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• Vserver: secure mails from a hacked webservice

  - by lukas

  I plan to rent and setup a vServer with Debian xor CentOS. I know from my host, that the vServers are virtualized with linux-vserver. Assume there is a lighthttpd and some mail transfer agent running and we have to assure that if the lighthttpd will be hacked, the stored e-mails are not readable easily. For me, this sounds impossible but may I missed something or at least you guys can validate the impossibility... :) I think basically there are three obvious approaches. The first is to encrypt all the data. Nevertheless, the server would have to store the key somewhere so an attacker (w|c)ould figure that out. Secondly one could isolate the critical services like lighthttpd. Since I am not allowed to do 'mknod' or remount /dev in a linux-vserver, it is not possible to setup a nested vServer with lxc or similar techniques. The last approach would be to do a chroot but I am not sure if it would provide enough security. Further I have not tried yet, if I am able to do a chroot in a linux-vserver...? Thanks in advance!

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• Kickstart installation from USB -- Kickstart location

  - by dooffas

  After managing to get a Fedora ISO to rebuild successfully (for a USB stick) after adding a kickstart file (http://serverfault.com/questions/548405/), I now have an issue with locating the kickstart file on the USB media. When this is done from a CDROM you can simply kickckstart by adding this parameter to boot: linux ks=cdrom This will kickstart (providing the kickstart file is named ks.cfg and is in the root of the disk). Now, obviously this will be different for the USB drive, so from my research, I assumed that this line would do the job: linux ks=hd:sdb1:/ks.cfg Evidently this does not work. I get an error informing me this drive is already mounted and cannot be remounted. EDIT: Actual error message: mount: /dev/sdb1 is already mounted or /run/install/tmpmnt0 busy Warning: Can't get kickstart from /dev/sdb1:/ks.cfg To test that the syntax was correct I placed the kickstart file on another USB stick and loaded the same command to grab ks.cfg from the new location: linux ks=hd:sdc1:/ks.cfg This does work (providing USB sticks are mounted in order, boot - sdb1, kickstart - sdc1). The install will kickstart and complete the install with no issue. Obviously having to use 2 pen drives is somewhat frustrating and unreliable. Is there a way around this?

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• Adding PHP to Apache

  - by user528451

  Where I work, we use ancient technology that belongs in a museum. Further I have to get everything done through system admins. They are telling me in order to get PHP, they will need to upgrade the operating system as well as the Apache version. lcas100[67]% uname -a Linux lcas100 2.6.9-11.ELsmp #1 SMP Fri May 20 18:26:27 EDT 2005 i686 i686 i386 GNU/Linux lcas100[68]% cat /etc/*-release LSB_VERSION="1.3" Red Hat Enterprise Linux AS release 4 (Nahant) lcas100[75]% /ots/apache/bin/httpd -v Server version: Apache/1.3.31 (Unix) Server built: Nov 3 2004 18:47:31 This doesn't make sense to me because apparently Apache 1.3.x supports PHP: http://php.net/manual/en/install.unix.apache.php Furthermore, we have another machine that runs PHP and is running the exact same OS and OS version. The reason I want it on the former machine is because it is mounted on a different file system. Lastly they tell me that all software the Apache webserver runs will need to be reinstalled/recompiled (assuming an Apache upgrade WAS needed). I am not even sure about this. Are they full of it? Thanks

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• Get details / solve issue with a kernel panic?

  - by Joseph

  I have a Lenovo T430 running Linux Mint 13 (MATE): joseph:~$ uname -a Linux joseph-T430-LM 3.2.0-23-generic #36-Ubuntu SMP Tue Apr 10 20:39:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux I installed Mint immediately after getting the laptop about two weeks ago, and have noticed that about once a day, the computer will completely freeze up- I can't use Ctrl+Alt+Backspace to restart X, I can't use Ctrl+Alt+F1 to get a text only terminal, can't move mouse, can't type, and if any music was playing it just gets stuck in about a 1-second loop. There is a Windows partition, but I haven't had any issues in Windows. I couldn't find a common thread between the freezes, they were seemingly random (sometimes right after I clicked the mouse, sometimes not; sometimes with Pandora/flash being used, sometimes not, etc). I assume they're kernel panics since it completely locks up, but the laptop doesn't have a capslock or scroll lock LED. It is on a dock and I do have a USB keyboard, but the scroll lock/capslock lights do not flash when it happens (not sure if this is indicating its not a kernel panic, or if the kernel panic just wouldn't illuminate the LEDs on a usb keyboard attached to a laptop dock). This was annoying but not terrible. However, I've found a way to reproduce it. I have a particular CSV file that when I open up in LibreOffice Calc and scroll around, the same thing happens- complete lock up. I really need to use this file, so I'd like to fix the issue, but at the least it's given me a test case to work with. So, having a case where I can cause this issue, what can I do to better find out what's going on? I've looked in /var/log/syslog but haven't found anything seemingly useful. Any thoughts?

