Hi You can destroy the fastcache and reuse the disks. the operation will cause all the data in the fast cache to be destaged to disk, and this can have a performance impact on your array, and take quite a long time. And remember that this is on top of not having any fast cache...So of your array has the overhead to do this no problems, but if it has been designed to just meet your IOPS with the Fastcache included in the IOPS calculations, this may not be a good idea.

How are you going to test with 2 EFDs? A raid 1 group ?

When the array was spec'd it didn't include any FAST cache in the original design. We later added this as a bonus due to some extra budget. Once we've finished testing the SSD's is it just a case of re-creating the FAST cache and off we go?

That's my next question. What's the recommended RAID for SSDs?

I suspect we'd probably go down the RAID 10 route if we were going to purchase additional disks as a result of the tests. Depends how much they want to spend though as 1600 per disk isn't cheap!

can't do a whole lot with 2 drives, mirror only (that's how Fast Cache is configured as well). I am trying to sqeeze as much usable capacity, so i always use RAID-5 for EFDs.

It is worth noting that during the process of creating and destroying Fast Cache, the SP Cache is temporarily disabled.  Therefore, in the case of SP write cache, it will be disabled for as long as it takes to destage its contents. 

I simply want to mention this as during that time while data is still of course accessible throughout the process, you may want to consider this when you schedule the activity.

It is better to first disable FAST Cache per LUN / pool – which does the destaging – before destroying FAST Cache

You can do that via GUI or navicli

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glen