Discuss July 2011

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315 participants
287 discussions

HOWTO install CentOS 6 on low memory computer or virtual machine (even 192MB RAM)
by Tomasz Ostrowski 27 Jul '11

27 Jul '11

I've managed to install CentOS 6 on a 192MB virtual machine using LiveCD install-to-disk graphical method. This is not normally possible because of: - hard-coded minimum supported memory in Anaconda installer - it will show a message "You do not have enough RAM to install CentOS Linux on this machine" if you try or force you to use seriously crippled text installer; - a bug in Anaconda installer, which prevents it from using swap during installation. I think it would be useful to be able to install CentOS 6 (or Scientific Linux 6 or RedHat Enterprise Linux - RHEL 6) on low memory old computer or laptop, as it can be very capable firewall, home www server, proxy etc. So the procedure is as follows: 1. Boot to 32-bit CentOS LiveCD (CentOS-6.0-i386-LiveCD.iso) in graphical mode (if you have at least 256MB RAM) or text mode (if you have less than 256MB RAM). 2. Login as root. 3. Edit a file /usr/sbin/anaconda - using vim in text mode or gedit in graphical mode - search for "within" and modify function "within_available_memory" adding a line "return True" like this: def within_available_memory(needed_ram): return True # kernel binary code estimate that is # not reported in MemTotal by /proc/meminfo epsilon = 15360 # 15 MB return needed_ram < (iutil.memInstalled() + epsilon) This would get rid of artificial hard-coded memory requirement. 4. Edit a file /usr/lib/anaconda/storage/__init__.py - search for 4th occurrence of "swapoff" and modify a fragment of function "umountFilesystems" from: for device in devices: if not device.format.mountable and \ (device.format.type != "swap" or swapoff): continue to: for device in devices: if not (device.format.mountable and \ (device.format.type != "swap" or swapoff)): continue (add parentheses - left one after "if not" and right one after "or swapoff"). This would fix a bug in installer. 5. Run "liveinst" which should start graphical installer. 6. During installation create swap partition so that you have at least 1GB of available memory (RAM+swap) (default setup should suffice, but I personally do not recommend it as it used LVM, which AFAIK prevents disks from using barriers). The bug is reported upstream: https://bugzilla.redhat.com/show_bug.cgi?id=708966 but for Fedora Linux. Regards Tometzky -- ...although Eating Honey was a very good thing to do, there was a moment just before you began to eat it which was better than when you were... Winnie the Pooh

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really large file systems with centos
by John R Pierce 27 Jul '11

27 Jul '11

I've been asked for ideas on building a rather large archival storage system for inhouse use, on the order of 100-400TB. Probably using CentOS 6. The existing system this would replace is using Solaris 10 and ZFS, but I want to explore using Linux instead. We have our own tomcat based archiving software that would run on this storage server, along with NFS client and server. Its a write once, read almost never kind of application, storing compressed batches of archive files for a year or two. 400TB written over 2 years translates to about 200TB/year or about 7MB/second average write speed. The very rare and occasional read accesses are done by batches where a client makes a webservice call to get a specific set of files, then they are pushed as a batch to staging storage where the user can then browse them, this can take minutes without any problems. My general idea is a 2U server with 1-4 SAS cards connected to strings of about 48 SATA disks (4 x 12 or 3 x 16), all configured as JBOD, so there would potentially be 48 or 96 or 192 drives on this one server. I'm thinking they should be laid as as 4 or 8 or 16 seperate RAID6 sets of 10 disks each, then use LVM to put those into a larger volume. About 10% of the disks would be reserved as global hot spares. So, my questions... A) Can CentOS 6 handle that many JBOD disks in one system? is my upper size too big and I should plan for 2 or more servers? What happens with the device names when you've gone past /dev/sdz ? B) What is the status of large file system support in CentOS 6? I know XFS is frequently mentioned with such systems, but I/we have zero experience with it, its never been natively supported in EL up to 5, anyways. C) Is GFS suitable for this, or is it strictly for clustered storage systems? D) anything important I've neglected? -- john r pierce N 37, W 122 santa cruz ca mid-left coast

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Error updating CentOS 6 kernel
by Mark 26 Jul '11

26 Jul '11

I finally was able to create a VM in which to load and "play" with CentOS 6, and the first time I went to update the kernel I ran into this: Downloading Packages: kernel-2.6.32-71.29.1.el6.x86_64.rpm | 22 MB 01:11 Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Installing : kernel-2.6.32-71.29.1.el6.x86_64 1/1 grubby fatal error: unable to find a suitable template What does that mean and how do I fix it?

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Gimp PDF plugin - Centos 5
by Frank Cox 26 Jul '11

26 Jul '11

Gimp on Centos 5 has somehow lost its ability to load a pdf file on three (i386) different computers. I'm pretty sure that this used to work. When I try to load a PDF file I get the initial box titled "Load Postscript" with rendering and antialiasing options, but when I hit OK I get an error message: Opening "filename" failed: Plug-In could not open image." Comparing between Centos 5 and Centos 6 I see that I have a file named file-pdf in the gimp plugins directory on Centos 6 x86_64 (/usr/lib64/gimp/2.0/plug-ins) but that file is not preset on the Centos 5 boxes.. -- MELVILLE THEATRE ~ Real D 3D Digital Cinema ~ www.melvilletheatre.com www.creekfm.com - FIFTY THOUSAND WATTS of POW WOW POWER!

