Legacy HDS Forums

pairresync of a C.O.W snapshot

Discussion created by Legacy HDS Forums on Nov 19, 2007
Latest reply on Jan 8, 2008 by Legacy HDS Forums

Originally posted by: Optic


I have just started to setup C.O.W. snapshots on our NSC55.  I am using the standard paircreate, pairsplit and pairresync commands in CCI.

HORCM configuration files are all setup OK.

After using paircreate to create the C.O.W. snapshot for the first time it works pretty much instantly (which is what you expect, as it doesn't actually have to copy anything unlike a real SI S-VOL).

After executing a pairsplit command to put the pair in PSUS, I am able to mount the S-VOLs as expected (and the C.O.W. pool starts to fill as changes are made to the P-VOL).  This is all working nicely.

The only thing I find a bit strange is the behaviour after executing a pairresync.  This puts the pair into a COPY state.  It can remain in this state for 10-15 minutes before finally changing to PAIR again.

Is this normal?  I would have thought that after executing a pairresync on a C.O.W. snapshot, all that is happening is the snapshot is effectively being deleted from the pool.  There isn't really any copying happening.  I expected this to be an almost instant process.

It isn't really important - I just wanted to make sure this is normal behaviour.  What are other people seeing?