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Re: [CentOS-virt] Shared Storage Options
by Brett Worth 27 Aug '08

27 Aug '08

Jerry Ablan wrote: > Has anyone played with OCFS2? > > http://oss.oracle.com/projects/ocfs2/ Thanks for suggesting this. I've done a fresh install of CentOS 5.2 and put OCFS2 on top. Its really easy to use and install and the the performance looks really good. I'm going to be using OCFS2 for a few more applications from now on. Meanwhile... Once I ran up Xen on these machines I was able to use file based storage allocation to the VMs and have it running with reasonable performance. My original problem is still there however. I've tested the flock functionality of OCFS2 and it works but Xen it seems doesn't do locking even on a shared filesystem. It is possible that Xen is trying to do some other sort of file locking but unfortunately OCFS2 only supports flock. I could write some scripts to replace xm which could check for the existence of a lock file before attempting to start a VM but that seems a bit clunky. Is there a proper way to do this? Regards Brett > -----Original Message----- > From: centos-virt-bounces(a)centos.org [mailto:centos-virt-bounces@centos.org] > On Behalf Of Brett Worth > Sent: Thursday, August 21, 2008 6:22 AM > To: Discussion about the virtualization on CentOS > Subject: [CentOS-virt] Shared Storage Options > > Hello all. > > I would like to canvas some opinions on options for shared storage in a Xen > cluster. So > far I've experimented with using iSCSI and clvm which mixed success. > > The primary concern I have with both of these options is that there seems to > be no obvious > way to ensure exclusive access to the LUN/device to the VM I want to run. > On a couple of > occasions during my playing I've accidentally started the same VM on two > servers and > corrupted the said filesystem. > > I've tried setting up GFS but I don't think I'm smart enough to do that. > The fencing has > me baffled. In fact fencing had me baffled with clvm but I somehow managed > to trick it > into working though probably not how it's supposed to. > > I'd be happy to persist with either of the above methods if I could work out > how to lock > the device. Can anyone offer some advice? > > Regards > Brett Worth

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Installing xen from xen srpm compiled rpms
by Joseph L. Casale 26 Aug '08

26 Aug '08

When I use yum to install xen 3.2.0 and xen-libs it also pulls in then centos kernel-xen? I thought the srpm contained all that was needed besides obvious deps like bridge utils etc? To get this running, I change the grub stanza kernel-xen creates to have the kernel point to xen.gz-3.2 and one of the module lines to point to my custom initrd for pciback loading. That leaves the other module line kernel-xen wrote for vmlinuz-2.6.18-92.1.10.el5xen intact. Why does kernel-xen get pulled in and what's the significance of the vmlinuz line? Thanks! jlc

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VMware Server clock woes (running too fast)
by Michael Ekstrand 25 Aug '08

25 Aug '08

I'm running VMware Server 1.0.6 on a CentOS 5.2 host and am having some clock difficulties. Host OS is x86_64 running on 1.9 GHz AMD Sempron, nVidia chipset. Guest OS's are 32-bit FreeBSD (clock works fine after disabling ACPI, setting the clock source to the PIT, and running the guest tools), WinXP (unknown clock status), and i686 CentOS 5.2 (here is the problem). I've tried pretty much everything to try to fix it. I have host.cpukHz, host.noTSC, and ptsc.noTSC set in /etc/vmware/config. I've booted my kernel with noapic, nosmp, noacpi, divider=10. Sadly, I hit the clocksource=pit with divider bug, so I have not been able to boot with both that and divider=10, although clocksource=pit without a divider also does not work. I even built a custom kernel with SMP and APIC disabled, CPU_HZ=100, and booted with clocksource=pit noacpi, and it also gains time. Could anyone provide a recommendation as to what I can do to fix this problem? -- mouse, n: A device for pointing at the xterm in which you want to type. Confused by the strange files? I cryptographically sign my messages. For more information see <http://www.elehack.net/resources/gpg>.

