd [ 4522.296102] usb 7-1: device not accepting address 9, error -71 [ 4522.296150] hub 7-0:1.0: unable to enumerate USB device on port 1 [ 4749.036104] usb 7-2: new full-speed USB device number 10 using uhci_hcd [ 4749.156209] usb 7-2: device descriptor read/64, error -71 [ 4749.380215] usb 7-2: device descriptor read/64, error -71 [ 4749.596206] usb 7-2: new full-speed USB device number 11 using uhci_hcd [ 4749.716409] usb 7-2: device descriptor read/64, error -71 [ 4749.940110] usb 7-2: device descriptor read/64, error -71 [ 4750.156257] usb 7-2: new full-speed USB device number 12 using uhci_hcd [ 4750.572150] usb 7-2: device not accepting address 12, error -71 [ 4750.684215] usb 7-2: new full-speed USB device number 13 using uhci_hcd [ 4751.100182] usb 7-2: device not accepting address 13, error -71 [ 4751.100224] hub 7-0:1.0: unable to enumerate USB device on port 2 Here is my system: Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 007 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 005 Device 002: ID 08ff:2810 AuthenTec, Inc. AES2810 00:00.0 Host bridge: Intel Corporation Mobile 4 Series Chipset Memory Controller Hub (rev 07) 00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07) 00:02.1 Display controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07) 00:1a.0 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #4 (rev 02) 00:1a.1 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #5 (rev 02) 00:1a.2 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #6 (rev 02) 00:1a.7 USB controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #2 (rev 02) 00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 02) 00:1c.0 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 1 (rev 02) 00:1c.1 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 2 (rev 02) 00:1c.4 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 5 (rev 02) 00:1d.0 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #1 (rev 02) 00:1d.1 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #2 (rev 02) 00:1d.2 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #3 (rev 02) 00:1d.7 USB controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #1 (rev 02) 00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev 92) 00:1f.0 ISA bridge: Intel Corporation ICH9M LPC Interface Controller (rev 02) 00:1f.2 IDE interface: Intel Corporation 82801IBM/IEM (ICH9M/ICH9M-E) 2 port SATA Controller [IDE mode] (rev 02) 00:1f.3 SMBus: Intel Corporation 82801I (ICH9 Family) SMBus Controller (rev 02) 00:1f.5 IDE interface: Intel Corporation 82801IBM/IEM (ICH9M/ICH9M-E) 2 port SATA Controller [IDE mode] (rev 02) 02:01.0 CardBus bridge: Ricoh Co Ltd RL5c476 II (rev ba) 02:01.1 FireWire (IEEE 1394): Ricoh Co Ltd R5C832 IEEE 1394 Controller (rev 04) 02:01.2 SD Host controller: Ricoh Co Ltd R5C822 SD/SDIO/MMC/MS/MSPro Host Adapter (rev 21) 09:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5756ME Gigabit Ethernet PCI Express 0c:00.0 Network controller: Broadcom Corporation BCM4312 802.11b/g LP-PHY (rev 01) Does anyone have any clue what would be the problem?

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  • Executing a C program stored on a windows drive?

    - by bijay prakash singh
    I wrote a simple hello world program but not stored it in Ubuntu's home directory, instead I stored it on one of the Windows drives. (I am using Ubuntu 12.04 alongside of Windows.) When I compiled the program it worked just fine but when I tried to execute it I got an error message "Permission denied". And When I store the program in Ubuntu's home directory I can perfectly compile and execute the program. So please tell me how to overcome this problem??

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  • Impossible to install Ubuntu 10.10 dual boot with Windows 7 on new Acer desktop computer

    - by Don Myers
    My brother has a brand new Acer Desktop with Windows 7. I have done many installs (40+) of Ubuntu starting with 8.10, and have never run into this. I've spent three hours trying to do a dual boot install of 10.10. When you get to the place where you normally would choose to install as a dual boot or overwrite the existing information on the hard drive, that block is just blank. Nothing. No choices even to do a manual partition setup. If you try to go on you get the message "No root file system is defined. Please correct this from the partitioning menu." but there is nothing in the partitioning menu. I tried a good 10.04 disc also. Same thing happens with it. I ran a gparted live cd, and it shows the hard drive as sda with 3 partitions on the original. sda1 is a small partition called PQService. sda2 is another small partition called System Reserved, and GParted says it is the boot partition. sda3 is the main partation with the operating system (Windows 7) and all of the empty space. There is a little unallocated space at the very beginning and very end of the hard drive. If I go to places in the Live CD, it shows a 640 gb hard disk called Acer, but it also shows a 640 gb hard disk called system reserved. They are the same disk. There is just one hard drive. If you click properties in the System Reserved 640 gb, it shows all information as unknown. I had to change the boot order in the bios in order to run the live cd. The hard drive instead of being listed as such is listed as Raid:Raid Ready. Something the way this computer is set up is preventing Ubuntu from being able to identify the hard drive partitions at all to do an install, even if you were not doing a dual boot and just wanted to overwrite Windows. Is this a bug that needs reported? This is a major problem for me and my brother, but also for Ubuntu if new users want to Ubuntu and find they cannot install it.

