PVG-strict/partially-distributed Policy?

[rveri-admin]

Hi Experts,

I came acros something PVG-strict/partially-distributed,  policy type of LV,

What is this type of plocy means.  Why it is partial distributed.  

$ lvdisplay /dev/vgCMEXE002/lvodb
--- Logical volumes ---
LV Name                     /dev/vgCMEXE002/lvodb
VG Name                     /dev/vgCMEXE002
LV Permission               read/write
LV Status                   available/syncd
Mirror copies               0
Consistency Recovery        MWC
Schedule                    parallel
LV Size (Mbytes)            245696
Current LE                  15356
Allocated PE                15356
Stripes                     0
Stripe Size (Kbytes)        0
Bad block                   on
Allocation                  PVG-strict/partially-distributed
IO Timeout (Seconds)        default

Any more information will be helpful,

Thank You.. 

[Torsten.]

Please post

# vgdisplay -v vgCMEXE002

# lvdisplay /dev/vgCMEXE002/lvodb |head -n 30

[rveri-admin]

Hi Torsten,

Please find the output , ..  

If there anything wrong or is it configured that way.  How is the distribution happening. Why shows partital.  Thank you.

[Torsten.]

The PVG does not make sense here, because you don't have a mirror, but it does not harm in any way.

Here is the distribution:

You can see it is really "partial". I assume it is on SAN. Could you tell more details?

   --- Distribution of logical volume ---
   PV Name                 LE on PV  PE on PV  
   /dev/disk/disk4838      6399      6399      
   /dev/disk/disk4835      5118      5118      
   /dev/disk/disk4833      3839      3839      

[P Arumugavel]

Here the PVG-strict doesn't seem to be for a valid reason as you dont use any mirror.

PVG_strict -- Mirror copies are not allowed to sit on the same physical volume group.

Distributed/partially-distributed  --> Only one free extent is allocated from the first available physical volume.  The next free extent is allocated from the next available physical volume.  Allocation of free extents proceeds in round-robin order on the list of available physical volumes.

Difference:

Distributed --> Two consecutive logical extents are guaranteed to be located on different physical volumes.

Partially-distributed --> Two consecutive logical extents are NOT guaranteed to be located on different physical volumes.

 00006 /dev/disk/disk4838      00002 current  
 00007 /dev/disk/disk4838      00005 current

...

...

00011 /dev/disk/disk4838      00009 current  
00012 /dev/disk/disk4838      00004 current 

Rgds...