libvirt users - Aug 2011 - which vols added to storage pool during refresh?

(opps, actually meant to post this to libvirt-users instead of 
libvirt-cim...)


We're looking at a problem when we have a libvirt pool defined, below 

[root at xnl2192 ~]# virsh pool-dumpxml ScsiPool-host2 
<pool type='scsi'> 
  <name>ScsiPool-host2</name> 
  <uuid>f2ea1882-881f-9f49-838d-39e070f68002</uuid> 
  <capacity>136583315456</capacity> 
  <allocation>136583315456</allocation> 
  <available>0</available> 
  <source> 
    <adapter name='host2'/> 
  </source> 
  <target> 
    <path>/dev/disk/by-id</path> 
    <permissions> 
      <mode>0700</mode> 
      <owner>-1</owner> 
      <group>-1</group> 
    </permissions> 
  </target> 
</pool> 

As you can see, this pool maps to /dev/disk/by-id. There may be a large 
number of actual volume entries in /dev/disk/by-id, however it appears 
only a distinct subset of them are actually added into the libvirt pool 
when you do a pool-refresh. What does libvirt check when determining 
which, and whether or not, to add one of these volume into the vol-list? 

In particular, we have a case when one specific volume in /dev/disk/by-id 
is *not* added into the pool, and no amount of pool-refresh makes a 
difference. We did notice that if you remove all the sym links in 
/dev/disk/by-id and do a pool-refresh, that libvirt re-scans the bus, 
recreates the links in /dev/disk/by-id, and adds (some of) the volumes 
back into the vol-list. But not this one problematic vol, so clearly there 
is something about this vol that libvirt doesnt like and why it is 
(deliberately?) not added to the pool. 

What checks, etc does libvirt make against vols when determining whether 
to add them to a pool? 

- G 

Dr. Gareth S. Bestor
IBM Senior Software Engineer
Systems & Technology Group - Systems Management Standards
971-285-6375 (mobile)
bestor at us.ibm.com_______________________________________________
Libvirt-cim mailing list
Libvirt-cim at redhat.com
https://www.redhat.com/mailman/listinfo/libvirt-cim
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On Wed, Aug 17, 2011 at 10:36:26AM -0700, Gareth S Bestor
wrote:
> As you can see, this pool maps to /dev/disk/by-id. There may be a large 
> number of actual volume entries in /dev/disk/by-id, however it appears 
> only a distinct subset of them are actually added into the libvirt pool 
> when you do a pool-refresh. What does libvirt check when determining 
> which, and whether or not, to add one of these volume into the vol-list? 
> 
> In particular, we have a case when one specific volume in /dev/disk/by-id 
> is *not* added into the pool, and no amount of pool-refresh makes a 
> difference. We did notice that if you remove all the sym links in 
> /dev/disk/by-id and do a pool-refresh, that libvirt re-scans the bus, 
> recreates the links in /dev/disk/by-id, and adds (some of) the volumes 
> back into the vol-list. But not this one problematic vol, so clearly there 
> is something about this vol that libvirt doesnt like and why it is 
> (deliberately?) not added to the pool. 
> 
> What checks, etc does libvirt make against vols when determining whether 
> to add them to a pool? 
If we have an error processing any volume, that will be skipped. There
is one non-error related check though, that may cause a volume to be
skipped:

    /* We don't create volumes for devices other than disk and cdrom
     * devices, but finding a device that isn't one of those types
     * isn't an error, either. */
    if (!(device_type == VIR_STORAGE_DEVICE_TYPE_DISK ||
          device_type == VIR_STORAGE_DEVICE_TYPE_ROM))
    {
        retval = 0;
        goto out;
    }

What value is in 

   /sys/bus/scsi/devices/XXXXX/type

for the LUN in question ?  And is that value different for all the
other LUNs in that HBA ?


Daniel
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