Which way to erase a M500 SSD will age it less?

hmh
Kilobyte Kid

Which way to erase a M500 SSD will age it less?

This one likely needs to be answered by Crucial support.

 

There are three ways to completely erase a M500 SSD without going into TCG commands:


ATA SECURITY ERASE

ATA SECURITY ERASE ENHANCED

full device TRIM  (untested by me)

 

I've tested the two ata security erase variants, and the enhanced security erase does not clear the "used pages" mappings. This is easily detected because blocks which were in use before the enhanced security erase will return random data after the enhanced security erase, while not previously written (or TRIMed) space will return zeroes.   For the record, this is either a bug, or a very undesired behavior of the firmware (for the record, M500 MU05).

 

Regular security erase will cause the drive to return all zeroes, so it does clear the FTL block-in-use information.  However, it is supposed to actually erase all user-data flash erase blocks, which AFAIK will age the flash.

 

I'd like to avoid aging the flash needlesly, as I don't need the "security" part of the erase, I just want the entire device erased and restored to no-blocks-in-use state.  But I am not going to assume how these three operations are really implemented by the device firmware.

 

Which method is less demanding on the device flash for the M500?  security erase, enhanced security erase + TRIM, or just TRIM ?

20 Replies
JEDEC Jedi

Re: Which way to erase a M500 SSD will age it less?

I don't know what enhanced secure erase is.  But google says not all drives support it.  So I guess this is one that doesn't if that's what your testing shows!

 

Doing a free space trim would only erase the areas of the drive available to the OS where as I presume secure erase would do all the NAND.  Both are doing erases rather than overwrites so both are good.  You'll know if you're doing it wrong drive life wise, because it will take much longer as it could only do it at drive write speed (500mb/sec or whatever) rather than erase speed (which is much faster)

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JEDEC Jedi

Re: Which way to erase a M500 SSD will age it less?

Q:  What is the difference between secure erase and enhanced secure erase?

A:  Secure erase overwrites all user data areas with binary zeroes.  Enhanced
secure erase writes predetermined data patterns (set by the manufacturer) to
all user data areas, including sectors that are no longer in use due to
reallocation. ***NOTE:  the enhanced secure erase option is not supported by
all ATA drives.

 

 

This is based on the assumption that you could recover data from a magnetic drive.  It's irrelevant on an SSD as you can't recover data and they'll be using erase rather than writing 0 or a pattern.

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JEDEC Jedi

Re: Which way to erase a M500 SSD will age it less?


@hmh wrote:

Regular security erase will cause the drive to return all zeroes, so it does clear the FTL block-in-use information.  However, it is supposed to actually erase all user-data flash erase blocks, which AFAIK will age the flash.



Wait... why would you 'regularly' secure erase a drive?  I've never secure erased on in my life.  In any case, if NAND contains data, and you want a blank drive, it has to erased at some point before it's next written too.  Whether that be part of your secure erase now or GC clearing it up later.  It won't make a long term difference.

 

 

Sorry for the 3 replies. I'm multi-tasking here. Smiley Very Happy

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JEDEC Jedi

Re: Which way to erase a M500 SSD will age it less?

I think he means regular as normal rather than periodic Smiley Happy

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JEDEC Jedi

Re: Which way to erase a M500 SSD will age it less?


@bogdan wrote:

I think he means regular as normal rather than periodic Smiley Happy


That would explain it. Smiley Very Happy  But then it's probably not worth worrying about the wear from a rare usage scenario?

 

The optimum choice wear wise would be in use OS trim rather than forcing a complete drive erase.  It would only erase what is needed.

 

 

According to this: http://www.overclock.net/t/1227597/how-to-secure-erase-your-solid-state-drive-ssd-with-parted-magic

SE erases everything - whether it needed it or not.  In fact, we've seen people with smart errors have their errors increment by SE so it probably doesn't even bother singling out dead NAND - never mind that which is already erased.

 

I don't know about trim.  As Windows 8 is designed to do this often - I'd like to think it's not that wear heavy!  Certainly my latest drive is still on 100% after 7 months use despite Windows 8.

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JEDEC Jedi

Re: Which way to erase a M500 SSD will age it less?

Right, I would say that most likely both ways, secure erase and full trim (W7/8 quick format as far as I can remember) should be quite equal wear wise (in general both should erase entire drive) and as long as your are not going to do it several times per day the wear created by them should be negligible.

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hmh
Kilobyte Kid

Re: Which way to erase a M500 SSD will age it less?

Apparently  I wasn't clear enough in my question...

 

1. The MU05 M500 does support three ways to erase it, on top of the TCG methods (e.g. PSID revert):  The two ATA SECURITY ERASE modes (normal and enhanced), and a full-device TRIM (doable in Linux using hdparm).

 

2. The MU05 M500 apparently fails to "trim the whole device", i.e. mark all blocks as "not in use" and safe to discard when garbage-collecting, when you issue an ATA SECURITY ERASE ENHANCED. This is likely a bug, or at least undesireable behavior.

 

The two points above are statements of fact. They have been verified to be true, although comments from someone that knows how the M500 firmware implements these functions would certainly be welcome.

 

I would like to know which of the three above ways to erase the SSD will age the flash less, and if any of them have performance drawbacks (apparently, just issuing ATA SECURITY ERASE ENHANCED does).

 

Meanwhile, I found this, which is likely relevant for the Crucial M500.

 

JEDEC Jedi

Re: Which way to erase a M500 SSD will age it less?

Your problem is... the people with the inside info on the firmware would be Micron's engineers.  We are a user to user forum for Crucial.  You're quite far removed from someone who can give you technical info on the firmware!  And that's assuming its internal workings aren't a secret like Indilinx's was.

 

The observations/speculation posted above are probably about s good as you're going to get. Smiley Happy

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JEDEC Jedi

Re: Which way to erase a M500 SSD will age it less?

I guess, as the erase count is stored in the SMART data, you could just try it.  secure erase the drive to ensure it's clear.  Note the erase count. Then SE and trim it a couple of times and see if any of them increase the erase count.

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