topic Re: Expansion Shelf SSD in Array Performance and Data Protection

Expansion Shelf SSD

sgreene11 — Thu, 31 Jul 2014 18:40:53 GMT

Hey,

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)?

Thanks!

Re: Expansion shelf SSD question

tmoore106 — Thu, 31 Jul 2014 19:16:56 GMT

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

Re: Expansion shelf SSD question

bgrieve65 — Thu, 31 Jul 2014 20:46:58 GMT

Shaun,

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

Re: Expansion Shelf SSD

rlabarre65 — Wed, 13 Aug 2014 17:12:56 GMT

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.