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• Help debugging Sendmail/Mailman configuration issue

  - by inxilpro

  Hi folks, I'm trying to configure a server with Sendmail and Mailman. I've been getting "Broken pipe" errors for a while, and have slowly been debugging. I fixed some permission issues, and changed the user that Mailman expects to be called from, among other things. Finally, I'd gone through everything I could think of, so I added a new test to see if it's the Mailman script or Sendmail that's causing the problem. Here's the error I'm getting now (stripped of timestamps and identifying information): <-- MAIL FROM:[email protected] Authentication-Warning: xxxxx.org: xxxxxxxxxxxxxx.net [xx.xx.xxx.xxx] didn't use HELO protocol --- 250 2.1.0 [email protected]... Sender ok <-- RCPT TO: [email protected] --- 250 2.1.5 [email protected]... Recipient ok <-- DATA --- 354 Enter mail, end with "." on a line by itself [email protected], size=20, class=0, nrcpts=1, msgid=<[email protected]>, proto=SMTP, relay=xxxxxxxxxxxxxx.net [xx.xx.xxx.xxx] --- 250 2.0.0 o6KMg2xZ025804 Message accepted for delivery alias [email protected] => "|/bin/echo foo" SYSERR(root): putbody: write error: Broken pipe 0: fl=0x0, mode=20660: CHR: dev=0/15, ino=776, nlink=1, u/gid=0/0, size=0 1: fl=0x1, mode=20660: CHR: dev=0/15, ino=776, nlink=1, u/gid=0/0, size=0 2: fl=0x1, mode=20660: CHR: dev=0/15, ino=776, nlink=1, u/gid=0/0, size=0 3: fl=0x2, mode=140777: SOCK localhost->[[UNIX: /dev/log]] 5: fl=0x0, mode=100600: dev=8/3, ino=486765, nlink=1, u/gid=0/51, size=5 6: fl=0x8000, mode=100640: dev=8/3, ino=65501, nlink=1, u/gid=0/0, size=12288 7: fl=0x8000, mode=100640: dev=8/3, ino=65501, nlink=1, u/gid=0/0, size=12288 8: fl=0x8000, mode=100640: dev=8/3, ino=65510, nlink=1, u/gid=0/0, size=12288 9: fl=0x8000, mode=100640: dev=8/3, ino=65510, nlink=1, u/gid=0/0, size=12288 10: fl=0x8000, mode=100640: dev=8/3, ino=64814, nlink=1, u/gid=0/51, size=12288 11: fl=0x8000, mode=100640: dev=8/3, ino=64814, nlink=1, u/gid=0/51, size=12288 12: fl=0x1, mode=100600: dev=8/3, ino=486767, nlink=1, u/gid=0/51, size=754 13: fl=0x1, mode=10600: FIFO: dev=0/5, ino=7649785, nlink=1, u/gid=0/51, size=0 14: fl=0x0, mode=10600: FIFO: dev=0/5, ino=7649786, nlink=1, u/gid=0/51, size=0 MCI@0x0: NULL MCI@0x0: NULL to="|/bin/echo foo", [email protected] (8/0), delay=00:00:08, xdelay=00:00:00, mailer=prog, pri=30476, dsn=5.0.0, stat=Service unavailable o6KMsnxX025948: DSN: Service unavailable done; delay=00:00:08, ntries=1 The alias in /etc/aliases is: cmtest: "|/bin/echo foo" As you can see, even when trying to pipe to /bin/echo I still get the same error. But I can't for the life of me figure out what else to check. Normal aliases work fine. Any ideas? Thanks!

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• Getting rsync to move file from source to destination ?