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• How install ImageMagic 6.6.2 on Ubuntu 10.04 (lucid)

  - by Svyatoslavik

  How install ImageMagic 6.6.2 on Ubuntu 10.04 (lucid) Problem that lucid have old ImageMagic version(6.5.2) Its very important because me need work with SVG grafics, In my local pc I have ubuntu 11.04 and ImageMagic 6.6.2 and all work fine, In server I have 6.5... and I have problem. Reinstall ubuntu to 11.* this is no solution. I tried change /etc/apt/source.list from ubuntu 10.04 (lucid) to list from ubuntu 11.04 (natty) and update ImageMagic. After this action I have ImageMagic 6.6.2 (I looked phpinfo()) but ImageMagick is not work now. If I try do any action I get error: [error] 8996#0: *19983 FastCGI sent in stderr: "PHP Fatal error: Uncaught exception 'ImagickException' with message 'no decode delegate for this image format `/tmp/magick-XXnYKWKC' @ error/constitute.c/ReadImage/532' How it fix? Or how return to old version imagemagick? Problem if I try install from sources: /tmp/image/ImageMagick-6.7.2-7# ./configure configuring ImageMagick 6.7.2-7 checking build system type... i686-pc-linux-gnu checking host system type... i686-pc-linux-gnu checking target system type... i686-pc-linux-gnu checking whether build environment is sane... yes checking for a BSD-compatible install... /usr/bin/install -c checking for a thread-safe mkdir -p... /bin/mkdir -p checking for gawk... no checking for mawk... mawk checking whether make sets $(MAKE)... yes checking for style of include used by make... GNU checking for gcc... gcc checking whether the C compiler works... no configure: error: in `/tmp/image/ImageMagick-6.7.2-7': configure: error: C compiler cannot create executables See `config.log' for more details /tmp/image/ImageMagick-6.7.2-7#

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• what is uninstall procedure for software installed via "make install" on CentOS 6.2

  - by gkdsp

  I installed OCILIB on my CentOS 6.2 server some time ago, and now I want to install a newer version. The vendor requires an uninstall, but doesn't provide instructions. I'm guessing that's because it's trivial for people with a Linux background. http://orclib.sourceforge.net/doc/html/group_g_install.html If I installed this software using: step 1: # ./configure --with-oracle-headers-path=/usr/include/oracle/11.2/client64 --with-oracle-lib-path=/usr/lib/oracle/11.2/client64/lib step 2: # make step 3: # su root step 4: # make install step 5: # gcc -g -DOCI_IMPORT_LINKAGE -DOCI_CHARSET_ANSI -L/usr/lib/oracle/11.2/client64/lib -lclntsh -L/usr/local/lib -locilib conn.c -o conn How would I go about uninstalling this? I tried following this http://www.cyberciti.biz/faq/delete-uninstall-software-linux-commands/ but nothing was found on my disk using rpm -qa *oci* or yum list *oci*. Maybe since it wasn't installed with yum or rpm then I shouldn't expect either of these to find it. Are there generic instructions for uninstalling software on Linux that I could use, or do the instructions really depend on the specific software? Any help much appreciated.

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• NATing IPv4 while routing IPv6

  - by Hugo

  I've the following setup: client(s) <---> (eth0) router (eth1) <---> wan I have a static IPv4 address and a /48 IPv6 address block. I need to connect all the clients to (wan). Each client will have it's own public IPv6. Meanwhile, I need to NAT those same clients over to (wan). Everything IPv4-related and the NAT are working fine. The IPv6 communication to/from (eth0)<-(clients) works fine, as does the IPv6 communication from (eth1)<-(wan) works fine. To provide IPv6 to all my clients, I've thought of too choices: Having the router as a gateway, which different IP on each interface. This sounds like I need to tell my ISP to route the entire block through that single IP, so it's not really an option. Transparently pass IPv6 packets to/from eth0<-eth1, so all clients can communicate with the upstream gateway (I would actually have a switch here if it weren't for the need to remain IPv4 compatible). So, since I've opted for the second choice, I'm in doubt: How can I pass all IPv6 traffic from eth0 to eth1 transparently? What I need is a level 3 bridge, but linux's bridgeutils create a level 2 bridge (which would bridge ipv4 as well, and I can't have that). This is a DD-WRT device, but it's pretty much an embeded linux, so most suggestions that would work on linux are welcome. Thanks.

