[CentOS-virt] KVM, virsh attach-disk problems

Sun Apr 24 05:55:08 UTC 2011
Jussi Hirvi <listmember at greenspot.fi>

Maybe my question is difficult, though it should not be. "Virsh 
attach-disk" seems to be poorly documented.

One correction: this was definitely not "my last problem" - it was only 
the latest. :-)

Now I continue configuring my kvm system with the "traditional" way - 
one filesystem per guest.

- Jussi

On 23.4.2011 17.58, Jussi Hirvi wrote:
> Greetings, list!
>
> I hope you forgive cross-posting - I only now found this list.
>
> I am in the process of configuring a KVM stack of about 8 vms. Mostly I
> am concerned about performance, as there will be a lot of I/O.
>
> My last problem is this: I try to add a fresh, unformatted disk
> partition to a KVM guest. I follow the directions given here:
>
> http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html-single/Virtualization/index.html#proc-Virtualization-Adding_storage_devices_to_guests-Adding_physical_block_devices_to_virtualized_guests
>
> First I check that the module acpiphp is present on the guest. It is.
>
> On the host I write:
>
> virsh attach-disk test1 /dev/sdb1 sda --driver tap --mode shareable
>
> - test1 is my guest domain
> - /dev/sdb1 is the name of the unformatted partition on the host
> - sda is what it is supposed to be called on the guest (the name is
> unused on the guest)
> - the example in RHEL Virtualization guide says "--mode readonly". This
> does not sound right for a hard disk; hence I try "--mode shareable";
> the error (see below) however is the same, whichever I use
>
> Now, the command above produces this error. I find no google results
> with this error text. Can someone tell, what causes the error?
>
>   >  >  error: Failed to attach disk error: operation failed: adding scsi
>   >  >  disk controller failed: type scsi not a hotpluggable PCI device.
>   >  >  failed to add if=scsi
>
> I found a post (2009, on fedora-virt list), which is relevant:
>
> http://www.redhat.com/archives/fedora-virt/2009-December/msg00032.html
>
> Otherwise, I have found almost nothing!
>
> BTW, I can attach a disk to the KVM guest, using a virtio driver:
>
>   >  >  [root at 113 info]# virsh attach-disk test1 /dev/sdd1 vdb
>   >  >  --driver virtio --mode shareable
>    >  Disk attached successfully
>
> I have not seen any mention anywhere about using virtio drivers like
> this. And the problem with this is that the new disk does not survive
> guest reboot. At guest startup virsh complains about the virtio drivers.
>
> - Jussi
>


-- 
Jussi Hirvi * Green Spot
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Tel. +358 9 493 981 * Mobile +358 40 771 2098 (only sms)
jussi.hirvi at greenspot.fi * http://www.greenspot.fi