  - by fabien-barbier

  Is rsync is a good choice for my project ? I have to : - copy files from source to destination folder via SSH, - be sure all files are copied, - delete source files after copy. - if I have conflict name, I have to rename files. It looks like I can use option : --remove-source-files (to delete source files) But how rsync manage conflict, can I had rules ? Use case on my project : I run scientific calculation on server A and results are inserted in folder "process", for each calculation I have a repository like this : /process/calc1. Now I would like to transfer repository "/calc1" to server B (I get /process/calc1), and delete "calc1" from server A. ...During another calculation I get "/process/calc2" on server A, the idea is also to move "calc2" in "/process/" directory on server B, then I have now on server B : - /process/calc1 - /process/calc2 (and /process/ on server A is empty). How rsync will manage conflict (on server B) if I have another folder like "/process/calc1" in server A after a new calculation (if "/process/calc1" already exist on server B) ? Is it possible to add rules with rsync, and rename "/process/calc1" by "process/calc1R2" in server B ? And so on (ex:calc1R3) ? Thanks.

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• How to configure autofs5 timeout on per-filesystem basis?

  - by Norman Ramsey

  Because of a show-stopping bug in Debian autofs 4, I just upgraded to autofs5. It is not honoring the timeout option in my auto.master file: /var/autofs/removable /etc/auto.removable --timeout=2 I use this map for thumb drives and so on; I don't want a general default timeout of 2 seconds. I did some digging and although the --timeout option worked in autofs 4, and it appears in some examples on the Web, it is not actually sanctioned (or even mentioned) in the documentation for the auto.master file. So I don't feel I can report the problem as a bug. How can I get autofs5 to timeout after 2 seconds only on designated filesystems? Update: I am using a Debian-packaged autofs5, version 5.0.4-3.2.

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• Issue with multiple bridging for KVM hosts

  - by Henry-Nicolas Tourneur

  I'm using KVM and libvirt on my host (Debian lenny) + 2 bridges per guest (one for mgmt, one for public traffic). That setup isn't stable at all, sometimes I can do pings to a management ip, sometimes not. I don't know if my bridging paramateres are correct, could you check ? or if there is anything wrong ... Please also note that interface on guest doesn't flap and that I got not logs on my host. Of course forwarding is enabled. iface eth3 inet manual auto bond0 iface bond0 inet manual slaves eth1 eth2 pre-up ip link set bond0 up down ip link set bond0 down auto br0 iface br0 inet static address 10.160.0.7 netmask 255.255.255.128 bridge_ports eth3 bridge_fd 9 bridge_hello 2 bridge_maxage 12 bridge_stp off auto br0:1 iface br0:1 inet static address 10.160.0.9 netmask 255.255.255.128 auto br0:2 iface br0:2 inet static address 10.160.0.10 netmask 255.255.255.128 auto br1 iface br1 inet static address 217.4.40.242 netmask 255.255.255.240 gateway 217.4.40.241 pre-up /etc/network/firewall start bridge_ports bond0 bridge_fd 9 bridge_hello 2 bridge_maxage 12 bridge_stp off auto br1:1 iface br1:1 inet static address 217.4.40.252 netmask 255.255.255.240 auto br1:2 iface br1:2 inet static address 217.4.40.253 netmask 255.255.255.240

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• How do you find the parent process of a zombie process?

  - by Jack

  How do you find the parent process of zombie processes? When the child process is something where the parent is not entirely obvious... Is there some way to list processes in tree format or something?

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• My control key doesn't work, how do I fix it??

  - by Blaine LaFreniere

  My control key on the right doesn't work how it should. E.g. Right ctrl + T won't open new tabs in firefox, right ctrl + w won't switch windows in vim, etc. I know the key isn't physically broken, because xev shows that the right ctrl key generates events, but it just isn't responding as I expect it to in applications. Screenshot: http://i46.tinypic.com/33w1h76.png I tried Kim's answer but it still doesn't work. blaine@blaine-laptop ~ $ xmodmap -pke | grep 105 keycode 105 = Control_R Control_R Control_R Control_R Control_R Tried to map as Control_L as well, didn't work. The computer is a laptop, I am unable to plug the keyboard in to another computer.

