Legacy HDS Forums

BCM YKFREEZE   vs  BCM  SI ATTIME SPLIT

Discussion created by Legacy HDS Forums on Apr 10, 2007
Latest reply on Aug 8, 2007 by Legacy HDS Forums

Originally posted by: mur4790



Hello,

We are in the implemetation phase of creating a 3rd copy (ShadowImage) of our critical Mainframe
volumes.  We were required to install BCM to preserve consistancy.  We use Truecopy/sync to mirror
the volumes to the remote site via DWDM to the R-vols, the TC R-VOLs are also SI  S-VOLS paried up
with the 3rd copy SI TVOLS.

Our goal is to create a 'consistant point in time' of the 3rd copy Shadowimage volumes with minimal or no
host impact or disruption to the TC pairs. We want to execute this daily, we have 1360 volumes.

Up to this point HDS has presented us 2 solutions, to preserve consistancy.

  Option 1   -    setup a consistancy group to the Trucopy Copy group and run a rexx BCM script to basically
  freeze all host I/O to the TC M-VOLs,  suspend TC, Resume TC, quick split the SI copy group.
 
HDS estimated the host impact is somewhere between 20 and 60 seconds, when all I/O from the host to the TC M-VOL may be suspended.  This is a major concern.  Is anyone doing this? if so what is the host impact?


  Option 2  -   is to use the AT-TIME split function against the SI copy group witht the C/T id. We have FICON channels connected to the remote controller and by using the ROUTLIST definition in BCM, appearantly we can accomplish an 'point in time' copy of the SI-TVOLS without doing a freeze to the TC copy groups, eliminating any host impact.

I would be interested if anyone has implemented any one of these options and the impact?              
 
Thanks.

Outcomes