On 28/10/2021 22:59, Sworddragon wrote:
Despite I'm not using Linux as main system anymore and wanted to avoid
getting into too much work I found some time to do some tests as this issue
bugs me just too much.
You could try running the following immediately after,
to see if it also returns quickly:
blockdev --flushbufs /dev/sdb
Yes, this command also blocks for a bit over 1 minute when this issue
occurs.
Right, so that suggests conv=fsync on dd was ineffective.
Here is the output (I had to freely translate the strings since
this Knoppix instance is only in german so they might be slightly
inaccurate; Also I had to type all text since it was executed on a
different system but carefully checked to not introduce any typos):
root@Microknoppix:~# dd if=/dev/random of=/dev/sdb bs=1M conv=fsync
status=progress
1039138816 Bytes(1,0 GB, 991 MiB) copied, 56 s, 18,5 MB/s
dd: Error on writing '/dev/sdb': The device has not enough free space
999+0 records in
998+0 records out
Ah right. What's probably happening is that dd is not doing the fsync
because it's exiting early because of the ENOSPC from write(2).
To avoid needing the buffer drain (with fsync), you can use
