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1608 discussions

Xen vs. iSCSI
by Bill McGonigle 16 Jun '09

16 Jun '09

[previously sent to rhelv5 list, apologies to those on both] I've got a problem I can reproduce easily enough, but really I fail to understand what's going wrong. I've got a 5.3 Dom0, which is running three guests. One is Fedora 10, that runs with local flat files, and works fine. One is Nexenta 2 (opensolaris-based), and that runs off of physical partitions, and seems to work great. The third runs Fedora 11 and and has for its disks, iSCSI devices that are exported from Nexenta (ZFS-backed). I have the Dom0 mapping the two iSCSI devices, one for /boot and one for /. They're showing up initially as /dev/sdc and /dev/sdd. If I go after the iSCSI devices in Dom0, with dd, for instance, they work fine all day. I can read and write the entire devices to and from local files without error. iSCSI seems to work properly in that regard. I'm getting about 38MB/s. I've scrubbed the disk pool and no errors were found and long SMART self-test passed on each of the disks. I've also been able to mount both iSCSI devices and run bonnie++ on them successfully from Dom0. So, I specify those devices in the Xen config for the domU (tried both real device name and /dev/disk/by-path/ names) and the DomU boots and operates as I'd expect. Installation worked fine and typical operations (low volume) work. However, then I try to do something, which I'm assuming is more disk intensive, like running a yum update, and iSCSI seems to fall over. In the DomU, I'll see a lock-up, and then filesystem errors. e.g.: Installing : kernel [############################################ ] 1/33EXT3-fs error (device xvda1) in ext3_ordered_writepage: IO failure In the Dom0, I'll see: sd 6:0:0:0: timing out command, waited 360s sd 6:0:0:0: SCSI error: return code = 0x06050000 end_request: I/O error, dev sdc, sector 37319 sd 7:0:0:0: timing out command, waited 360s sd 7:0:0:0: SCSI error: return code = 0x06000000 end_request: I/O error, dev sdd, sector 29792137 sd 7:0:0:0: timing out command, waited 360s sd 7:0:0:0: SCSI error: return code = 0x06000000 end_request: I/O error, dev sdd, sector 29792313 Both (all) iSCSI devices are failed. Under iostat I see activity to the iSCSI block devices, and the whole machine acts mostly I/O blocked (even the Fedora 10 DomU running on flat files will start throwing nagios into a tizzy). If I do 'service iscsi stop' everything picks right back up (though the DomU using them as its disks is obviously unhappy). When I start iscsi again I can pick right back up (after repairing filesystems in the DomU), and I can repeat the process at will. Sometimes the disks will come back as, e.g. sdd and sde, leaving me to think something still has a handle on sdc. But lsof shows nothing in dom0. One thing that stood out were some of the block and sector number errors being right on power of two boundries: scsi 7:0:0:0: SCSI error: return code = 0x00010000 end_request: I/O error, dev sdd, sector 32768 Buffer I/O error on device sdd, logical block 4096 Buffer I/O error on device sdd, logical block 4097 Buffer I/O error on device sdd, logical block 4098 Buffer I/O error on device sdd, logical block 4099 Buffer I/O error on device sdd, logical block 4100 Buffer I/O error on device sdd, logical block 4101 Buffer I/O error on device sdd, logical block 4102 Buffer I/O error on device sdd, logical block 4103 Buffer I/O error on device sdd, logical block 4104 Buffer I/O error on device sdd, logical block 4105 scsi 7:0:0:0: rejecting I/O to dead device but as I opened with, I'm sort of at as loss as to what is actually causing the problem. Any suggestions for further troubleshooting and/or ideas about what's happening appreciated. Thanks, -Bill -- Bill McGonigle, Owner Work: 603.448.4440 BFC Computing, LLC Home: 603.448.1668 http://www.bfccomputing.com/ Cell: 603.252.2606 Twitter, etc.: bill_mcgonigle Page: 603.442.1833 Email, IM, VOIP: bill(a)bfccomputing.com Blog: http://blog.bfccomputing.com/ VCard: http://bfccomputing.com/vcard/bill.vcf

3 6

Fenker, Oliver is out of the office.
by oliver.fenker＠bayerbbs.com 16 Jun '09

16 Jun '09

Ich werde ab 11.06.2009 nicht im Büro sein. Ich kehre zurück am 29.06.2009. I will be out of the office starting 2009-06-11 and will not return until 2009-06-29

1 0

scripted virt-install fails
by lists＠zfobjects.com 28 May '09

28 May '09

I have successfully installed several CentOS 5 VMs on a CentOS 5 Xen DOM0 using a local repo and kickstart files with Virt Manager. Using the same machine and setup, I have tried a scripted install using same repos and kickstart file with virt-install. The only difference I can see is that with virt-install I'm disabling the display (no VNC). The install goes well but the new VM won't finish booting, it keeps stalling at various things. So far I have disabled smartd and microcode_ctl in kickstart postinstall script, now it is stalling at HAL. Rather than keep disabling services and retrying, I think it's time to ask here what I'm doing wrong ... why does basically the same VM install work with Virt Manager but not with virt-install? Thanks