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Question about CentOS 6 installation setup
by Mark 26 Jul '11

26 Jul '11

When I created a CentOS VM (using VMWare WorkStation), I installed with the first DVD, and the disk partitioning and installation was all done automatically with almost no input required from me. The problem with this is that the /boot partition was too small (under 50MB) and I couldn't update the kernel (it blew out with a grubby error, which I did not recognize - separate thread on that). Is this a manifestation of using VMWare for the VM platform, or is this "normal" for a 6.0 installation or what? Thanks in advance.

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RADIUS Questions
by Dan 26 Jul '11

26 Jul '11

I've been running FreeRadius 2 on Centos 5.5 for a while now. So far so good. I'm now looking to make connecting to our WPA secured wireless easier. The RADIUS server is running in a VM and since the system is in use I have copied the original and used that copy to create a test environment. I have run through all system updates and have upgraded all relevant packages. The test system is at 5.6 now. Currently with Windows machines I can't just connect to the SSID and enter in a username and password. I have to go and manually add the SSID, modify some settings; specifically turning off validating server certificate, turning off automatically use my Windows login, and turning on User or computer authentication mode. We also have some OS X clients. Fortunately connecting via OS X is easier. The catch is that I have to join the machine to our domain. After that it's pretty much username and password, and they are on. Ideally I would like to have a simple "connect to this SSID, enter your username and password and that's it" solution and still have all requests checked against our Active Directory server. On a side note. I'm going through my settings trying to get this working more smoothly and I ran across: wbinfo --a user%password (yes I'm adding in my username and pass) plaintext password authentication succeeded challenge/response password authentication failed error code was NT_STATUS_ACCESS_DENIED (0xc0000022) error messsage was: winbind client not authorized to use winbindd_pam_auth_crap. Ensure permissions on /var/cache/samba/winbindd_privileged are set correctly. Could not authenticate user MYUSERNAME with challenge/response I know the 2 error lines are permissions related. I'm not sure what the permissions should be on this file/folder. Can someone let me know this? The tutorial from FreeRadius says that I should get output similar to: plaintext password authentication failed error code was NT_STATUS_NO_SUCH_USER (0xc0000064) error message was: No such user Could not authenticate user CHSchwartz%mypassword with plaintext password Yet ntlm_auth --request-nt-key --domain=MYDOMAIN --username=MYUSERNAME NT_STATUS_OK: Success (0x0) So the Auth is working. I don't understand though why my AD server is letting cleartext passwords through. It shouldn't right? Any help would be greatly appreciated. Dan <http://www.liai.org> <http://www.liai.org>

1 0

Upgrading from CentOS 5.6 to 6.0
by Thomas Dukes 26 Jul '11

26 Jul '11

Help! Just ran the installation DVD but there is no option to 'upgrade'. Looked at the RHEL docs, http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Installati on_Guide/ch-guimode-x86.html#id4594292 referenced off the CentOS Release notes but the CentOS installation doesn't offer the 'upgrade'. I use to be able to upgrade by doing a 'yum update'. That doesn't work either. Guess I'm stuck with 5.6 as I an not about to install a new version and have to rebuild all non-rpm packages from scratch. This is worse than Microsoft!!

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centos 6 gdm.custom auto login
by Jerry Geis 26 Jul '11

26 Jul '11

Under centos 5 I modified /etc/gdm/custom.conf to auto login with the following: [daemon] AutomaticLoginEnable=true AutomaticLogin=myuser TimedLoginEnable=true TimedLogin=myuser TimedLoginDelay=0 This doesnt seem to work in Centos 6. What is the new way to accomplish auto login under X11. Thanks, Jerry

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Re: [CentOS] what really starts x11
by Jerry Geis 26 Jul '11

26 Jul '11

lists-centos wrote: > switch inittab to 3. that will get you a line-mode login. after > logging in, issue the command "startx" and debug from there. > > - Richard > > > ------------ Original Message ------------ > >> Date: Monday, July 25, 2011 02:36:02 PM -0400 >> From: Jerry Geis <geisj(a)pagestation.com> >> To: CentOS ML <centos(a)centos.org> >> Subject: [CentOS] what really starts x11 >> >> my inittab file has 5 for starting x on centos 6 >> however x is not starting >> >> what do i look for as why x is not starting ? >> it doesnt even attempt to start that i can tell >> no screen flashing or anything >> >> jerry >> _______________________________________________ >> CentOS mailing list >> CentOS(a)centos.org >> http://lists.centos.org/mailman/listinfo/centos >> > > ------------ End Original Message ------------ > > > > thanks actually i tried that. it does start. it just doesnt start automatically. i can start it manually jerry

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tabs in emacs fundamental mode?
by Devin Reade 26 Jul '11

26 Jul '11

I'm noticing that under CentOS 6, emacs fundamental mode is no longer inserting tabs at factor-of-8 tabstops, but rather is doing some funky guess-the-intended-tab-distance thing like text mode has done for a while, currently using three spaces per tab key. Has anyone tracked down where this was changed and, more to the point, how to get the old CentOS 5 behavior back? FWIW, I'm invoking it as "emacs -nw filename". LANG is "C". Devin -- He is one of those people who would be enormously improved by death. - H. H. Munro

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Discuss July 2011