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Shared Storage Options
by Brett Worth 21 Aug '08

21 Aug '08

Hello all. I would like to canvas some opinions on options for shared storage in a Xen cluster. So far I've experimented with using iSCSI and clvm which mixed success. The primary concern I have with both of these options is that there seems to be no obvious way to ensure exclusive access to the LUN/device to the VM I want to run. On a couple of occasions during my playing I've accidentally started the same VM on two servers and corrupted the said filesystem. I've tried setting up GFS but I don't think I'm smart enough to do that. The fencing has me baffled. In fact fencing had me baffled with clvm but I somehow managed to trick it into working though probably not how it's supposed to. I'd be happy to persist with either of the above methods if I could work out how to lock the device. Can anyone offer some advice? Regards Brett Worth

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Problem with keyboard layout
by Erik Edelmann 20 Aug '08

20 Aug '08

Hi! I'm trying to set up a fully virtualized server using Xen; both host and guest operating system is CentOS-5.2. Otherwise it seems to work fairly well, but I can't get my finnish keyboard work correctly for the guest (when using virt-viewer. No problems on the host). In the beginning, using default settings, the behaviour was as if the keyboard layout had been set to "U.S. English". Trying to set the keyboard layout using administration tools inside the guest had no effect. I also tried vfb = [ "type=vnc,vncunused=1,keymap=fi" ] in the guest config file, and (keymap 'fi') in xend-config.sxp, as suggested by http://wiki.centos.org/TipsAndTricks/Xen, but neither of those had any effect either. Setting keymap = "fi" in the guest config file improved the situation a bit, but there were still a few keys that behaved oddly, e.g. [shift]-[6] gave "K" (should give "&") and ['] gave "b" (should give "'"). I then tried swedish keyboard layout, by setting keymap = "sv" in the guest config file (swedish and finnish keyboards are, I think, the same). That fixed most problems, with only one remaining (as far as I've noticed this far): The [tilde, circumflex, diaeresis]-key won't work. Pressing that key gives nothing, and that key + space gives just space (with and without shift or altgr). Any helpful ideas? Regards, Erik

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Re: [CentOS-virt] iowait / Perfomance problems with xen on drbd (centos 5.2)
by cetertick 18 Aug '08

18 Aug '08

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iowait / Perfomance problems with xen on drbd (centos 5.2)
by Jan Kellermann 18 Aug '08

18 Aug '08

Hi, we have 2 servers on centos5.2 in a cluster with the redhat cman in the configuration SERVER1 > LVM \ CMAN DRBD > XEN SERVER2 > LVM / For each xen we create a new local LVM on each node, put them in a drbd and install an os (debian 4 or ubuntu 8). The xens are running as pvm. Everything works fine since over 4 months now. But we have some performance-Problems: Writing on the Xen-devices produces an iowait about 50 to 60% on the xen-processors. we have 3 szenarios tested: a) Xen on DRBD b) Xen on DRBD but disconnected c) direct mounted DRBD You can see the difference in Write pro Char and Write per Block. a: 3792 / 4011 b: 52037 / 103777 c: 57135 / 325002 See bonnie_result.txt for more data. We attached our drbd.conf and a xen-config for your information. The Server are each 2xDual-Core AMD Opteron(tm) Processor 2214 HE with 32 Gb RAM and 2TB-Harddrive on Raid5 running von CentOS 5.2. The XEN-DomUs are Debian 4 or Ubuntu 8. The NICs are bonded Intel 1GBit. For the DRBD we have an own connection on a seperately subnet. Though we are wondering what there happens. Any Idea? And: YES, we tried a some configurations in the last past months before we are asking you today :) Best regards an Thank you in advance Jan resource server206 { protocol C; handlers { pri-on-incon-degr "echo o > /proc/sysrq-trigger ; halt -f"; pri-lost-after-sb "echo o > /proc/sysrq-trigger ; halt -f"; local-io-error "echo o > /proc/sysrq-trigger ; halt -f"; } startup { degr-wfc-timeout 120; # 2 minutes. wait-after-sb; } disk { on-io-error detach; } net { allow-two-primaries; after-sb-0pri discard-least-changes; after-sb-1pri violently-as0p; after-sb-2pri violently-as0p; rr-conflict violently; max-buffers 16384; max-epoch-size 16384; sndbuf-size 1M; } syncer { rate 100M; al-extents 3313; } on server101.werk21system.de { device /dev/drbd6; disk /dev/xendisk/server206; address 10.20.0.101:7795; meta-disk internal; } on server102.werk21system.de { device /dev/drbd6; disk /dev/xendisk/server206 ; address 10.20.0.102:7795; meta-disk internal; } } ## Ubuntu 64Bit Kernel kernel = '/etc/xen/kernel/vmlinuz-2.6.24-19-xen' ramdisk = '/etc/xen/kernel/initrd.img-2.6.24-19-xen' memory = '1024' root = '/dev/xvda ro' disk = [ 'drbd:server206,xvda,w' ] name = 'server206' vcpus = 2 vif = [ 'ip=X.Y.Z.205,bridge=xenbr0','ip=10.10.10.205,bridge=xenbr1' ] vfb = [ 'type=vnc,vncunused=1,keymap=de' ] keymap = 'de' on_poweroff = 'destroy' on_reboot = 'restart' on_crash = 'restart' ================================================================================= XEN ON DRBD CONNECTED Version 1.03b ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP ubuntu64 2G 3792 6 4011 0 3170 0 33006 40 182491 6 231.1 0 ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ ================================================================================= XEN ON DRBD DISCONNECTED Version 1.03b ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP ubuntu64 2G 52037 85 103777 26 43139 5 33510 41 174650 5 212.8 0 ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ ubuntu64,2G,52037,85,103777,26,43139,5,33510,41,174650,5,212.8,0,16,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++ ================================================================================= DRBD CONNECTED W/O XEN Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP server101 2G 57135 97 325002 94 16498 3 61150 94 1166962 100 +++++ +++ ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ server101,2G,57135,97,325002,94,16498,3,61150,94,1166962,100,+++++,+++,16,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++

