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Why disable RAID caching on deduplication storage folder?

I'm in the process of setting up BE 2010 R3 and I've seen in the best practices for deduplication that I should disable RAID caching for the deduplication storage folder. I have a volume on our SAN dedicated for the deduplication storage folder as the best practices state. But why would I disable the RAID cache on it? Won't this hurt performance to disable the RAID cache? Does it mean to disable the read and write cache?

2 Replies

...the only thing I can think

...the only thing I can think of is that dedupe might become affected (either corruption or speed-wise) during the dedupe process if the cache is involved.

Maybe the way the cache would try reading ahead would cause some corruption when transferring data to the dedupe store, while disabling it means the data hits the disks without any sort of 3rd-party interference.

I've also hit the support flag on this one so hopefully someone from Symantec picks up on this and gives more information!


They've recommended this in

They've recommended this in other cases too with backup products, it's not limited to the dedupe function only..

I strongly feel that this is a CYA part of Symantec in the odd case that RAID cache causes data corruption upon write.

Symantec also needs to clarify if it's write-back or write-thrrough as the bad apple.  My guess is that Symantec prefers write-through to write direct to disk, and caching for faster restore access.