sreejith1986
Contributor
Contributor

vSAN deduplication and compression shows no savings

The VMs in our environment  are encrypted at the OS level . Does this oppose Dedupe & compression to work in VSAN?

The benefits of dedupe and compression are nil and can also be seen as such in the utilisation charts.

if not possible, Is it worth then to disable compression & de dupe considering the overhead de dupe & compression has?

Regards,

Sreejith

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4 Replies
TheBobkin
VMware Employee
VMware Employee

Hello sreejith1986​,

"The VMs in our environment  are encrypted at the OS level . Does this oppose Dedupe & compression to work in VSAN?"

Do you mean something other than vSAN encryption or VMware VM encryption? These work with Dedupe but I wouldn't be sure aside from these, though in theory I would imagine they do as a block is a block is a block and if it has the same data then it *should* be able to dedupe it.

"The benefits of dedupe and compression are nil and can also be seen as such in the utilisation charts."

Is all/some of your data Thick-provisioned (either at the VM hard-disk level or via Storage Policy OSR=100)? I ask as Thick data won't benefit from deduplication.

What is the current % used space on your vsanDatastore? Deduplication and compression really only tend to come into their own with relatively higher utilisation as the more data on each Disk-Group the more likely common data will be present and can be deduplicated.

Does your data have a high degree of 'uniqueness' or is the data for each VM/disk likely to have a lot in common? Obviously the more unique data is the less it can be deduplicated.

"if not possible, Is it worth then to disable compression & de dupe considering the overhead de dupe & compression has?"

As with near every design decision in IT, everything is a trade-off - if none of the above points explain why you are achieving a net-loss (and/or whether it is feasible to resolve these or not) then do consider disabling this if you are not benefitting from it as it does have other caveats (e.g. one capacity-tier drive failed in a Disk-Group fails the whole Disk-Group).

Bob

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mschubi
Enthusiast
Enthusiast

Hello Sreejith,

if you have encrypted VMs the you store high randomly datas. Such datas has vanishingly small dedup/compression rates.

So better you disable compression/dedup.

But reminder - you need some free space to disable compression/deupe in a vSAN cluster because of changing the disk group metadatas....

best regards,

Mike

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sreejith1986
Contributor
Contributor

Hi TheBobkin,

Yes. They are other than VM encryption & VSAN Encryption.

All the disks are thin provisioned.

Thanks for all your inputs. Highly appreciated.

Regards,

Sree

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sreejith1986
Contributor
Contributor

Hi Mike,

Thank you. Highly appreciated.

Regards,

Sree

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