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can cron.daily crash my dom0s?
by Heiko 18 Aug '08

18 Aug '08

Hello, I have 2 servers which share 2 partitions with drbd, on each machine runs one VM on the drbd device, so that I have primary/secondary and secondary/primary drbd devices. There are also some more XEN VM´s that only do aa mysql replication and one is standalone. In the last 4 weeks I had 2 incidents where both machines did a sudden reboot, first one machine and 2 minutes later the other one. I cant find anything in the logfiles, only that a few seconds before the secondary drbd device got a timeout (Aug 18 04:02:14 xen-A1 kernel: drbd1: PingAck did not arrive in time.) the cron.daily started: Aug 18 04:02:01 xen-B1 crond[25033]: (root) CMD (run-parts /etc/cron.daily) Aug 18 04:02:01 xen-B1 anacron[25037]: Updated timestamp for job `cron.daily' to 2008-08-18 Aug 18 04:06:06 xen-B1 crond[2963]: (CRON) STARTUP (V5.0) the last line seems to be the reboot. here the content of my cron.daily folder. [root@xen-B1.blab:/etc/cron.daily]# ls 0anacron 0logwatch cups logrotate makewhatis.cron mlocate.cron prelink rpm tmpwatch I had also heartbeat running on the machines, after the last crash I thougt it was heartbeat that rebooted the machines, so I disabled it, but now I see it isnt heartbeat that causes these reboots. I use centos 5.1 with no selfcompiled packages. Why are my machines doing this, and how to fix this? greetings and thanks Rupert

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Cannot start xen domUs anymore, domUs hang on kernel startup, happens after a long dom0 uptime
by Pasi Kärkkäinen 14 Aug '08

14 Aug '08

Hello! I've noticed this problem two times now.. last time I fixed it by rebooting the (centos 5.1 x86 32b) xen host/dom0. Symptoms: - Already running domUs (debian 2.6.18-6-xen-686 32b PAE) continue running and working OK - Cannot start new domUs (debian 2.6.18-6-xen-686).. kernel bootup just hangs before running initrd. Same domU with the exact same xen domU cfgfile worked earlier. - This problem starts to happen after a "longer" uptime.. atm uptime for the dom0-host is 174 days. Cannot say what the actual "limit" is.. last time I used the dom0 everything worked fine, now it doesn't.. "xm list" shows the domain as "-b----" and the Time(s) for the domain does not increase.. it stays at 1.9 or so. It might increase to 2.0 after 15 mins or so.. it looks like nothing happens in domU kernel. "xm console" shows the bootup has stalled.. destroying the domU and restarting it might show the hang in a bit different place (+- a couple of lines). It always hangs before actually executing initrd image. Example console output: checking if image is initramfs... it is Freeing initrd memory: 12028k freed Grant table initialized NET: Registered protocol family 16 SMP alternatives: switching to SMP code <hangs here, nothing happens anymore> Like said, it could be a couple of lines later or earlier where it hangs.. I tried changing the domU to use just a single vcpu.. doesn't help. I tried changing (lowering and increasing) the amount of memory.. didn't help either. Any ideas how to debug this? -- Pasi

