Suitability in a VM storage environment, L2 Write Cache ?'s Topic is solved

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rwohleber
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Suitability in a VM storage environment, L2 Write Cache ?'s

Post by rwohleber »

We are considering using PrimoCache in our Hyper-V SAN and it is populated with about 30x large VHDX files (greater than 100GB in size, some are upwards of 1TB). My question is if the Read cache works on a block level or a file level? Also with the L2 Storage Write Cache, will that be helpful for large file write updates where the file is kept open all the time (again, VHDX files)?

We have no problem allocating 3x 1TB NVme sticks (different manufacturers obviously) to be a mirrored write cache, but we don't want to pursue this strategy if this is a file Cache as opposed to a block Cache or if it won't be effective for our use case.

I want to get FreeNas out of the DC - we've had a couple bad experiences which I won't bore you with.

TIA!

Rick
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Jaga
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Re: Suitability in a VM storage environment, L2 Write Cache ?'s

Post by Jaga »

Primocache works at the block level. Whatever block size you setup, it will fetch from the volume (no matter what cluster size is set). It is recommended to keep block size and cluster size either equal, or to use a slightly larger block size (to reduce overhead).

The write cache is definitely useful when large writes are concerned. It reduces the sustained write time, which it can then spread out over a larger period afterwards.
rwohleber
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Re: Suitability in a VM storage environment, L2 Write Cache ?'s

Post by rwohleber »

Very cool, thanks! Block level cache is ideal for our environment, obviously.

Rick
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