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• Ubuntu and mysql server. Something isnt allowing me to connect

  - by acidzombie24

  I have a question about mysql settings http://serverfault.com/questions/94054/remote-connections-and-mysql-on-ubuntu/94088#94088 now i want to figure out why i cannot connect. I made sure bind-address was commented out. I can ping the server within the VM but i cannot ping it from within the VM using mysqladmin --protocol=tcp --host=self_ip ping. I also followed along and check if my ports were open and they look like they are. I setup samba on that VM and can access that with no problem as well. It looks like ubuntu does not have a firewall either (i figured this out before) so i am stumped why the server isnt allowing my connection. Apparently the config file works on another person side http://www.pastie.org/742545 I am using Ubuntu 6.06 LTS just because of 'support' reasons. So hopefully this will be 'easy'?

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• Making libmagic/file detect .docx files

  - by Jonatan Littke

  As seen elsewhere, docx, xlsx and pttx are ZIPs. When uploading them to my web application, file (via libmagic andpython-magic) detects them as being ZIP. I store the contents of the file as a blob in the database, but naturally I don't want to trust the user with what kind of file type this is. So I would like to trust file for and automatically generate a filename during download. I know one can modify /etc/magic but the format (magic(5)) is way too complicated for me. I found a bug report on the issue at Debian bugs but since it's from 2008 it doesn't seem to be fixed any time soon. I guess my only other alternative is to indeed trust the user (but still store the contents as a blob) and only check the file extension based on the file name. This way I can disallow some extensions and allow others. And when the user re-downloads his file, he can have it in whatever way he uploaded it. But this solution is insecure if the file is shared with others, since you can simply rename the file to allow uploading it. Any ideas? Lastly, I found a list of magic numbers for docx etc, but I'm unable to convert these into the magic(5) format.

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• Why does ganglia think my host is down?

  - by NZKoz

  I have ganglia set up to monitor our staging server, it's working great but I'm confused by the definition of 'down' to ganglia. There's a single node, running gmetad, gmond and the web frontend, but some small percentage of the time the web frontend shows some confusing output. Despite the fact that it's a single server in the cluster, and that server is the one serving the web interface, the dashboard output insists that the host is down. Then below that it has a graph which shows 50% down, 50% up. You can see an example of this here: http://i.imgur.com/MCWaS.jpg There's obviously something confusing ganglia somewhere, but I'm not sure where to start looking. Unfortunately googling for any combination of 'ganglia' 'down' 'metric name' seems return nothing but other people's ganglia installations displaying the same nonsense. Any tips on where to start looking would be greatly appreciated

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• How to get an inactive RAID device working again?

  - by Jonik

  After booting, my RAID1 device (/dev/md_d0 *) sometimes goes in some funny state and I cannot mount it. * Originally I created /dev/md0 but it has somehow changed itself into /dev/md_d0. # mount /opt mount: wrong fs type, bad option, bad superblock on /dev/md_d0, missing codepage or helper program, or other error (could this be the IDE device where you in fact use ide-scsi so that sr0 or sda or so is needed?) In some cases useful info is found in syslog - try dmesg | tail or so The RAID device appears to be inactive somehow: # cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md_d0 : inactive sda4[0](S) 241095104 blocks # mdadm --detail /dev/md_d0 mdadm: md device /dev/md_d0 does not appear to be active. Question is, how to make the device active again (using mdmadm, I presume)? (Other times it's alright (active) after boot, and I can mount it manually without problems. But it still won't mount automatically even though I have it in /etc/fstab: /dev/md_d0 /opt ext4 defaults 0 0 So a bonus question: what should I do to make the RAID device automatically mount at /opt at boot time?) This is an Ubuntu 9.10 workstation. Background info about my RAID setup in this question. Edit: My /etc/mdadm/mdadm.conf looks like this. I've never touched this file, at least by hand. # by default, scan all partitions (/proc/partitions) for MD superblocks. # alternatively, specify devices to scan, using wildcards if desired. DEVICE partitions # auto-create devices with Debian standard permissions CREATE owner=root group=disk mode=0660 auto=yes # automatically tag new arrays as belonging to the local system HOMEHOST <system> # instruct the monitoring daemon where to send mail alerts MAILADDR <my mail address> # definitions of existing MD arrays # This file was auto-generated on Wed, 27 Jan 2010 17:14:36 +0200 In /proc/partitions the last entry is md_d0 at least now, after reboot, when the device happens to be active again. (I'm not sure if it would be the same when it's inactive.) Resolution: as Jimmy Hedman suggested, I took the output of mdadm --examine --scan: ARRAY /dev/md0 level=raid1 num-devices=2 UUID=de8fbd92[...] and added it in /etc/mdadm/mdadm.conf, which seems to have fixed the main problem. After changing /etc/fstab to use /dev/md0 again (instead of /dev/md_d0), the RAID device also gets automatically mounted!