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Check out Proxmox VE... can CentOS improve on this?
by Scott Dowdle 13 Aug '08

13 Aug '08

Greetings, I'm a big OpenVZ fanboy. I've sent a few emails on this list that proves that... and I'm sure I've annoyed some people... but be that as it may... I would like to draw everyone on this list's attention to Proxmox VE. What is Proxmox VE? Here's a review from the end of June: ProxMox: The high-performance virtualization server for the rest of us http://blogs.zdnet.com/BTL/?p=9181 It is a "bare-metal" Linux distribution based on Debian that has been stripped down to a minimum that includes a kernel that provides support for both KVM and OpenVZ so it does fully virtualized machines (requiring hardware support in the CPU) and containers. It has a nice web-based management system that is fairly feature complete and allows for the easy creation and management of KVM virtual machines and OpenVZ containers. It also has clustering features. That's a long enough description. Ok, how does this differ from everything else out there? 1) It is bare-metal... just pop in the CD (which is a 250MB download)... boot up the machine, answer about two questions... a few minutes worth of install time... and a reboot later... you have what looks very similar to a VMware ESX host... with a console (text) login screen that says... I man a Proxmox VE machine... connect to me at the following URL. Start browsing. 2) It supports both fully virtualized machines AND containers 3) It has a really nice, maturing (two releases so far) web-interface for managing everything 4) It is cluster aware - add additional Proxmox VE machines, use the really simple command line program to make each machine aware of all of the others... and bang the web-interface on any machine sees all of the virtual machines on all nodes 5) The web-interface includes VNC-java-applet based access so you can graphically attach to any virtual machine including the console of an OpenVZ container. For KVM machines, you get to see the BIOS / boot from ISO image before virtual machine is even on the network 6) Proxmox VE shows the potential that exists with a FOSS OS, FOSS Virtualization products... in a completely FOSS product... that is freaking easy to install, setup and use... that works well Problems - Some of the features aren't done yet. Proxmox VE is a little ahead of its time. Live migration doesn't quite work for OpenVZ yet (although it works fine in stock OpenVZ with their stable kernel branches). Proxmox VE is still in beta. Basically, if and when the Proxmox VE concept is fully realized and matured it'll be a killer app that makes business folks go... Linux DUH... for those that care about virtualization... like yoous guyyys on this hea list. Ok... so any chance CentOS or some of the members of the CentOS development community would like to borrow the Proxmox VE idea (perhaps even their web-interface code) and make something like Proxmox VE... but based on CentOS... that supports Xen and OpenVZ? It would have the benefit of being able to run on both systems with and without hardware support for Virtualization - if you have VT you can run fully virtualized Xen AND para-virtualized machines... if not... para-virtualized VMs only... and in both cases OpenVZ containers. The form-factor would have to retain all of the properties I mentioned above... I think... for it to be a huge success. Where to start? Get two machines to test on... desktops are fine as long as they have VT in the CPU. Download the 250MB Proxmox VE iso. Burn disc. Boot disk. Answer two questions. Wait 5 minutes. Reboot. Play with it. See what you think... and use your imagination. If impressed, plan the take over of the world with a similar setup based on CentOS. Then when RHEL6 comes out and KVM is here... switch to KVM. BTW, the OpenVZ Project had a kernel package built on the RHEL kernel that included both Xen and OpenVZ but I can't seem to find it now. Notice I'm not providing any links to Proxmox VE. You have to care enough to google for it. :) TYL, -- Scott Dowdle 704 Church Street Belgrade, MT 59714 (406)388-0827 [home] (406)994-3931 [work]

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