[libvirt-users] how to match the ID of a LUN in a storage pool with the GUID on the target server

[Tom Georgoulias]

On 06/16/2010 01:41 PM, Daniel P. Berrange wrote:
> On Wed, Jun 16, 2010 at 01:20:02PM -0400, Tom Georgoulias wrote:
>> I've configured a libvirt storage pool using an iscsi target from a Sun
>> 7310 storage appliance and am using the LUNs in this target as volumes
>> for my KVM guests.  The setup is very similar to what Daniel covered in
>> a recent blog posting:
>>
>> http://berrange.com/posts/2010/05/05/provisioning-kvm-virtual-machines-on-iscsi-the-hard-way-part-2-of-2/
>>
>> It works great, but I can't figure out how to match the volume names&
>> path IQNs within the storage pool to the GUIDs on the target.
>>
>> For example, here's what I see when I use the vol-info command:
>>
>> # virsh vol-list kvm-target
>> Name                 Path
>> -----------------------------------------
>> 6.0.0.0
>> /dev/disk/by-path/ip-X.X.X.X:3260-iscsi-iqn.1986-03.com.sun:02:<snipped>-lun-0
>> 6.0.0.1
>> /dev/disk/by-path/ip-X.X.X.X:3260-iscsi-iqn.1986-03.com.sun:02:<snipped>-lun-1
>>
>> The IQN matches the targets IQN, but when I browse the LUNs from the
>> storage system I do not see a way to determine which of them is *-lun-0
>> and which is *-lun-1, I only see a GUID and an alias name that I created.
>>
>> Is there any way to get that info (or something else that will do the
>> job) from a virsh command?
>
> Nothing at this time. If you weren't using libvirt, how would you discover
> the GUIDs on the Linux client ? If there is a way to get these from sysfs
> or elsewhere, we can wire it up in libvirt to the<key>  element in the XML
> for the volume. I just don't know how yet...

That's a good question, I tried to figure out a way to do so with 
iscsiadm but didn't find anything.  But I'm glad you mentioned the sysfs 
angle, it prodded me in the right direction and I think I found 
something to work with.

# udevinfo -a -p $(udevinfo -q path -n /dev/sdg)


   looking at device '/block/sdg':
     KERNEL=="sdg"
     SUBSYSTEM=="block"
     SYSFS{stat}=="   20458      183   451623    17494    27820    11891 
  4508156   552205        0    70083   569695"
     SYSFS{size}=="41943040"
     SYSFS{removable}=="0"
     SYSFS{range}=="16"
     SYSFS{dev}=="8:96"

   looking at parent device 
'/devices/platform/host6/session2/target6:0:0/6:0:0:0':
     ID=="6:0:0:0"
     BUS=="scsi"
     DRIVER=="sd"
     SYSFS{ioerr_cnt}=="0x3"
     SYSFS{iodone_cnt}=="0xbcb4"
     SYSFS{iorequest_cnt}=="0xbcb4"
     SYSFS{iocounterbits}=="32"
     SYSFS{timeout}=="60"
     SYSFS{state}=="running"
     SYSFS{rev}=="1.0 "
     SYSFS{model}=="Sun Storage 7310"
     SYSFS{vendor}=="SUN     "
     SYSFS{scsi_level}=="6"
     SYSFS{type}=="0"
     SYSFS{queue_type}=="none"
     SYSFS{queue_depth}=="32"
     SYSFS{device_blocked}=="0"

   looking at parent device '/devices/platform/host6/session2/target6:0:0':
     ID=="target6:0:0"
     BUS==""
     DRIVER==""

   looking at parent device '/devices/platform/host6/session2':
     ID=="session2"
     BUS==""
     DRIVER==""

   looking at parent device '/devices/platform/host6':
     ID=="host6"
     BUS==""
     DRIVER==""

   looking at parent device '/devices/platform':
     ID=="platform"
     BUS==""
     DRIVER==""

# scsi_id -g -x -s /block/sdg
ID_VENDOR=SUN
ID_MODEL=Sun_Storage_7310
ID_REVISION=1.0
ID_SERIAL=3600144f0a523738a00004c18ec990004
ID_TYPE=disk
ID_BUS=scsi


The GUID for this LUN is "600144F0A523738A00004C18EC990004".  That's the 
same number that is used in the ID_SERIAL, except that it has a 3 
prepended on it.  So now I can tell which LUN is really volume 6.0.0.0.

Tom