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• Have Ubuntu auto-connect to wireless AP without logging in

  - by dragonmantank

  We have an ubuntu box set up to do some monitoring but due to the placement are unable to run CAT5 to the box itself. I have an Atheros PCI card that works great as long as someone is logged into Gnome and it doesn't disconnect from the AP during that time. Is there a way to have Ubuntu connect to the AP during boot, and always reconnect if it finds a signal from a specified AP? The box would have a static IP and only connecting to a specific AP using WEP.

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• IPv6 working fine, IPv4 throws OpenSSL error

  - by jippie

  I am building a webserver ( http://blog.linformatronics.nl/ ), which functions just fine on both IPv4 and IPv6 and when using a non-SSL connection. However when I connect to it through https, IPv6 works as expected, but an IPv4 connection throws a client side error. Server side logs are empty for the IPv4/https connection. Summarized in a table: | http | https -----+-------+------------------------------------------------------- IPv4 | works | OpenSSL error, failed. No server side logging. -----+-------+------------------------------------------------------- IPv6 | works | self signed certificate warning, but works as expected Apparently the SSL tunnel isn't even set up, which accounts for the Apache logs being empty. But why does it work fine for IPv6 and fail for IPv4? My question is why is this OpenSSL error being thrown and how can I solve it? Below is some extra information about the setup. IPv6 https Command used to reproduce IPv6/https behaviour: $ wget --no-check-certificate -O /dev/null -6 https://blog.linformatronics.nl --2012-11-03 15:46:48-- https://blog.linformatronics.nl/ Resolving blog.linformatronics.nl (blog.linformatronics.nl)... 2001:980:1b7f:1:a00:27ff:fea6:a2e7 Connecting to blog.linformatronics.nl (blog.linformatronics.nl)|2001:980:1b7f:1:a00:27ff:fea6:a2e7|:443... connected. WARNING: cannot verify blog.linformatronics.nl's certificate, issued by `/CN=localhost': Self-signed certificate encountered. WARNING: certificate common name `localhost' doesn't match requested host name `blog.linformatronics.nl'. HTTP request sent, awaiting response... 200 OK Length: 4556 (4.4K) [text/html] Saving to: `/dev/null' 100%[=======================================================================>] 4,556 --.-K/s in 0s 2012-11-03 15:46:49 (62.5 MB/s) - `/dev/null' saved [4556/4556] IPv4 https Command used to reproduce IPv6/https behaviour: $ wget --no-check-certificate -O /dev/null -4 https://blog.linformatronics.nl --2012-11-03 15:47:28-- https://blog.linformatronics.nl/ Resolving blog.linformatronics.nl (blog.linformatronics.nl)... 82.95.251.247 Connecting to blog.linformatronics.nl (blog.linformatronics.nl)|82.95.251.247|:443... connected. OpenSSL: error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol Unable to establish SSL connection. Notes I am on Ubuntu Server 12.04.1 LTS

