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Expansion Shelf SSD

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Expansion Shelf SSD


We have a fairly small amount of data but tend to have a lot of cache misses (~25%).  I think this is probably to do with backups but it does happen during the day as well.

Anyways, my question - when we add an expansion shelf to our 420, if we go with the 15TB shelf (which only has a 160GB SSD) can we upgrade the SSD to say, a 600GB SSD instead?  Or is our only option to either upgrade the cache on the main array (it's an X2)?


Trusted Contributor

Re: Expansion shelf SSD question

The SSD size in the shelf is fixed. You can upgrade the arracy cache, or add an AFS.

Valued Contributor

Re: Expansion shelf SSD question


I concur with Todd's response. I would also add that while you may get an opportunistic hit from cache on the expansion shelf's SSD, it is primarily used to store the metadata for that particular shelf. I wouldn't count on that as a method to expand the cache pool for your working set.

Brandon Grieve

Occasional Advisor

Re: Expansion Shelf SSD

One thing that customers are seeing a lot of value in with regards to the All Flash shelf is that its not only priced right, but you keep the existing cache in your head unit (thus allowing for further upgrades, to 2.4TB in your 400 series), while also growing 3.2TB at a time on the AFS.  You never lose your initial investment with Nimble. Add when you want, how you want.