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July 10th, 2009 10:00

DR testing - fracture question

Running MirrorView/A on a pair of CX3-20s (1 at each site, site A is primary and site B is secondary)

We are looking to do some DR testing, during which we will promote the secondary copies, perform some testing and then flip back after the testing. We do *not* want to retain any of the data/changes that occur during the test on site B. Here is my plan so far:

1. synch site A to site B
2. fracture site B
3. promote site B

4. (mount LUNs and perform testing at site B which writes to LUNS)

5. promote site A
6. synch site A to site B

but I am not sure if I will be able to promote site B in step 3, since it will be fractured. I could do it this way:

1. synch site A to site B
2. promote site B
3. fracture site A

4. (do testing)

5. promote site A
6. synch site A to site B

But then I am in the same situation in step 5...I guess my basic question is can I promote a fractured mirror, and if not, any suggestions on what the "right" way to do this is?

Thanks....

15 Posts

July 11th, 2009 02:00

In terms of fracture, there are admin fractures (deliberate) and system fractures (loss of communication). You can promote an admin fractured LUN.
Bear though, that you should unmount the former Primary mirror first. Otherwise any writes to this LUN, which is now the Secondary, will make the mirror inconsistent and therefore would require a full sync to put right. If you have to mount a secondary, take a snap or clone of it, then mount this instead.

3 Posts

July 13th, 2009 09:00

Yes - the intention is to throw out any changes (writes to the DB) made during the DR testing at the secondary site and then flip back to primary with the data that was present prior to the testing (admin fracture the mirrors so that the changes made are not replicated back to the primary site during the testing)

the planned steps would be:

unmount primary LUNs from servers
sync primary -> secondary
admin fracture secondary
promote secondary
mount secondary LUNs at DR site and perform tests
umount secondary LUNs at DR site
promote primary LUNs
re-sync primary to secondary (this will overwrite any changes made to the secondary LUN during testing)

using a snapshot would probably be better - do I need additional SW packages/licenses to use snapshots?

Thanks...

3 Posts

July 31st, 2009 13:00

Just to provide closure...this worked:

* unmount LUNs at prod site
* sync secondary
* promote secondary to primary
* fracture secondary (old primary)
* mount LUNs at DR site and perform tests
* unmount LUNs at DR site
* promote secondary (old primary) to primary (throws warning about becoming out-of-sync, choose "force promote"
* sync secondary (this is a full sync and may take hours/days to finish depending on your environment)
* mount LUNs at prod site (sync still running in background)

will definitely be looking into getting SnapView as that would be a much less risky/complicated way to do the DR testing.

15 Posts

August 1st, 2009 01:00

Sorry, missed your previous question. Yes, using SnapView clones for this would definately be a good move, if you do not need to have your mirrors remote.
You will need the SnapView enabler for this though.
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