vignesh47
1 Copper

VPLEX Batch-migrate pairing tips

Hello All ,

Recently we started off with tech refresh to move away from old CX's. We are using extent migrations for this purpose.

I have noticed that extents do not get paired in order we specify in create-plan, this causes issue;s when you have multiple luns of the same size. check-plan goes well, but random pairing does cause an issue as we are trying to work out scripts for this ( which do not go that well when things get paired randomly and there a huge number of of LUNS to do this via GUI )

A quick example below to elaborate;

  • Lets assume we have 3 x 10 GB luns which we need to migrate
  • batch-migrate create-plan --file server_alpha_to_beta -f A,B,C -t X,Y,Z
  • if we check the file created on management server the pairing is random
  • batch-migrate check-plan - passed. followed by "start"
  • Session summary will show progress.

I would like to avoid editing the file created on management server to get the pairing right.

Is there a way to control source / target pairing in create-plan command ?


Thanks,

Vignesh

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5 Replies

Re: VPLEX Batch-migrate pairing tips

Batch-migrate tool will not create pairing file randomly, it's done based of matching capacities and the device ID's alphabetically. You can always edit file  from vplex management server, i suggest copy the contents to a local editor, make your changes and run the plan-check once more, other than that there is no other way to do it automatically for batch.

vignesh47
1 Copper

Re: VPLEX Batch-migrate pairing tips

Thanks Ayrton,

I understand the logic of matching capacities, but the entire logic of it does not work well if you have lots of ext / devs we need to migrate. so if we had 3 x 10 GB , 3 x 20 GB and 3 x 30 GB contructs we needed to migrate, the auto pairing would go ahead and pick up 20 GB / 30 GB as targets for 10 GB source ( I think it just looks at the basic req of equal or greater ).

Again editing the file seems to be only way, I just wanted to check if someone had come up with these issue's and figured out a smarter way

Cheers !!

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Re: VPLEX Batch-migrate pairing tips

vignesh47

I would't agree with you. When you issue the command to create pairing file, you will specify source devices and target devices, 10GB's will be matched with 10GB's, 20GB's with 20GB's and 30GB's with 30GB's. Yes the targets ID's will be not necessarily as you want it. Easiser way, since you know the source and target pairing you want, i suggest you create a pairing file using a simple shell script which can be used as you batch-plan file, place it in var/log/VPlex/cli and check-plan your plan file and you should be good to go.

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vignesh47
1 Copper

Re: VPLEX Batch-migrate pairing tips

Sorry if you do not agree, try it out if you have a VPLEX - I have documented evidence of multiple test scenario's

Sample msg : ( this is where pairing goes wrong with combining multiple session , as it picks a target which meets equal or larger criteria )

INFO: The target 'xxx' is larger than the source 'yyy'.  Migration to a larger target does not make the additional capacity available for use.  Follow the steps for storage volume expansion to configure the additional capacity.  There may be limitations in some situations; please review VPLEX documentation.  Do you wish to proceed? (Yes/No)

Create plan is not really that useful - the entire reason for starting this thread was to understand if there is a certain pairing logic for that command.

And manually controlling pairing via a file is well understood, that file needs additional inputs apart from just the dev / ext we want to migrate. I wanted to see if there is a way to avoid manually editing the file - obviously from this thread there is no way out

Cheers Aryton !!

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sanman1960
1 Copper

Re: VPLEX Batch-migrate pairing tips

This from the Admin guide:

I think this is what you referred to, as I was looking for the same.

Tom

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