boka1

SSD Data Retention Depending on File Use and Power Supply

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Hi,

I am currently considering whether to get a laptop with an SSD. After doing some research I am still left with a couple of important questions to which I could not find a clear answer:

1) What is the data retention time when the SSD is regularly switched on and off?

2) Is the retention time shorter for data that are not being used?

I know that, depending on the specifics of the SSD, data retention can be short (in the order of months to a few years) when the SSD is left powered off. However, I am talking of a situation where the SSD is regularly powered on and off as you would in normal laptop use, but some data are read/rewritten much less frequently than others.

As an example, let’s say that you have 2 identical SSDs with some pictures on them. One of these you power off and store; the other one you keep using daily inside your laptop, but some of the pictures you view/modify often, whereas others you never touch.

1) Will the data on the SSD that you use be retained longer than on the SSD that was powered off (assuming you never reach the limit of supported read/write cycles for the SSD that is in use)?

2) Will data in the files you use be retained longer than in the files you don’t use within the SSD that is in your laptop (with the same assumption as above)?

I found a partially overlapping question asked on this forum (), but unfortunately from it I could not derive a clear answer to what I'm interested in.

Thanks a lot for your help! :)

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Data retention is generally thought to be about three months without power. The individual files don't matter, it's about power to the drive in general.

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Data retention is generally thought to be about three months without power. The individual files don't matter, it's about power to the drive in general.

Dear Brian, thank you for your reply!

My question however was rather related to the situation with power. How long is the retention time when the power is regularly switched on and off (i.e. in normal use)? And the second question is: when the power is regularly switched on and off, does it matter if the individual files are used or not? To put it another way, if the SSD is powered on but some files are never used, do these files degrade faster (as if the drive had been powered off just for these files)?

Thanks! :)

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Actually, retention on consumer drives should be at least a year .... at least while the drive hasn't used all it's erase cycles.

A fresh out of the box drive may however be good for 5 years or more retention.

For SSDs which are powered on regularly, the controller should be scrubbing the NAND, finding weak cells, and rewriting them elsewhere, so retention should be nearly infinite.

Edited by rugger

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Actually, retention on consumer drives should be at least a year .... at least while the drive hasn't used all it's erase cycles.

A fresh out of the box drive may however be good for 5 years or more retention.

For SSDs which are powered on regularly, the controller should be scrubbing the NAND, finding weak cells, and rewriting them elsewhere, so retention should be nearly infinite.

Thanks for the feedback, it does address my concerns. :D

Companies seem to be rather frugal on details about whether and how they employ scrubbing for their SSDs, though - I couldn't really find anything relevant at Intel, OCZ, SanDisk, Kingston, Crucial... :unsure:

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The length of powerless retention can vary considerably, I would not rely on anything past 3 months if it were my critical data...SSDs just aren't designed for long term retention.

As to the initial question, you don't have to access the files, you just need to power the drive so it can go through it's processes.

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Query: source for the 3 month or 1 year or whatnot numbers?

IIRC I have 1 year or 5 year laying around somewhere, but I'm not sure on the source off the top of my head. :(

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Query: source for the 3 month or 1 year or whatnot numbers?

IIRC I have 1 year or 5 year laying around somewhere, but I'm not sure on the source off the top of my head. :(

Page 26:

http://www.jedec.org/sites/default/files/Alvin_Cox%20%5BCompatibility%20Mode%5D_0.pdf

For client drives, minimum 1 year for powered off data retention.

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I didn't realize there was a data retention over time issue. I have a bunch (hundreds) of Intel 80GB G2 drives laying around that only get connected to a machine a couple times a year, if that. I am not aware of any data loss yet, I guess I should make a point to plug them in every so often. I also have a few machines out at customer sites that only get powered up a couple times a year, lots of spare machines that have only been powered up once - likely in 2009 or 2010. Suddenly the Velociraptors are looking more appealing...

Suddenly I am wondering if the issues I had with the Micron C200 drives could be in some way related to this.

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Most SSDs for consumer use will retain data for at least five years, even though the spec for MLC requires 1 year of data retention without power.

For SLC the spec requires 10 years.

For enterprise the retention period has been shortened to 3 months.

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Ah-- duh, should've thought about JEDEC spec.

cbrworm, that's just the spec, it should last longer. Harddisks have similar spec limits as well.

Just be aware that the retention gets worse as a drive ages. As each flash cell wears from erase and program cycles, the floating gate loses it's ability to retain a charge over a long period of time.

So when you have a fresh out the box SSD, retention will be very good, possibly even 10 years or more. However, apply 3000 or 5000 write cycles to the NAND and retention will drop quite a lot ... possibly as low as a year (but probably a fair bit longer still)

This is why enterprise specifications only call for 3 months retention at end of life. This means you can use the flash cells for longer before they go out of spec, allowing for higher write applications.

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