BCV restore to alternate STD

Question

Hello Everyone,

I need to restore BCV data to an alternate STD. I have done this before using the symmir -sid sid id -f filename.txt restore -full and it works fine.

My question is that after the full restores were complete to the alternate STD and were split, I then needed the BCV's to be associated back with their original STD's again. With my limited experience, I went back and ran a full establish to the original STD's which worked fine, but was very time consuming.

I have seen the 'associate' command (never used it) and was wondering if this would work instead? Could I somehow reassociate the BCV back to it's original STD and then on next establish, it would just perform it's normal incremental establish?

Thanks in advance!!

dynamox · Accepted Answer

yeah, and the reason i think it did not work is because when you restored from BCV to your secondary STD ..it formed a new relationship between that STD and BCV hence destroying session between the original STD and BCV.

Darrell-uVlTI · Answer

Sorry, but I think I'm looking for a single BCV to multiple STDs (?)
I believe after I split the BCV from the second STD, the normal establish back to the original STD did not work and I had to perform a -full.

Darrell-uVlTI · Answer

Agreed. So, do I have to perform a -full to the original STD or can I somehow re-associate them in a different way so I don't have to perform the full to get the relationship re-created?

Message was edited by:
Darrell

dynamox · Answer

you could just done a regular established and it still would do an incremental sync as STD maintains sessions to multiple BCVs ..i don't remember how many ..i think around 16.

dynamox · Answer

actually ..i am wrong ..this is what TimeFinder doc says:

Establishing multiple BCVs with a single standard device
 
You can fully establish (at different times) up to eight BCV devices associated with a
single standard device. The BCV devices must also be associated to the same device
group.
Note: Using the environment variable SYMCLI_MAX_BCV_PAIRS, the maximum number of
pairs (established or restored) can be adjusted between 1 to 16 BCV devices.
With this feature, standard devices retain a relationship with multiple BCVs as long
as those BCVs do not become paired with another standard.

dynamox · Answer

i am looking at TimeFinder doc and can't find anything that says you can do that. STD device can be associated to multiple BCVs, but a BCV can only be associated to one STD. I would try the attach command:
"symmir -g prod attach DEV001 BCV ld BCV001" and then establish it "symmir -g ProdBgrp -full establish DEV001 BCV ld BCV001 -noprompt"
..but i doubt it would work ..worth a shot.

Darrell-uVlTI · Answer

At that point, you are still performing a full establish, right? (In the second command I see the -full switch)

If that's the only option I have, then that will have to do. After further research, the 'associate' option I was mentioning was for symbcv which isn't what is needed here....

How about running a normal establish with the -force option?

dynamox · Answer

yeah ..can you try just a regular establish ?

Client321 · Answer

use symclone instead of symmir

dynamox · Answer

thats a pretty good suggestion..you could clone from bcv to another standard device ..the only caviat i see is that your BCV can not be raid-5 ..it has to be either unprotected bcv or 2 way mirrir bcv and it has to be in split state before you initiate symclone session. I would also find out what state your clone session needs to be before you re-establish your bcv.

Darrell-uVlTI · Answer

I finally broke down and opened a ticket. Dynamox was correct - when I restored to the alternate STD, the track information that the original STD had with the BCV was destroyed. The only way to get it back is with the -full option.

As an aside - this was my first post and I wanted to let you know that it was very, very helpful and you guys are very quick to respond. Thanks again for your input - You guys ROCK!!

xe2sdc · Answer

Dynamox I do not agree with you .. You can use symclone to copy data from ANY device to ANY other device, given that both have the same "geometry" (size of volume + number of members and striping if it's a meta). You can even have RAID5-BCV devices that you use with symmir to produce the first copy and any other device as the clone-target (given the above limitation).

Your suggestion is better then what you think

Cloning the BCV to the "alternate" STD seems to me the best choice since will leave the "incremental" relationship between the first STD and it's BCV while giving you the chance to push the data from the BCV to a different STD when needed.

dynamox · Answer

ok ..maybe i don't undersand this statement from TimeFinder doc:Note: You cannot create a copy session between a BCV device and a target device if the BCV isin clone emulation mode.

dynamox · Answer

Stefano,looks like i read it correctly ..you can not use RAID-5 BCV that has been established to a STD as a clone source. I just converted a RAID-5 STD to a BCV+R-5, then i established it to a STD, split it ..and then i tried to use this BCV as my clone source ...and this is what i got:$ symclone -g testvg create -copy -diff BCV001 sym ld CLN001 Execute 'Create' operation for device 'BCV001' in device group 'testvg' (y/) ? y 'Create' operation execution is in progress for device 'BCV001' paired with target device 'CLN001' in device group 'testvg'. Please wait... The BCV device cannot be manipulated because it is BCV attached to a STD device

xe2sdc · Answer

Woops ... so with raid5-bcv you need to cancel the relationship between STD and BCV before cloning and later go with a full establish between the STD and its BCV. Sorry !

Symmetrix

BCV restore to alternate STD

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