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help computing SSD wearout

Esteemed Contributor III

I have an application where I'm trying to compute wearout - I'm considering using 520 or 710 SSDs -- of course the 520 line comes at a very attractive price/performance point as compared to the 710 offering extended reliability.

My application does continuous very small random writes, so I think I'm basically limited by program/erase cycles of the underlying flash that's used. So, say for a given number of writes per second, how long would I expect a drive to last?

Here is a link to a spreadsheet I worked up which shows approximate lifetime in days as a function of the erase block size assuming the drive is completely full:

So, if this is correct, what is the actual erase block size on these disks, and what is the approximate number of erase cycles per block?

How does over provisioning effect this picture if say we under allocate the disk by say 10-20% or more?




Esteemed Contributor III

Minimum erase block is 128kb, and wirite is 8192 as I heard. So I'm not sure.