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• How to install subversion on 1&1 server with windows?

  - by Miles M.

  I would like to start using Unfuddle for my project on 1&1 server. I never used subversion and core control before. So, I read a lot of documentation about it but each time, I get lost at the very beginning : I've downloaded the latest version of subversion. But on every tutorial, the way to follow is different. First I sae, on a lot of tuts, that you have to enter command lines. Is that ONLY for Linux ? Like here : http://chwalisz.org/2007/08/05/subversion-on-11-shared-hosting/ I also find something completely different on some website, I think (correct me if I'm wrong) it is the Windows tuts, deeply different frm the linu one. So I found that : http://www.codinghorror.com/blog/2008/04/setting-up-subversion-on-windows.html http://geekswithblogs.net/emanish/archive/2006/06/14/81905.aspx http://better-scm.shlomifish.org/subversion/Svn-Win32-Inst-Guide.html And I don t understand : Do I still have to put the sibversion file on the server ? Do I have to install Apach ? where, on my computer or on my server ? I'm working ith WampServer so I thing I have already Apach installed right ? When they say it is for Windows, do they mean it is for windows servers or for your own OS ? 'Cause my servers are on linux. How could I install Subversion on a 1&1 linux server from my W7 OS computer ? Thanks, that's a lot of question but that realle messy in my mind, I can't find something clear ..

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• X11 performance problem after upgrading from Centos3 to Centos5 with an ATI Rage XL

  - by Marcelo Santos

  After upgrading a computer from Centos3 to Centos5 an application that does a lot of scrolling took a very high performance hit. top tells me that X is using a lot of CPU and that was not happening before. The machine has an ATI Rage XL with 8MB and X is using the ati driver as there is no proprietary ATI driver for this board on linux. The xorg.conf: Section "Device" Identifier "Videocard0" Driver "ati" EndSection Section "Screen" Identifier "Screen0" Device "Videocard0" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 Modes "1024x768" "800x600" "640x480" EndSubSection EndSection Section "DRI" Group 0 Mode 0666 EndSection A similar machine that still has Centos3 installed is able to start DRI on the X server while this one is not, this is the Xorg.0.log for the Centos5 machine: drmOpenDevice: node name is /dev/dri/card0 drmOpenDevice: open result is -1, (No such device or address) drmOpenDevice: open result is -1, (No such device or address) drmOpenDevice: Open failed drmOpenDevice: node name is /dev/dri/card0 drmOpenDevice: open result is -1, (No such device or address) drmOpenDevice: open result is -1, (No such device or address) drmOpenDevice: Open failed [drm] failed to load kernel module "mach64" (II) ATI(0): [drm] drmOpen failed (EE) ATI(0): [dri] DRIScreenInit Failed (II) ATI(0): Largest offscreen areas (with overlaps): (II) ATI(0): 1024 x 1279 rectangle at 0,768 (II) ATI(0): 768 x 1280 rectangle at 0,768 (II) ATI(0): Using XFree86 Acceleration Architecture (XAA) Screen to screen bit blits Solid filled rectangles 8x8 mono pattern filled rectangles Indirect CPU to Screen color expansion Solid Lines Offscreen Pixmaps Setting up tile and stipple cache: 32 128x128 slots 10 256x256 slots (==) ATI(0): Backing store disabled (==) ATI(0): Silken mouse enabled (II) ATI(0): Direct rendering disabled (==) RandR enabled I also tried using EXA instead of XAA and setting: Option "AccelMethod" "XAA" Option "XAANoOffscreenPixmaps" "true" uname -a Linux sir5.erg.inpe.br 2.6.18-128.7.1.el5 #1 SMP Mon Aug 24 08:20:55 EDT 2009 i686 i686 i386 GNU/Linux rpm -qa | grep xorg-x11-server xorg-x11-server-utils-7.1-4.fc6 xorg-x11-server-sdk-1.1.1-48.52.el5 xorg-x11-server-Xvfb-1.1.1-48.52.el5 xorg-x11-server-Xnest-1.1.1-48.52.el5 xorg-x11-server-Xorg-1.1.1-48.52.el5 The drmOpenDevice error continues when using the suggested Option "AIGLX" "true".

