Ubuntu

Can't execute TRIM on Mushkin SSD

Asked by littlemike

I recently replaced my four 1TB SATA hard drives in software RAID 5 configuration on my Ubuntu 20.04 system with four 1TB SATA Mushkin SSDs (model MKNSSDS21TB). I perfomed a "dd" copy for each drive-to-drive duplication. There's two EXT 4 filesystems (/ and /home) on the RAID. The copy and install went fine and it was up and running with no problems. I then tried to ensure the weekly TRIM operation was set up (preferred over the "discard" fstab entry).

At that point, I found that fstriim would not run on the filesystems -- it returns: "fstrim: /: the discard operation is not supported". Mushkin specifications states TRIM is supported. "hdparm" reports that the drives support TRIM. The "/sys/block/sdX/device/scsi_disc/0:0:0:0:/provisioning_mode" contains "writesame_16" and "/sys/block/sdX/queue/rotational" contains "0" so the kernel has the information to know it's an SSD with TRIM support. And all the literature states TRIM is supported on linux software raid -- (mdadm)RAID456 has supported discards since 2016.

Can someone steer me in the right direction to get the TRIM operation to succeed? The performance of the drives is rapidly decreasing.

Thanks!

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actionparsnip (andrew-woodhead666) said : 		#1

If you run:

sudo fstrim -v /

Does it run OK?

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littlemike (fletchermichael) said (last edit ): 		#2

Thanks for the reply. As indicated above, I get:

"fstrim: /: the discard operation is not supported"

However, I can report I've found the problem: by default, the raid456 kernel module disables TRIM/discard. The user has to affirmatively ensure the devices support TRIM and enabling it by adding the following kernel command line parameter (via the grub config file /etc/default/grub and running update-grub):

"raid456.devices_handle_discard_safely=Y"

or putting the following in /etc/modprobe.d/raid456.conf:

"options raid456 devices_handle_discard_safely=Y"

I used the kernel command line option.
My problem is solved.