Diggin' technology every day

February 19, 2011

Flash not good for offline storage?

Filed under: Random Thought,Storage — Tags: , , — Nate @ 9:36 am

A few days ago I came across an article on Datacenter Knowledge that was talking about Flash reliability. As much as I’d love to think that just because it’s solid state that it will last much longer, real world tests to-date haven’t shown that to be true in many cases.

I happened to have the manual open on my computer for the Seagate Pulsar SSD, and just saw something that was really interesting to me, on page 15 it says –

As NAND Flash devices age with use, the capability of the media to retain a programmed value begins to deteriorate. This deterioration is affected by the number of times a particular memory cell is programmed and subsequently erased. When a device is new, it has a powered off data retention capability of up to ten years. With use the retention capability of the device is reduced. Temperature also has an effect on how long a Flash component can retain its pro-grammed value with power removed. At high temperature the retention capabilities of the device are reduced. Data retention is not an issue with power applied to the SSD. The SSD drive contains firmware and hardware features that can monitor and refresh memory cells when power is applied.

I am of course not an expert in this kind of stuff, so was operating under the assumption that if the data is written then it’s written and won’t get  “lost” if it is turned off for an extended period of time.

Seagate rates their Pulsar to retain data for up to one year without power at a temperature of 25 C (77 F).

Compare to what tape can do. 15-30 years of data retention.

Not that I think that SSD is a cost effective method to do backups!

I don’t know what other manufacturers can do, I’m not picking on Seagate, but found the data tidbit really interesting.

(I originally had the manual open to try to find reliability/warranty specs on the drive to illustrate that many SSDs are not expected to last multiple decades as the original article suggested).

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