2 1

KVM and Virt-manager
by Gilberto Nunes 28 May '09

28 May '09

Hi folks... I know, that perhaps this is not the right list for this question, but I need some help... I had install UBuntu with KVM. I deploy some Vm's with virt-manager. Everything works well, but when I use the control panel fro virt-manager, to force shutdown off a machine, some other machine that I do not select, down too... I click with right buttom from my mouse, select the proper machine to force shutdown, but the selected machine and other randon machine folling down together... some trick? thanks -- Gilberto Nunes

1 0

kmod-kvm-2.6.18-92.1.18.el5-72-1.x86_64.rpm outdated, need on for 2.6.18-92.1.22.el5
by Michael Schenck 28 May '09

28 May '09

CentOS Virt, I'm looking for an RPM for the kmod-kvm processor specific modules (kvm-intel or kvm-amd). I've been using L. Farkas's repository, but after the recent kernel updates, I'm out of luck. Best Regards, Michael Schenck

4 7

Re: [CentOS-virt] Bad Disk Performance of domU
by Christopher G. Stach II 26 May '09

26 May '09

----- "Francisco Pérez" <fperez.x(a)gmail.com> wrote: > Thanks all of you. Just with the nonsparse option works all right. > > Then an LVM+nonsparse+phy will be the better setup? > > Regards. Yes, except sparseness is only relevant to file-backed vbds in normal use. (There could ostensibly be a similar lazy block allocation option for a target on something like a SAN/NAS and you would expect some performance degradation for some writes.) -- Christopher G. Stach II

1 0

Re: [CentOS-virt] Bad Disk Performance of domU
by Christopher G. Stach II 26 May '09

26 May '09

----- "Francisco Pérez" <fperez.x(a)gmail.com> wrote: > I guess the bad performance it goes with the writing. For example on > decompression of a big tar.gz, installing rpm packages. Also on > restoring a MySQL Database... > > The first clue when i knew that something were wrong was on the FS > formating stage. It took really long time to format 40 GB to ext3. I > did the same on other machine with a sata disk... surprise! same > software and hardware config except for the inferior disk type and did > it in no time. It sounds like your the virtual disk file is sparse. If that's the case, you traded performance for space. It not only has to deal with the underlying filesystem, but it allocates the space on demand and hits that filesystem's journal. Try an LVM logical disk and see how that performs. -- Christopher G. Stach II

3 4

Profiling tools
by lists＠zfobjects.com 26 May '09

26 May '09

I'm wondering if anyone has suggestions for profiling tools (RAM, CPU, disc IO) suitable for helping estimate the resource requirements of physical machines destined for virtualisation? Preferably open source, and capable of running on Linux or Windows, but anything at all really. I know that CentOS has a suite of "sysstat" utilities and /proc files that can probably provide the answers, I am looking at scripting something up with them if necessary.

2 1

Dynamic XEN USB usage for Win Guest?
by Hildebrand, Nils, 232 26 May '09

26 May '09

Hi, I am trying to attach a Palm Z22 via USB to my fully virtualized Win XP. Dom0-System: CentOS 5.3 x86_64 (Kernel 2.6.18.128.1.10.el5xen) XEN: 3.0.3-80.el5_3.2 XP: 32-Bit Professional lsusb shows: USB Palm: Bus 002 Device 007: ID 0830:0061 Palm, Inc. Lifedrive / Treo 650/680 / Tunsten E2/T5/TX / Zire 21/31/72 / Z22 I found some hints that I have to put usb = 1 and usbdevice = "host:0830:0061" into my DomU-config. When I start the DomU without the device switched on I get (qemu.log): Warning: could not add USB device host:0830:0061 I/O request not ready: 0, ptr: 0, port: 0, data: 0, count: 0, size: 0 I/O request not ready: 0, ptr: 0, port: 0, data: 0, count: 0, size: 0 Triggered log-dirty buffer switch When I start the DomU with the device switched on I don't get this error - but the usb-device does not appear in XP. Questions: - why does the device not appear in XP? - is there a way to dynamically attach the usb-device (it is not present the whole time!)? - in the CentOS documentation abot xen (virtualization guide) I found an option "usbport" but I have found no exaple on how to use it - would this work instead? http://www.centos.org/docs/5/html/5.2/Virtualization/chap-Virtualization -Configuration_files.html search for "usbport". Kind regards Nils

1 0

No cpu throttling for Xeon E5405?
by Dennis J. 23 May '09

23 May '09

Hi, we bought some machines with 2 x quad core Xeon E5405 processors and installed centos 5.3 on them. My problem is that I can't get the cpuspeed service to work. No driver seems to claim responsibility for the throttling and the fallback "modprobe acpi_cpufreq" in the cpuspeed init script just yields a "No such device" message. According to the acpi information the CPUs should support this just fine: cat /proc/acpi/processor/CPU0/info: processor id: 0 acpi id: 0 bus mastering control: yes power management: no throttling control: yes limit interface: yes cat /proc/acpi/processor/CPU0/throttling: state count: 8 active state: T0 states: *T0: 00% T1: 12% T2: 25% T3: 37% T4: 50% T5: 62% T6: 75% T7: 87% At least half of the cores aren't really used at the moment under non-peak load so we are wasting quite a bit of power with this. Any idea on how to get this working? Regards, Dennis

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