Flash Memory Summit 2014 Spreadsheet

I am posting the spreadsheet that accompanies the Flash Memory Summit 2014 Seminar A chart deck. This is a LibreOffice 4 spreadsheet. Note that it includes a macro that extends the range of the cumulative binomial distribution. Interestingly, LibreOffice suffers from the same lack of precision that Excel does. The macro is provided as-is, and is not guaranteed to work in all cases. [Translation: I haven’t had time to debug it and the error handling in LibreOffice basic is abysmal.]

The spreadsheet shows how to compute reliability for flash-based storage systems, and compares various RAID  architectures when using a DNR ECC approach (described in the chart deck).

Note: I have seen a lot of talk in the industry about how new systems use erasure codes instead of RAID. Technically, all RAID designs use erasure codes – even mirroring (that’s called a replication code). I use the term RAID loosely to describe a system utilizing an erasure code  to protect against data loss.

The PMDS codes described here are erasure codes designed to protect against simultaneous device loss and sector loss with high data efficiency. You can read about them here, here and here.

You can download the RAID Reliability Spreadsheet.

The spreadsheet is provide under GPLv2.

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