Red Hat Bugzilla – Bug 479217
Full Virtualized Guest does not see "Virtual Disks" presented to it
Last modified: 2009-12-14 16:26:38 EST
Description of problem: I have a fully-virtualized RH5.3 snapshot6 virtual machine. When I present a "Virtual Disk" to it the presentation portion goes OK, and virt-manager says that the disk has been presented, but when I power up the VM I do not see the presented "Virtual Disk". If I present a disk as a scsi device the Guest does not have a problem detecting it. Version-Release number of selected component (if applicable): RH5.3 RC1 xen Steps to Reproduce: 1. Present a "Virtual Disk" to a fully virtualized RH5.3 guest (I don't know if other exhibit the same behavior.
Do you have the xen-vbd driver loaded in the guest? Without that, the guest will never see the virtual disk. Chris Lalancette
Fixed in 2.6.18-128.
I just tried the same experiment using 2.6.18-128 (RC1) with the same result. However, I noticed that if the VM is running when you add the "Virtual Disk" it does see the device. But then it is lost after you reboot the VM. I do have the xen-vbd driver loaded (version 2.6.18-125). [root@localhost ~]# lsmod | grep xen xen_vbd 49833 0 xen_vnif 58433 0 [permanent] xen_balloon 45641 1 xen_vnif,[permanent] xen_platform_pci 118685 3 xen_vbd,xen_vnif,xen_balloon,[permanent] [root@localhost ~]# modinfo xen_vbd filename: /lib/modules/2.6.18-125.el5/kernel/drivers/xenpv_hvm/blkfront/xen-vbd.ko license: Dual BSD/GPL alias: xen:vbd srcversion: 2DE57D18B4C08FDBDC27998 depends: xen-platform-pci vermagic: 2.6.18-125.el5 SMP mod_unload gcc-4.1
OK, the fact that it gets lost after you reboot the VM is the correct behavior; things you attach on the fly get lost. Only things in the configuration file are persistent. What's the exact command-line you used to attach the disk? Chris Lalancette
Oh, also, please get the xend.log and the output from xm list --long from right before and right after you tried to attach the disk. Thanks, Chris Lalancette
Did you update just the guest kernel? I had the same complaint from our perf team yesterday, made the same recommendation, and the perf team member did a full update of the guest (not just kernel to -128) to -rc1 & that resolved the problem for them. and can you provide a dump of: Provide a dump of ' grep vbd /lib/modules/2.6.18-128.el5/modules.* ' I want to make sure the dependencies are correct. - Don Chris: could he be missing any bug fix to the dom0 tools &/or back-end drivers due to the increased num of vbd patch?
re: comment #3: If you upgraded to -128/rc1, then the xen-vbd modinfo should report version -128, not -125. Therefore, either you didn't boot & test the -128 kernel, or the xen-vbd dependencies are seriously messed up. Please ensure that uname -a reports -128 when you do the modinfo xen-vbd check. *Also*, do a modinfo check on xen-platform-pci; that *must* show -128; the bug fix is in that module. Thanks, Don Dutile
I tried again with RC2. This time I loaded the VM from scratch as apposed to the upgrade and I no longer see the issue. I beleve you were correct in you diagnosis Don. Thanks for your help. Closing the bug -Hector Arteaga