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  • Why is mount -a not mounting fuse drive properly when executed remotely (via Fabric)?

    - by Jim D
    This is a weird bug and I'm not sure where it's coming from. Here's a quick run down of what I'm doing. I'm trying to mount a FUSE drive to an Amazon EC2 instance running Ubuntu 10.10 using s3fs (FUSE over Amazon). s3fs is compiled from source according to the instructions etc. I've also added an entry to /etc/fstab so that the drive mounts on boot. Here's what /etc/fstab looks like: # /etc/fstab: static file system information. # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 LABEL=uec-rootfs / ext4 defaults 0 0 /dev/sda2 /mnt auto defaults,nobootwait,comment=cloudconfig 0 2 /dev/sda3 none swap sw,comment=cloudconfig 0 0 s3fs#mybucket /mnt/s3/mybucket fuse default_acl=public-read,use_cache=/tmp,allow_other 0 0 So the good news is that this works fine. On reboot the connection mounts correctly. I can also do: $ sudo umount /mnt/s3/mybucket $ sudo mount -a $ mountpoint /mnt/s3/mybucket /mnt/s3/mybucket is a mountpoint Great, right? Well here's the problem. I'm using Fabric to automate the process of building and managing this instance. I noticed I was getting this error message when using Fabric to build s3fs and set up the mount process: mountpoint: /mnt/s3/mybucket: Transport endpoint is not connected I isolated it down the the problem and built a fabric task that reproduces the problem: def remount_s3fs(): sudo("mount -a") Which does: [ec2-xx-xx-xx-xx.compute-1.amazonaws.com] Executing task 'remount_s3fs' [ec2-xx-xx-xx-xx.compute-1.amazonaws.com] sudo: mount -a [And yes, I was sure to unmount it before running this task.] When I check the mount using mountpoint I get: $ mountpoint /mnt/s3/mybucket mountpoint: /mnt/s3/mybucket: Transport endpoint is not connected Done. But if I run sudo mount -a at the command line, it works. Hrm. Here is that fab task output again, this time in full debug mode: [ec2-xx-xx-xx-xx.compute-1.amazonaws.com] Executing task 'remount_s3fs' [ec2-xx-xx-xx-xx.compute-1.amazonaws.com] sudo: sudo -S -p 'sudo password:' /bin/bash -l -c "mount -a" Again, I get that transport endpoint not connected error. I've also tried copying and pasting the exact command run into my ssh session (i.e. sudo -S -p 'sudo password:' /bin/bash -l -c "mount -a") and it works fine. So...that's my problem. Any ideas?

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  • 9/13 Live Webcast!!! Drive Innovation from Big Data Don't delay - register now!

    - by jgelhaus
    Big data solutions can help you find new insights, capitalize on hidden relationships, and deliver new value to your business. But to derive real business value from big data, you need the right tools and the right strategy. Join the live 9/13 Webcast to get an inside look at the benefits of big data and how you can realize them in your own IT infrastructure. We’ll discuss: The defining characteristics of big data Various big data use cases and examples Requirements for new skills and software Highlights of the Oracle big data platform Register now for the live Webcast on 9/13! It's your chance to talk with the Big Data gurus and discover solutions to data challenges that have eluded your data center—until now.

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  • How can I automatically delete /tmp folder on shared drive?

    - by Matt
    We have a /tmp folder that people use for temporary stuff. It can be anything and any file. We want to make it so that this automatically deletes (or preferably MOVES to another folder on the same shared drive) all the files that haven't been accessed in the last two weeks. This should happen weekly on a schedule that I don't have to manually do. Is there software out there that does this? Anyone have a script possibly? Server 2008R2

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  • Mount: "The disk drive for UUID=<uuid for /> is not ready yet or not present."

    - by searchfgold6789
    I recently did the update from 12.04 to 12.10 on my old Dell Latitude CPx laptop (Pentium III). When I rebooted I got this error message with no response from keyboard input. Below it is says Wait to continue, press S to skip mounting, or M for manual recovery. I also see occasional errors pop up on the screen from mountall and Plymouth. I can still get into Recovery Mode. Can anyone shed some light on the matter?

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  • Will installing Ubuntu using Wubi erase Windows?

