Transforming a QLC SSD into an SLC SSD

Re:Transforming a QLC SSD into an SLC SSD by kasabali on Sunday May 19, 2024 @07:19AM (#40406108)

AFAIK Windows runs TRIM when you format a partition. So you can create a dummy partition and format it. Then you can either delete or simply not use it.

On Linux, blkdiscard can be used in the same manner (create a dummy partition and run blkdiscard on it ex. *blkdiscard /dev/sda2).

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Re:Transforming a QLC SSD into an SLC SSD by bravetraveler on Sunday May 19, 2024 @07:25AM (#40406139)

If one prefers working with LVM for their devices, that can be a similar wrench. Making/removing a logical volume can do the same

It depends on 'issue_discards' being set in the config

This has drifted over time. I haven't quite rationalized why. Hoping someone can remind me if nothing else, away from a real computer for a bit.

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Re:Transforming a QLC SSD into an SLC SSD by rzzzt on Sunday May 19, 2024 @07:43AM (#40406260)

You can go into Properties > Tools > Optimize, the same button that runs defrag on spinning drives runs TRIM on solid state devices.

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Re:Transforming a QLC SSD into an SLC SSD by formerly_proven on Sunday May 19, 2024 @08:20AM (#40406444)

Windows by default issues TRIMs basically instantly when deleting a file, and runs "Optimize disk" (which trims all free space) on a schedule by default as well.

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Re:Transforming a QLC SSD into an SLC SSD by FooBarWidget on Sunday May 19, 2024 @10:46AM (#40407312)

What about external SSDs over USB? How do you trim those?

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Re:Transforming a QLC SSD into an SLC SSD by wtallis on Sunday May 19, 2024 @12:04PM (#40407798)

There are trim-equivalent commands in the ATA, SCSI, and NVMe command sets. So the OS can issue the SCSI command to the USB device that's using UASP, and the bridge chip inside the external SSD can translate that to the ATA or NVMe counterpart before passing it on to the SSD controller behind the bridge. Not all external SSDs or bridge chips actually support trim passthrough, but these days it's standard functionality.

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Re:Transforming a QLC SSD into an SLC SSD by FooBarWidget on Sunday May 19, 2024 @02:23PM (#40408765)

I wonder how to do it on macOS then. I have several external SSDs and none of them can be trimmed.

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Re:Transforming a QLC SSD into an SLC SSD by wtallis on Sunday May 19, 2024 @02:54PM (#40408961)

https://kb.plugable.com/data-storage/trim-an-ssd-in-macos

Apparently macOS doesn't expose the ability for userspace to manually issue trim commands to block devices (or at least doesn't ship a suitable tool to do so), so the best available workaround is to tell the filesystem layer that it should do automatic trimming even on external drives.

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Re:Transforming a QLC SSD into an SLC SSD by ciupicri on Sunday May 19, 2024 @10:49AM (#40407330)

Create a partition that you'll never use and run blkdiscard [1] from util-linux on it.

[1]: https://man7.org/linux/man-pages/man8/blkdiscard.8.html / https://github.com/util-linux/util-linux/blob/master/sys-uti...

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Re:Transforming a QLC SSD into an SLC SSD by mananaysiempre on Sunday May 19, 2024 @11:37AM (#40407612)

The literal answer is yes, an ATA TRIM, SCSI UNMAP, or NVMe Deallocate command can cover whatever range on a device you feel like issuing it for. (The device, in turn, can clear all, none, or part of it.) On Linux, blkdiscard accepts the -o, --offset and -l, --length options (in bytes) that map more or less exactly to that. Making a(n unformatted) partition for the empty space and then trimming it is a valid workaround as well.

But you’re most probably doing this on a device with nothing valuable on it, so you should be able to just trim the whole thing and then allocate and format whatever piece of it that you are planning to use.

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