Will device-based “wear leveling” equalize access across both SSD partitions?

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I can’t see that my specific point is covered by the “Wear Levelling” section in the answer to the earlier question Disadvantages of partitioning an SSD?

I’ve been booting Windows 7 from a 32GB SSD for some time with no problems. I don't keep docs/data on the boot drive, so it’s barely half-full. But I just treated myself to a new 64GB SSD, mainly because the old one is noticeably slow at writing.

I want to split the new SSD into two equal-sized partitions, with the “non-boot” one only accessed occasionally using Paragon to create a full system backup of the boot drive, which I copy over my home network to a different machine for absolute security.

Will device-based “wear leveling” equalize access across both partitions? If not, I suppose I could “swap” the two partitions at some point in the future, but I’d rather not have to.

FumbleFingers

Posted 2015-04-14T16:54:43.900

Reputation: 357

Answers

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So long as the operating system you are using supports the trim command then unused blocks, irrespective of their logical placement on the drive, will be returned to the wear levelling pool and will therefore be available for wear levelling across the drive.

It helps to not think of an SSD as the physical drive that you partition yourself, as is the case with a standard HDD. What you "partition" on an SSD is actually the space on-top of another filesystem that itself is on top of the raw block device.

As a rather simplistic view, between you and the actual flash blocks is a flash transition layer or similar that does the wear levelling:

enter image description here
Image from
https://www.usenix.org/legacy/event/fast08/tech/full_papers/kim/kim_html/index.html

It is upon this FTL layer that your partitions sit, not the actual flash.

As an example, if you were at some point to delete and repartition your drive it is entirely possible that your partition headers would get wear levelled and could potentially be placed in a completely different physical flash block than they were originally. It is up to the wear levelling algorithm to decide how and where to put any data.

Mokubai

Posted 2015-04-14T16:54:43.900

Reputation: 64 434

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Okay, well I know Win7 on my system correctly recognises both devices as ssd's, since it doesn't want to defrag them. I guess I'll have to follow the instructions at How can i know if TRIM command is working on windows 7 to confirm if that aspect is okay. I'll worry about what to do next if and when I discover it isn't okay. Thanks.

– FumbleFingers – 2015-04-14T17:16:10.063

1TRIM should be enabled out of the box on Windows 7 if it is detected as a SSD. – Ramhound – 2015-04-14T18:01:41.153