[DRBD-user] primary/primary drbd + md + lvm

Matthew Ingersoll matth at digitalwest.net
Thu Sep 17 19:36:22 CEST 2009

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

I'm testing a 2 node primary/primary drbd setup but had a few concerns  
related to the use of md for raid0 striping.  The setup is as follows:

Each node runs two drbd devices in a primary/primary setup.  These  
devices are then striped using the mdadm utility.  From there, logical  
volumes are setup using LVM (I'm running ais + clvmd to sync the  
nodes).  The following output should explain most of this (identical  
on node00 and node01):

root at node00:~# cat /proc/mdstat
Personalities : [raid0]
md0 : active raid0 drbd1[1] drbd0[0]
       117190272 blocks 64k chunks

root at node00:~# pvs -a
   PV         VG   Fmt  Attr PSize   PFree
   /dev/md0   san0 lvm2 a-   111.76G 31.76G

 From there, logical volumes are created and shared via iscsi.  Doing  
round-robin tests on iscsi has not shown any corruption yet (this  
means i'm reading/writing to both node00 and node01).  My main concern  
is the striping portion and what is actually going on there. I also  
tested the striping using only LVM - this appears to work fine too.

I realize there are a lot of components to this and it may not be  
appropriate for the DRBD mailing list - if so, just tell me to go  
away :)

Any thoughts appreciated!


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