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• APACHE - PHP - Bounce emails

  - by user1179459

  I want to improve our mail server lists by handling all the bounces we get in our websites. I have a website which has over 8000+ users and another website which as over 1500+ users, they are emailed various notifications every second, ie. job alerts, email alerts, I am using POP connections with EXIM on APACHE server, most scripts are based on PHP language generates email on the fly. Problems i have But some users has registered long time ago and now quite few has bounce email address Some users register with dummy emails like [email protected] which never existed but a valid email address, any chance of stopping this without asking them login to the email account and clicking links which dont work most times.. (too annoying to the end user) Server is sending unnecessary emails can be avoided if i know they dont exists ? Solutions i need to have Is there a way i can download the bounce email list somewhere (WHM/Cpanel), i know exim mail has it but its not readable (i need a file like CSV or something similar to scan them over and write a php script to delete the users from the database ?) I need to know if there is any function in the PHP that can check the existence of the email address on the fly ? so that i can set the email send function in the mailer class to check before it sends out. On the server will bouncing emails are going to eatup lots of server resources ? like memory/cpu on processing them ? or are they are minimal where we dont have to worry about this at all ? May be a opensoruce or linux software to capture them and view them in a report basis and cleaning them up ? I am not a linux expert or server admin but i do lot of PHP coding, so please be descriptive of the solutions specially if they are linux commands Thank you!

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• Use Alladin eToken with ThunderBird and other tool

  - by Yurij73

  I'm looking for an example on how to setup the eToken PRO Java device to work with Mozilla Thunderbird and with other Linux tool such as PAM logon. I installed distributed pkiclient-5.00.28-0.i386.RPM from the official product page eToken Pro but that tool only handles importing/exporting certificates on the device. I read a glance an old HOWTO from eToken on Linux, but I couldn't install pkcs11-lib for this device as recommended for Thunderbird use this crypto device. It seems my usb token isn't listed in system, unless lsusb show it, so that is the matter modutil -list -dbdir /etc/pki/nssdb Listing of PKCS #11 Modules NSS Internal PKCS #11 Module Blockquote slots: 2 slots attached Blockquote status: loaded Blockquote slot: NSS User Private Key and Certificate Services Blockquote token: NSS Certificate DB Blockquote CoolKey PKCS #11 Module Blockquote library name: libcoolkeypk11.so Blockquote slots: 1 slot attached Blockquote status: loaded Blockquote slot: AKS ifdh [Main Interface] 00 00 token: is my token absent? on other hand i don't know which module is convenient to Java Pro, does CoolKey does all the job well? It seems Java token is too new hardware for Linux? there is excerpt from /etc/pam_pkcs11.conf #filename of the PKCS #11 module. The default value is "default" use_pkcs11_module = coolkey; screen_savers = gnome-screensaver,xscreensaver,kscreensaver pkcs11_module coolkey { module = libcoolkeypk11.so; description = "Cool Key"`

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• Openfiler crashing without cause or leaving any log messages

  - by user44725

  So my linux machine keeps crashing, without so much as a bye or a leave. I've tried and tried and failed again to work out whats happening. Any help would be much appreciated. Linux chai 2.6.29.6-0.24.smp.gcc3.4.x86_64 #1 SMP Tue Mar 9 05:06:08 GMT 2010 x86_64 x86_64 x86_64 GNU/Linux Openfiler Here is what the /var/log/messages file says at the time of the latest crash. Nothing that unusual - just greg logging in and out via samba. You'll notice there is a cron running for root every minute - ignore this - this isn't the issue either it was some check I've been doing to discover its problem. Jun 2 10:32:01 chai crond(pam_unix)[16529]: session closed for user root Jun 2 10:32:49 chai samba(pam_unix)[15454]: session opened for user greg by (uid=0) Jun 2 10:33:01 chai crond(pam_unix)[16537]: session opened for user root by (uid=0) Jun 2 10:33:04 chai crond(pam_unix)[16537]: session closed for user root Jun 2 10:41:40 chai syslogd 1.4.1: restart. Jun 2 10:41:43 chai syslog: syslogd startup succeeded That restart was called manually by hand - by clicking the restart button on the box. So basically messages isn't revealing many secrets. dmesg only shows from startup. If there is any output I should paste. Just say when and where and it'll be done. Thanks for your help! Tim

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• Debian - Secure system from current administrator