    - by James Lang
    I have an HP laptop with 2 partitions: C: and D:, with windows 7 installed in the C: drive and D: is the Recovery partition. When I try to install Ubuntu 12.04 LTS using Wubi, it only shows the C: drive for installing and not the D: drive where I wanted to format and install ubuntu. So, if I go ahead and install in the C: drive where windows 7 is already installed, would Wubi erase windows 7? Or it will just install Ubuntu as a program in windows?

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  • What does the directory-name: '~MntWIM' on my Windows 7 / C:\ drive mean?

    - by J Puk
    This '~MntWIM' on my Windows 7 / C:\ drive, is sized: 694 MB (728.418.589 bytes) on harddrive. It contains 3 subdirectories. 1st = Program Files, containg zero volume 2nd = Users, containing zero volume 3rd = Windows, containing 693 MB (726.823.197 bytes) on harddrive It all looks a bit useless to me, so question is: Is it safe to delete the lot? Or does it have an important function there? Hoping for an answer from which I could lern something. B.R. JP

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  • Caching factory design

    - by max
    I have a factory class XFactory that creates objects of class X. Instances of X are very large, so the main purpose of the factory is to cache them, as transparently to the client code as possible. Objects of class X are immutable, so the following code seems reasonable: # module xfactory.py import x class XFactory: _registry = {} def get_x(self, arg1, arg2, use_cache = True): if use_cache: hash_id = hash((arg1, arg2)) if hash_id in _registry: return _registry[hash_id] obj = x.X(arg1, arg2) _registry[hash_id] = obj return obj # module x.py class X: # ... Is it a good pattern? (I know it's not the actual Factory Pattern.) Is there anything I should change? Now, I find that sometimes I want to cache X objects to disk. I'll use pickle for that purpose, and store as values in the _registry the filenames of the pickled objects instead of references to the objects. Of course, _registry itself would have to be stored persistently (perhaps in a pickle file of its own, in a text file, in a database, or simply by giving pickle files the filenames that contain hash_id). Except now the validity of the cached object depends not only on the parameters passed to get_x(), but also on the version of the code that created these objects. Strictly speaking, even a memory-cached object could become invalid if someone modifies x.py or any of its dependencies, and reloads it while the program is running. So far I ignored this danger since it seems unlikely for my application. But I certainly cannot ignore it when my objects are cached to persistent storage. What can I do? I suppose I could make the hash_id more robust by calculating hash of a tuple that contains arguments arg1 and arg2, as well as the filename and last modified date for x.py and every module and data file that it (recursively) depends on. To help delete cache files that won't ever be useful again, I'd add to the _registry the unhashed representation of the modified dates for each record. But even this solution isn't 100% safe since theoretically someone might load a module dynamically, and I wouldn't know about it from statically analyzing the source code. If I go all out and assume every file in the project is a dependency, the mechanism will still break if some module grabs data from an external website, etc.). In addition, the frequency of changes in x.py and its dependencies is quite high, leading to heavy cache invalidation. Thus, I figured I might as well give up some safety, and only invalidate the cache only when there is an obvious mismatch. This means that class X would have a class-level cache validation identifier that should be changed whenever the developer believes a change happened that should invalidate the cache. (With multiple developers, a separate invalidation identifier is required for each.) This identifier is hashed along with arg1 and arg2 and becomes part of the hash keys stored in _registry. Since developers may forget to update the validation identifier or not realize that they invalidated existing cache, it would seem better to add another validation mechanism: class X can have a method that returns all the known "traits" of X. For instance, if X is a table, I might add the names of all the columns. The hash calculation will include the traits as well. I can write this code, but I am afraid that I'm missing something important; and I'm also wondering if perhaps there's a framework or package that can do all of this stuff already. Ideally, I'd like to combine in-memory and disk-based caching.

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  • How can I run Ubuntu if it's not on my main drive?

    - by Stephen
    I have a 120GB SSD and a 750GB HDD in my computer. My SSD has Windows 7 installed and my HDD has Windows 8 installed. When I boot my computer normally, I boot it to my SSD. I went through the installation process, putting Ubuntu on a separate partition on my HDD. When I restarted my computer, it didn't give me an option to boot to Ubuntu. If it helps, I believe I used ext4 and only set it to '/'. If I want to make Ubuntu bootable from my computer, how would I go about doing that?

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  • What's the easiest way to duplicate a portion of a directory structure onto an external drive?

    - by Jon Cage
    I'm trying to move a large chunk of data from one of our servers onto an external drive for delivery to Amazon glacier storage. To do that, I'd like to copy a chunk of the server, preserving the directory structure. I.e. move this: \\MyServer\Some\Longwinded\Path\TheDataIWantToCopy \\MyServer\Some\Longwinded\Path\TheDataIWantToCopy\First bit of data\DataFile1.dat to this: D:\ D:\First bit of data\DataFile1.dat

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