Re: Btrfs keeps getting corrupted

[Roman Mamedov <rm@romanrm.net>]

On Mon, 16 Sep 2024 06:59:54 +0930
Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:

> > Such a high disparity in transid mismatch, flush is not working somewhere? But
> > I specifically do "sync" even multiple times now, before unmounting and after.
> 
> Manually sync still relies on FLUSH, and FLUSH is not working on the
> lower storage stack (from LUKS to your SSD/HDD firmware), sync won't
> save you.

I always kept in mind that 'sync' was the key to ensure all data has been
moved from RAM to the HDD. But I now realize that I missed that there's also a
buffer in the HDD, which also needs to be flushed to disk. It could be that I
power-off the device before it manages to do that. Also it is an SMR HDD, so
it might need to do housekeeping with the data on-disk as well.

One idea I got is sending drive to sleep (hdparm -Y) before calling power-off
now. Hopefully that makes it flush before sleep.

> > How can I figure out what is to blame here, is it the enclosure, is it USB,
> > LUKS, Btrfs, or some fundamental bug involving a combination of these?
> 
> In that case, you may want to provide your kernel version first (to rule
> out known bugs or too old kernels), then reduce the depth of the storage
> stack, aka, running btrfs directly on that device as a test.

The kernel is 6.6 series, cannot say exact, but was at most 5-10 point
releases older than latest, both of the times the issue occured.

-- 
With respect,
Roman