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 Post subject: TDVV2 to TDVV3 migration question
PostPosted: Thu Apr 19, 2018 9:06 am 

Joined: Thu Apr 19, 2018 8:48 am
Posts: 2
Hi. We have recently upgraded our 3PAR 8200 to 3.3.1. We have a relatively simple setup with a single TDVV2 CPG containing 2 volumes that we want to migrate to a newly created TDVV3 CPG. We have followed the guidelines in the HPE document and would just like to confirm with anyone who has already carried out this operation that we aren't missing anything. Before conversion we see the following outputs:

3723264 MiB = Space useage of existing TDVV2 CPG data
2.99 = Dedupe efficiency

5219328 MiB = Free space for conversion

So this looks to us like it will proceed ok as there is enough free space....3.7TB would move into the 5.2TB free space....is that correct? Or does the migration un-dedupe the data first, then dedupe it again in which case the 2.99 multiplier would come into play?

Just as an aside - if for some reason there isn't enough free space for the conversion will the operation simply not proceed?

Thanks in advance for any input - we're just trying to make sure there are no 'gotchas'

Cheers!


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 Post subject: Re: TDVV2 to TDVV3 migration question
PostPosted: Thu Apr 19, 2018 11:51 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 1570
Location: Europe
I haven't done it myself yet, but I've been doing some research.

The first question is how are you planning on doing this? Is your environment Vmware, the very simple solution would be to create new datastores with TDVV3 (maybe hit two birds with one stone and get VMFS6 on those datastores as well if you're thinking vSphere 6.5). Then storage vMotion VMs to the new datastores and delete the old ones.

If you are planning on using DO, I've been recommended is not to go from TDVV2 directly to TDVV3, but to go TDVV2 -> TPVV -> TDVV3. I don't know if that recommendation is still in play, but be worth checking with HPE. When using DO (at least thin -> thin) you need to have enough free space to match the size of the TPVV. So if your volumes are 2x8TB, you would always need 8TB of free capacity to initiate the DO/tune even though you don't need all that space.

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 Post subject: Re: TDVV2 to TDVV3 migration question
PostPosted: Fri Apr 20, 2018 1:31 am 

Joined: Thu Apr 19, 2018 8:48 am
Posts: 2
Thanks for your reply.

The TDVV2 CPG is for our VMware VDI environment but we aren't in a position to recompose VDI pools to TDVV3 CPG volumes due to some of the customisations we have to do on individual machines, otherwise we would use that route.

I will follow up with HPE your suggestion of migrating via a TDDV2 to TPVV to TDDV3 path although I think that would involve us using a tier 1 FC CPG for the TPVV stage.


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 Post subject: Re: TDVV2 to TDVV3 migration question
PostPosted: Mon Apr 23, 2018 4:01 pm 

Joined: Fri Jan 20, 2017 9:39 am
Posts: 58
If you want another data point, I just finished moving from TDVV2 to TDVV3 in a vmware environment. No linked clones but used by a lot of dev/qa people so lots of vms with snapshots. No DO or AO, just plain old VVs

I started with around 43% used space, went up to 63% and then ended about where I started at 43%. I thought I'd end up with more free space compared to when I started but I guess not.

To do the migration I created a couple new CPGs, created new VVs and presented them to the hosts. I went lun by lun (about 20) moving the vms from old lun to new lun and after a bunch of storage vmotions it was all done.

I thought i was going to have to "expand" everything but in the end it was just a simple storage vmotion. My DDS went from about 14TB in 1 CPG down to roughly 4TB spread across two CPGs.


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