  - by netadmin

  Hello, I am the Network and Systems Administrator in an organization of just under 500 users. We have a number of Windows Servers, and that is certainly my area of expertise. We also have a very small handful of Debian servers. We are about to terminate the sysadmin of these Debian systems. Short of powering down the systems, I would like to know how I can ensure that the previous admin does not have control of these systems in the future, at least until we hire a replacement linux sysadmin. I have physical/virtual-console access to each of the systems, so I can reboot them in various user-modes. I just don't know what to do. Please assume that I do not currently have root access to all of these systems (an oversight on my part that I now recognize.) I have some experience in Linux, and use it on my desktop on a daily basis, but I must admit that I am a competent user of linux, not a systems admin. I have no fear of the command line however.... Is there a list of steps that one should take to "secure" a system from somebody else? Again, I assure you that this is legit, I am re-taking control of my employer's systems, at the request of my employer. I hope to not have to shut the systems down permanently and still be reasonably certain that they are secure. Thanks for your time.

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• Setting execute permission on a Fedora 11 (host and guest) shared folder file is not working for me.

  - by pmr

  I have set up a VirtualBox Fedora 11 (i386) guest on my Fedora 11 (x86_64) host system with shared folders enabled. I mount the shared folder successfully with the recommended "mount -t vboxsf share /shareddir -o rw,exec,uid=500,gid=100" command. I can successfully read and write files in the share from the guest but I cannot set the execute bit on any file in the share from the guest system. Nothing in GoogleSpace seems to address my issue let alone provide a solution. fwiw, selinux is disabled on both the guest and host and the shared folder is an ext4 file system.

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• Jobs with anacron won't run

  - by mareser

  I would like to run two bash scripts daily using anacron in order to backup some data. Unfortunately I can't figure out why said scripts are not executed. For test purposes I let cron execute the scripts and it worked fine. cat /etc/anacrontab gives # /etc/anacrontab: configuration file for anacron # See anacron(8) and anacrontab(5) for details. SHELL=/bin/sh PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin # These replace cron's entries 1 5 cron.daily nice run-parts --report /etc/cron.daily 7 10 cron.weekly nice run-parts --report /etc/cron.weekly @monthly 15 cron.monthly nice run-parts --report /etc/cron.monthly 1 5 TB_bak /bin/sh /home/vasco2/Dropbox/Scripts/backup_TB.sh 1 5 key_db_bak /bin/sh /home/vasco2/Dropbox/Scripts/bak_key_db.sh The output of ls ~/Dropbox/Scripts/ is backup_TB.sh bak_key_db.sh I use Linux Mint Katya. uname -a gives Linux vasco2 2.6.38-8-generic-pae #42-Ubuntu SMP Mon Apr 11 05:17:09 UTC 2011 i686 i686 i386 GNU/Linux I would be very happy if somebody could point me in the right direction on why those scripts won't get executed. P.S.: There is no anacron tag on superuser.com. Maybe somebody wants to change that.

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• RHEL 5.2 installing on ProLiant BL460c - hangs at 'now booting the kernel'

  - by Dr Rocket Mr Socket

  As the title states, I have a problem. This server and the installation disc are also on the other side of the world to me so... So far, I have tried to start the install with the parameters: linux text noapic noacpi no=apic no=acpi which results in the same hang. I have also disabled a PCI ethernet adapter, I am uneasy about disabling the onboard ethernet adapter I do not know if ILO uses this. Anyone have any advice? Much appreciated. EDIT: full output after trying to begin the installation. boot: linux text Loading initrd.img.................. Loading vmlinuz....... Uncompressing Linux...done. Now booting the kernel stays on this for hours EDIT2: adding the 'mem=40960M' (server has 40 gigs of ram) parameter allows it to proceed but the following output directly after 'Now booting the kernal' Memory: sized by int13 0e801h initrd extends beyond end of memory (0x00ef2090 > 0x00000000) disabling initrd Console: 16 point font, 400 scans Console: colour VGA+ 80x25, 1 virtual console (max 63) pcibios_init : BIOS32 Service Directory Structure at 0x000ffee0 pcibios_init : BIOS32 Service Directory entry at 0xf0000

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• Adding third disk as a single disk in a server with an existing RAID1

