Re: FSTRIM timeout/errors on WD RED SA500 NAS SSD

[Roman Mamedov <rm@romanrm.net>]

On Sat, 25 Jun 2022 00:45:55 +0200
Forza <forza@tnonline.net> wrote:

> I have tried lowering the discard_max_bytes, but it did not help - on 
> the contrary it takes much longer to do the blkdiscard /dev/sdf and does 
> not solve the problem.

Should be possible to verify exactly which size discard requests are being
submitted to the device, using https://linux.die.net/man/8/blktrace

In no event requests larger than discard_max_bytes should be seen.

If lowering it does not help, perhaps after a sustained stream of those,
some individual requests, even small, start to take longer than 30s?

> However, since btrfs-progs do split discard ranges into smaller chunks, 
> and that ext4 seems to handle this as well, I think it is worth looking 
> into handling.

That's not something to be handled on the FS side, even if one of them
happens to work, by luck. I suggest to focus on diagnosing with blkdiscard
only, and proceed to FSes only after that has been made to work reliably.

-- 
With respect,
Roman