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• Bacula Director and Storage in LAN

  - by B14D3

  I have two networks LAN and DMZ.. Machines in DMZ are accesible from internet ( only over http). In LAN I have servers that see all LAN and all DMZ machines but machinse from DMZ don't see any LAN servers. Machines in LAN have access only to all LAN and DMZ, no direct access to internet and no access from internet. DMZ <------ LAN DMZ ----X--->LAN I'm planning to configure Bacula as major backup system. My plan is to install Bacula Director and Storage deamon on the same server in LAN for safety reasons. So my question is: Will this configuration work, is it posible for bacula director and storage deamon installed on server in LAN to makes backup servers that are in my DMZ? Or in this network configuration Bacula should be in DMZ? (If yes will I can backup with it servers in LAN ?)

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• cloud computing ? Eucalyptus

  - by neolix

  Hi Greeting!! I want to setup small cloud computing using our old 2 core server system? we are new to cloud system we have google for the same. We are looking host VM's on top any one has done pls share me doc or how to ? we have 50 plus server which we are not using. 2 core each 4GB RAM, 1TB HDD centos is my base os we looking host windows. Right now we can use this server only paravirtualization ignore my english Thanks

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• SSH sometimes screws up connection when terminal overflows?

  - by SeveQ

  I've got a problem with SSH on a Debian Lenny based server (it's a vHost within a Xen environment, booted on a Xen kernel). I hope someone can help me with this. The SSH connection seems somehow getting screwed up frequently when the terminal overflows (new lines beyond the bottom of the terminal, usually forcing it to scroll). The connection gets lost but not regularly disconnected. It nearly always happens when I do the following: an existing SSH connection gets disconnected (regularly) I order putty to reestablish the connection login-prompt appears at the very bottom of the putty terminal window I enter my login-name, press the enter key I'm asked for the password, I enter it, press the enter key and BOOM! Nothing more happens. I have to reconnect again. So it is reproducable. I'm not totally sure if the connection crashes before or after I enter the password. Furthermore it also happens when there is much text to be displayed (for example when I compile something or do an ls -l on a directory with many entries). Using 'screen', however, helps to reduces the frequency of occurence but doesn't solve the problem completely. It's occurence is independent from which terminal software I use. I mostly use putty but it also happens with other clients. I certainly hope somebody can help me solving this problem. Thanks in advance! //edit: I've just made a Wireshark trace of the ssh connection and there is nothing, I repeat, nothing different between the working and the failing connection (at least aside from frame numbers, ports and times that obviously can't be equal). This leads me to the assumption that the error has to happen on the server's side.

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• "Clone" a Virtuozzo VPS

  - by Alex Takitani

  We have a rhel running on a VPS, I want to bring it to our network server, a vmware esx. Is it possible? Any advice would be great, tks!

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• Ubuntu Desktop system restore ?

  - by neolix

  Hello Geeks, We are using all the desktop ubuntu 8.04 to 10.04, we are looking same thing like system resorting to back date like windows feature. Around 500 desktop and 79 server we want to setup. Thanks

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• How to repair unbootable Fedora install

  - by Cerin

  How do you repair/reinstall Fedora without deleting any existing partitions or data? I was attempting to upgrade some old Fedora 13 servers to 17, following the instructions in the wiki. After the 14-15 upgrade, rebooting resulted in the output: Dropping to debug shell. sh: can't access tty; job control turned off dracut:/# Running dmesg also shows: dracut Warning: No root device "block:/dev/mapper/VolGroup-lv_root" found Googling shows this error is typically related to some weird RAID issues, but my server is a virtual machine not using any RAID. Using a rescue CD, I can chroot /mnt/sysimage, and all packages and data still seems to be there. How do I make the system bootable again?

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• How to prioritize openvpn traffic?