  - by slowhandsolo

  I've got a ProLiant DL360 G5 server (Fedora 13) with two SAS disks in a hardware RAID 1, working fine. Now I hot plugged another SAS disk. I'd like to configure this new hard disk out of my RAID, as a single non-RAID disk (ex. /dev/sdb). Even after rebooting the server, I can't see the new disk with "fdisk -l". It displays only my hardware RAID, but not the new disk. [root@myserver]# fdisk -l Disco /dev/cciss/c0d0: 300.0 GB, 299966445568 bytes Disposit. Inicio Comienzo Fin Bloques Id Sistema /dev/cciss/c0d0p1 * 1 126 512000 83 Linux /dev/cciss/c0d0p2 126 71798 292422656 8e Linux LVM Disco /dev/dm-0: 234.9 GB, 234881024000 bytes Disco /dev/dm-1: 10.5 GB, 10536091648 bytes Disco /dev/dm-2: 21.0 GB, 20971520000 bytes Disco /dev/dm-3: 31.5 GB, 31474057216 bytes Disco /dev/dm-4: 1577 MB, 1577058304 bytes However, I can see the new disk using the HP Array Configuration Utility CLI for Linux "hpacucli": [root@myserver]# hpacucli => controller slot=0 physicaldrive all show status physicaldrive 1I:1:1 (port 1I:box 1:bay 1, 300 GB): OK physicaldrive 1I:1:2 (port 1I:box 1:bay 2, 300 GB): OK physicaldrive 1I:1:3 (port 1I:box 1:bay 3, 300 GB): OK => controller slot=0 pd all show detail Smart Array P400i in Slot 0 (Embedded) array A physicaldrive 1I:1:1 Port: 1I Box: 1 Bay: 1 physicaldrive 1I:1:2 Port: 1I Box: 1 Bay: 2 **unassigned** physicaldrive 1I:1:3 Port: 1I Box: 1 Bay: 3 Status: OK Drive Type: **Unassigned Drive** As you can see, I've got two SAS disks in a RAID 1 and the new disk as "unassigned". Is there any way to work with the new disk as another non-RAID single disk? If relevant, I want to create a new partition in my new disk, format it with mkfs and mount it, but as I can't see it with fdisk, I don't know how to do it. Thanks!

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• Linux - real-world hardware RAID controller tuning (scsi and cciss)

  - by ewwhite

  Most of the Linux systems I manage feature hardware RAID controllers (mostly HP Smart Array). They're all running RHEL or CentOS. I'm looking for real-world tunables to help optimize performance for setups that incorporate hardware RAID controllers with SAS disks (Smart Array, Perc, LSI, etc.) and battery-backed or flash-backed cache. Assume RAID 1+0 and multiple spindles (4+ disks). I spend a considerable amount of time tuning Linux network settings for low-latency and financial trading applications. But many of those options are well-documented (changing send/receive buffers, modifying TCP window settings, etc.). What are engineers doing on the storage side? Historically, I've made changes to the I/O scheduling elevator, recently opting for the deadline and noop schedulers to improve performance within my applications. As RHEL versions have progressed, I've also noticed that the compiled-in defaults for SCSI and CCISS block devices have changed as well. This has had an impact on the recommended storage subsystem settings over time. However, it's been awhile since I've seen any clear recommendations. And I know that the OS defaults aren't optimal. For example, it seems that the default read-ahead buffer of 128kb is extremely small for a deployment on server-class hardware. The following articles explore the performance impact of changing read-ahead cache and nr_requests values on the block queues. http://zackreed.me/articles/54-hp-smart-array-p410-controller-tuning http://www.overclock.net/t/515068/tuning-a-hp-smart-array-p400-with-linux-why-tuning-really-matters http://yoshinorimatsunobu.blogspot.com/2009/04/linux-io-scheduler-queue-size-and.html For example, these are suggested changes for an HP Smart Array RAID controller: echo "noop" > /sys/block/cciss\!c0d0/queue/scheduler blockdev --setra 65536 /dev/cciss/c0d0 echo 512 > /sys/block/cciss\!c0d0/queue/nr_requests echo 2048 > /sys/block/cciss\!c0d0/queue/read_ahead_kb What else can be reliably tuned to improve storage performance? I'm specifically looking for sysctl and sysfs options in production scenarios.

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• Intermittent NFS lockups on Isilon cluster

  - by blackbox222

  We have an Isilon cluster with 8 IQ 12000x nodes which exports storage via several NFS shares for a handful of Linux and Solaris clients. There is a Linux system that has one of these NFS filesystems mounted. I/O to this filesystem is moderately heavy from the Linux system. Every 3-4 weeks (it's not on any kind of discernible schedule, and sometimes is more/less frequent than this), we notice that all activity ceases on this NFS mount (the process hangs, as if the network stopped working so process is stuck in uninterruptible sleep) - 30 minutes later, the share recovers and things continue to work normally. The kernel log from the affected machine is as follows: Dec 3 10:07:29 redacted kernel: [8710020.871993] nfs: server nfs-redacted not responding, still trying Dec 3 10:37:17 redacted kernel: [8711805.966130] nfs: server nfs-redacted OK relevant /etc/fstab line: nfs-redacted:/ifs/nfs/export_data/shared/...redacted... /data nfs defaults 0 0 I've checked to see if there are any scheduled processes e.g. cron jobs, Isilon related functions e.g. snapshots, etc that might be causing these hangups but I can't seem to find anything. I'm also not aware of any network related issues or maintenance that would cause this. All of the lockups last almost exactly 30 minutes per the kernel logs. Perhaps someone has some suggestions I could try? (I considered a soft mount to avoid the problems associated with processes accessing the filesystem hanging; however am wary of the corruption that could result and it would not really solve the underlying issue anyway).

