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 Post subject: 3.3.1MU3 - migrating VVols to get new features
PostPosted: Thu Jul 11, 2019 4:20 am 

Joined: Wed Mar 12, 2014 11:27 am
Posts: 9
Hi all,

simple enough question. Customer 3PAR (8200) with light workload. Customer has a mix of thin and thin-dedup vols currently deployed from a raid 6 CPG built when the array was at 3.2.2 code.

Customer would like to leverage better space savings using dedupe and compression where appropriate.

My understanding would be that in order to leverage latest dedupe capabilities in 3.3.1 they'd need to first convert any dedup vols back to thin. Then from there back to dedup but into a CPG created under 3.3.1

something akin to

tunevv usr_cpg OLD_CPG –tpvv MY_VOLUME

tunevv usr_cpg NEW_CPG –dedupe MY_VOLUME

and I guess the same would also be need for any copy space.

Assume if they wanted to leverage dedupe and compression on a vol it would be

tunevv usr_cpg NEW_CPG –dedupe -compr MY_VOLUME
(after first converting it to a tpvv if needed)

Hopefully my thinking is on the right lines but any advice appreciated.

The customer currently leverages dedupe vols in their Citrix environment which provides great savings so I guess doing this process over under 3.3.1 can generally only improve things.

They are also asking about adding compression into the mix to make even more savings on space. I'm aware that the 8200 is generally not considered to be powerful enough to cope with heavy compressed volume workloads but as the customer footprint from a workload perspective is light I suspect it would be probably be ok in this case.

Are there specific cases were compression and dedupe combined would not be recommended or is it simply a matter of ensuring that whatever choices are made they do not push the CPU utilisation beyond a reasonable point and thus impact performance.

Any advice or best practice to follow much appreciated.

thanks

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 Post subject: Re: 3.3.1MU3 - migrating VVols to get new features
PostPosted: Thu Jul 11, 2019 6:39 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 957
Location: Europe
Something to keep in the back of your mind.

When using compression you both compress on write and uncompress at read. Most other features related to storage only has a "penalty" on write. If you get into resource issues with compression it could get painful.

I would use the checkvv in CLI when upgraded to 3.3.1 to see if there is any real gain with compression.

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 Post subject: Re: 3.3.1MU3 - migrating VVols to get new features
PostPosted: Thu Jul 11, 2019 8:45 pm 

Joined: Tue Mar 29, 2016 9:32 pm
Posts: 108
I'd say just the usual common sense stuff, if you know the data to go on the volumes is already compressed or not suitable for compression then don't use compression on the array.
The 8200/8400s are a bit weedy for compression, light use would be OK though.

In regards to moving to a new version dedupe store, skip the step to thining the volumes to the old CPG, just run the second command and tune them to the new CPG and convert with -dedupe.

Move a few volumes then run compactcpg on the old CPG to get some space back, rinse and repeat.


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 Post subject: Re: 3.3.1MU3 - migrating VVols to get new features
PostPosted: Fri Jul 12, 2019 4:12 am 

Joined: Wed Mar 12, 2014 11:27 am
Posts: 9
markinnz wrote:
I'd say just the usual common sense stuff, if you know the data to go on the volumes is already compressed or not suitable for compression then don't use compression on the array.
The 8200/8400s are a bit weedy for compression, light use would be OK though.

In regards to moving to a new version dedupe store, skip the step to thining the volumes to the old CPG, just run the second command and tune them to the new CPG and convert with -dedupe.

Move a few volumes then run compactcpg on the old CPG to get some space back, rinse and repeat.


thanks for that. Would that apply even if the volume is already de-duped?

so i can run

tunevv usr_cpg NEW_CPG –dedupe MY_VOLUME

on an existing dedupe volume as well as any existing tpvv created under 3.2.2?

thanks
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 Post subject: Re: 3.3.1MU3 - migrating VVols to get new features
PostPosted: Mon Jul 15, 2019 1:13 am 

Joined: Tue Mar 29, 2016 9:32 pm
Posts: 108
If the volume is already a dedupe volume then just drop the "-dedupe" option to move it to the new CPG, if it's the first dedupe volume to move to the new CPG it'll probably have poor compaction ratio but as more volumes and data gets added it'll improve.
Volumes that aren;t dedupe already and you want to dedupe then add the option to the tunevv command.


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