  - by aditsu

  I have an openvpn server, with one network interface. VPN traffic is extremely slow. I tried to do traffic control with this configuration (currently): qdisc del dev eth0 root qdisc add dev eth0 root handle 1: htb default 12 class add dev eth0 parent 1: classid 1:1 htb rate 900mbit #vpn class add dev eth0 parent 1:1 classid 1:10 htb rate 1500kbit ceil 3000kbit prio 1 #local net class add dev eth0 parent 1:1 classid 1:11 htb rate 10mbit ceil 900mbit prio 2 #other class add dev eth0 parent 1:1 classid 1:12 htb rate 500kbit ceil 1000kbit prio 2 filter add dev eth0 protocol ip parent 1:0 prio 1 u32 match ip sport 1194 0xffff flowid 1:10 filter add dev eth0 protocol ip parent 1:0 prio 2 u32 match ip dst 192.168.10.0/24 flowid 1:11 qdisc add dev eth0 parent 1:10 handle 10: sfq perturb 10 qdisc add dev eth0 parent 1:11 handle 11: sfq perturb 10 qdisc add dev eth0 parent 1:12 handle 12: sfq perturb 10 But it's still extremely slow. I have an imaps connection that keeps transferring data continuously (I successfully limited the rate) but with openvpn I can't seem to get more than about 100kbit/s The internet connection speed is about 3mbit/s (symmetric) What could be the problem? Does the sport filter work for udp?

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• NIC bonding with two uplinks

  - by Karolis T.

  Is bonding the preferred way of implementing ISP redundancy? In the texts I've seen, bond device has a netmask, gateway of it's own. How can this be obtained if there are two different gateways from two uplinks, which one to choose? Do I need any special routing rules to go with it or does simply configuring separate interfaces (using Debian, /etc/network/interfaces), i.e eth1, eth2 for their corresponding uplinks and bonding them to bond0 handle routing automatically? If I want to NAT client machines, do they use bond device's IP as a gateway? Does the bond0 device is the device that goes into iptables nat rules? Thanks

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• Simple mdadm RAID 1 not activating spare

  - by Nick Liu

  I had created two 2TB HDD partitions (/dev/sdb1 and /dev/sdc1) in a RAID 1 array called /dev/md0 using mdadm on Ubuntu 12.04 LTS Precise Pangolin. The command sudo mdadm --detail /dev/md0 used to indicate both drives as active sync. Then, for testing, I failed /dev/sdb1, removed it, then added it again with the command sudo mdadm /dev/md0 --add /dev/sdb1 watch cat /proc/mdstat showed a progress bar of the array rebuilding, but I wouldn't spend hours watching it, so I assumed that the software knew what it was doing. After the progress bar was no longer showing, cat /proc/mdstat displays: md0 : active raid1 sdb1[2](S) sdc1[1] 1953511288 blocks super 1.2 [2/1] [U_] And sudo mdadm --detail /dev/md0 shows: /dev/md0: Version : 1.2 Creation Time : Sun May 27 11:26:05 2012 Raid Level : raid1 Array Size : 1953511288 (1863.01 GiB 2000.40 GB) Used Dev Size : 1953511288 (1863.01 GiB 2000.40 GB) Raid Devices : 2 Total Devices : 2 Persistence : Superblock is persistent Update Time : Mon May 28 11:16:49 2012 State : clean, degraded Active Devices : 1 Working Devices : 2 Failed Devices : 0 Spare Devices : 1 Name : Deltique:0 (local to host Deltique) UUID : 49733c26:dd5f67b5:13741fb7:c568bd04 Events : 32365 Number Major Minor RaidDevice State 1 8 33 0 active sync /dev/sdc1 1 0 0 1 removed 2 8 17 - spare /dev/sdb1 I've been told that mdadm automatically replaces removed drives with spares, but /dev/sdb1 isn't being moved into the expected position, RaidDevice 1. UPDATE (30 May 2012): A badblocks destructive read-write test of the entire /dev/sdb yielded no errors as expected; both HDDs are new. As of the latest edit, I assembled the array with this command: sudo mdadm --assemble --force --no-degraded /dev/md0 /dev/sdb1 /dev/sdc1 The output was: mdadm: /dev/md0 has been started with 1 drive (out of 2) and 1 rebuilding. Rebuilding looks like it's progressing normally: md0 : active raid1 sdc1[1] sdb1[2] 1953511288 blocks super 1.2 [2/1] [U_] [>....................] recovery = 0.6% (13261504/1953511288) finish=2299.7min speed=14060K/sec unused devices: <none> I'm now waiting on this rebuild, but I'm expecting /dev/sdb1 to become a spare just like the five or six times that I've tried rebuilding before. UPDATE (31 May 2012): Yeah, it's still a spare. Ugh! UPDATE (01 June 2012): I'm trying Adrian Kelly's suggested command: sudo mdadm --assemble --update=resync /dev/md0 /dev/sdb1 /dev/sdc1 Waiting on the rebuild now... My questions are: Why isn't the spare drive becoming active sync? How can I make the spare drive become active?