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• How to test KVM guest CPU maximum allocation limit?

  - by Ace

  Running Ubuntu 13.04 Host and vm Guest. Using virtio for hdd, nic. Max-allocaion CPU cores is 6, minimum is 2. Ive made a vm with virt-manager just to play with, and to test out kvm. Alright, I have a decent understand how the memory balloon driver works, but I still dont know how to test if the guest OS can utilize the max setting for cpu cores. From what i gather, the host will start one thread of qemu for each core allocated per vm. When i run htop inside the guest, it only shows two cores. (also here is the output of cat /proc/cpuinfo: https://gist.github.com/anonymous/93a361545130923537da ) How can I "force" the guest to allocate the other 4 cores so that it can show 6 cores in htop? Is there a way to do this?

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• How do you passthrough native SATA drives to a guest on ESXi?

  - by John

  I have ESXi 4.0 running on an Intel DX58S0 Mothboardboard with an Intel Core i7 930 processor. VT-d is also enabled. I have three drives in the system, drive 0 is used for ESXi. Drive 1 and 2 contain data from an older machine and show up under the "Storage Adapters" section in configuration. I would like to allow a guest machine to access the data on these drives (as nativly as possible). I have enabled passthrough of the motherboard's built in SATA controller (Intel/Marvell 88SE6121 ). This controller shows up in my guest OS, but the guest shows no drives aside from the normal virtual drive. I have tried a Linux guest and Windows7. I have also configured the host machine to try IDE/RAID/ACHI modes for the SATA controller. Any ideas how I can configure one of my guests to get at the raw data on these drives?

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• What can cause kernel out_of_memory error?

  - by nbolton

  I'm running Debian GNU/Linux 5.0 and I'm experiencing intermittent out_of_memory errors coming from the kernel. The server stops responding to all but pings, and I have to reboot the server. # uname -a Linux xxx 2.6.18-164.9.1.el5xen #1 SMP Tue Dec 15 21:31:37 EST 2009 x86_64 GNU/Linux This seems to be the important bit from /var/log/messages Dec 28 20:16:25 slarti kernel: Call Trace: Dec 28 20:16:25 slarti kernel: [<ffffffff802bedff>] out_of_memory+0x8b/0x203 Dec 28 20:16:25 slarti kernel: [<ffffffff8020f825>] __alloc_pages+0x245/0x2ce Dec 28 20:16:25 slarti kernel: [<ffffffff8021377f>] __do_page_cache_readahead+0xc6/0x1ab Dec 28 20:16:25 slarti kernel: [<ffffffff80214015>] filemap_nopage+0x14c/0x360 Dec 28 20:16:25 slarti kernel: [<ffffffff80208ebc>] __handle_mm_fault+0x443/0x1337 Dec 28 20:16:25 slarti kernel: [<ffffffff8026766a>] do_page_fault+0xf7b/0x12e0 Dec 28 20:16:25 slarti kernel: [<ffffffff8026ef17>] monotonic_clock+0x35/0x7b Dec 28 20:16:25 slarti kernel: [<ffffffff80262da3>] thread_return+0x6c/0x113 Dec 28 20:16:25 slarti kernel: [<ffffffff8021afef>] remove_vma+0x4c/0x53 Dec 28 20:16:25 slarti kernel: [<ffffffff80264901>] _spin_lock_irqsave+0x9/0x14 Dec 28 20:16:25 slarti kernel: [<ffffffff8026082b>] error_exit+0x0/0x6e Full snippet here: http://pastebin.com/a7eWf7VZ I thought that perhaps the server was actually running out of memory (it has 1GB physical memory), but my Cacti memory graph looks OK to me... But strangely the load graph goes through the roof shortly before the kernel crashes: What logs can I look at for more info? Update: Maybe noteworthy - the CPU percentage and network traffic graphs were both normal at the time of the crash. The only abnormality was the average load graph.

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• saving and searching encrypted mail

  - by student

  I often send and receive gpg-encrypted mail. At the moment I use thunderbird + enigmail (in linux) to do that. As far as I know there is no way in thunderbird to find all encrypted messages which bodies contain particular keywords. There also seems to be no option to save encrypted mails decrypted (so they would be searchable). However for me it is important to be able to search old encrypted mails. So my question is: Is there a way in linux to save incoming mails automatically decrypted in my inbox and save outgoing encrypted mail decrypted in the send folder? Both times adding a line to the body which remarks that the mail was encrypted. It could be another email client for linux that could to that or perhaps a solution using procmail or maildrop. For a procmail solution I guess there could be some problems with encoding (perhaps one have to use emil?) the solution should work well with german special characters in subject and body. Note that the solution should work for multipart encrypted messages (including encrypted attachments) too i.e. with everything which could thunderbird + enigmail generate. Further note that I don't want a discussion about security holes. For me it's ok if messages are stored decrypted on my harddrive (which is encrypted as a whole anyway). In doubt for a first solution it would be ok to store my private key passphrase in cleartext on my harddrive, too. The point is that the mails are encrypted on the mailserver or more generally on their "way through the net".

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• SSH Interactive mode not working

  - by Ekin Koc

  I have a Debian based linux server running for a year or so, without any problems. A couple of days ago, ssh interactive mode stopped working for no reason. I mean, I can open an ssh connection just fine, the server greets me with shell but I just can't type anything. However, if I send commands like this: ssh [email protected] cat /var/log/messages, I get the response. I dug through several logs and found one message, which feels remotely relevant to the problem; sh kernel: [10222733.062511] ------------[ cut here ]------------ sh kernel: [10222733.062522] WARNING: at /build/buildd-linux-2.6_2.6.32-39-amd64-7yVIH2/linux-2.6-2.6.32/debian/build/source_amd64_none/drivers/char/tty_ldisc.c:738 tty_ldisc_reinit+0x46/0x7b() sh kernel: [10222733.062526] Hardware name: PowerEdge R210 II sh kernel: [10222733.062528] Modules linked in: ipt_MASQUERADE iptable_nat nf_nat nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 ip_tables x_tables sha1_generic arc4 ecb ppp_mppe ppp_async crc_ccitt ppp_generic slhc loop snd_pcm snd_timer snd soundcore snd_page_alloc i2c_i801 i2c_core pcspkr evdev joydev dcdbas container button processor ext3 jbd mbcache sg sd_mod sr_mod crc_t10dif cdrom usb_storage usbhid hid mpt2sas ahci ehci_hcd libata scsi_transport_sas usbcore bnx2 nls_base scsi_mod fan thermal thermal_sys [last unloaded: scsi_wait_scan] sh kernel: [10222733.062568] Pid: 8662, comm: sshd Not tainted 2.6.32-5-amd64 #1 sh kernel: [10222733.062569] Call Trace: sh kernel: [10222733.062572] [<ffffffff811ff056>] ? tty_ldisc_reinit+0x46/0x7b sh kernel: [10222733.062574] [<ffffffff811ff056>] ? tty_ldisc_reinit+0x46/0x7b Is there any way to get back the sshd working in interactive mode? I tried restarting sshd but that is no help. And somehow, I can not reboot the server. Tried sending shutdown -r now and reboot but it refuses to go down. Should I go ahead and request a physical reboot?

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• Help, my CentOS servers keep going down , No route to host after a random uptime

  - by user249071

  Hello , I have a couple of Centos linux servers, that have a very simple task, they run nginx + fastcgi for php , and some NFS mounts between them, readonly They have some RPC commands to start some downloading processes with wget, nothing fancy , from a main server, but their behavior is very unstable, they simply go down, we tried to monitor ram , processor usage, even network connections, they don't load up so much, max network connections up to... 250 max, 15% processor usage and memory , well, doesn't even fill up, 2.5GB from 8GB max , I have no ideea why can a linux server go down like that, they aren't even public servers, no domain names installed no public serving, for sites. The only thing that I've discovered was that if i didn't restart the network service every couple of hours or so... the servers were becoming very slow, starting apps very slow, but not repoting a high usage of resources...Maybe Centos doesn't free the timeout connections, or something like that...It's based on Red Hat right? I'm not a linux expert , but I'm sure that there are a few guys out there that can easily have an answer to this , or even have some leads to what i can do ... I haven't installed snort, or other things to view if we have some DOS attacks, still the scheduled script that restarts the network each hour should put the system back online, and it doesn't.... Thank you in advance

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