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• One incorrect SSH login attempt locks me out for an hour...

  - by Legend

  I've never observed this problem neither did any of my colleagues trying to SSH into the same system. If I try logging into my server using a wrong username and then press ^C to terminate or exhaust my password attempts, I am locked out for at least an hour. Is there something I can do on my end to fix this problem?

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• Can enabling a RAID controller's writeback cache harm overall performance?

  - by Nathan O'Sullivan

  I have an 8 drive RAID 10 setup connected to an Adaptec 5805Z, running Centos 5.5 and deadline scheduler. A basic dd read test shows 400mb/sec, and a basic dd write test shows about the same. When I run the two simultaneously, I see the read speed drop to ~5mb/sec while the write speed stays at more or less the same 400mb/sec. The output of iostat -x as you would expect, shows that very few read transactions are being executed while the disk is bombarded with writes. If i turn the controller's writeback cache off, I dont see a 50:50 split but I do see a marked improvement, somewhere around 100mb/s reads and 300mb/s writes. I've also found if I lower the nr_requests setting on the drive's queue (somewhere around 8 seems optimal) I can end up with 150mb/sec reads and 150mb/sec writes; ie. a reduction in total throughput but certainly more suitable for my workload. Is this a real phenomenon? Or is my synthetic test too simplistic? The reason this could happen seems clear enough, when the scheduler switches from reads to writes, it can run heaps of write requests because they all just land in the controllers cache but must be carried out at some point. I would guess the actual disk writes are occuring when the scheduler starts trying to perform reads again, resulting in very few read requests being executed. This seems a reasonable explanation, but it also seems like a massive drawback to using writeback cache on an system with non-trivial write loads. I've been searching for discussions around this all afternoon and found nothing. What am I missing?

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• Make GRUB automatically boot Ubuntu

  - by Matt Robertson

  I am running a dual-boot with Ubuntu (10.10) and Windows 7. Recently I edited my /boot/grub/grub.cfg file to only show one version of Ubuntu (as opposed to several kernel versions) and Windows, simply by commenting out all other menu entries. My question is if I can edit GRUB to just boot a specific entry automatically. I tried removing all other menu entries, but GRUB still showed the menu with only one entry. I've also considered just setting the timeout to either 0 or 1 second, as this would basically achieve the same thing. What is the best way to do this?

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• Simple NNTP client for Ubuntu

  - by Alexander Gladysh

  I need to download a particular NNTP group. I do not need to setup any crons, put group contents in /opt and other stuff. Just run <fetch-nntp> <server> <group-name> <output-dir> and be done with it without putting a lot of garbage in the system. If that <fetch-nntp> would not fetch the same messages on the second run — fine. But I can live without it. All NNTP clients that I've looked at are trying to be a NNTP server as well. Is there something simpler that is suitable for my needs?

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