On Wed, Oct 30, 2019 at 12:17 PM Michael <mclaud@xxxxxxxxxxxxxx> wrote:
>
> Hi linux-btrfs,
>
> Step to reproduce
>
> 1) mkfs.btrfs -draid6 -mraid6 /dev/sd[abcdefgh]
>
> 2) mount
> -onoatime,nodiratime,thread_pool=24,max_inline=0,ssd_spread,compress-force=zstd
> /dev/sda /mnt/test/
Have you tried without raid6, like single disk device case for
example? And without compression?
Did such dramatic difference happened as well?
Thanks.
>
> 3) btrfs subvol create /mnt/test/subvol/
>
> 4) dd if=/dev/zero of=/mnt/test/subvol/test.dat bs=1M count=65536
>
> 5) btrfs subvol snapshot -r /mnt/test/subvol /mnt/test/subvol.ro
>
> 6) btrfs send /mnt/test/subvol.ro | pv >/dev/null
>
> 64,1GiB 0:01:18 [ 833MiB/s] - fast
>
> 7) for i in {1..16384}; do echo $i; printf '\x01\x02\x03' | dd
> of=/mnt/test/subvol/test.dat bs=1 seek=$(($i * 1024 * 1024)) count=3
> conv=notrunc; done
>
> 8) btrfs send /mnt/test/subvol.ro | pv >/dev/null
>
> I stop it at 0:01:18
>
> 464MiB 0:01:18 [4,67MiB/s] - very very slow
>
>
> uname -a
> Linux storage.domain.com 5.3.7-200.fc30.x86_64 #1 SMP Fri Oct 18
> 20:13:59 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
>
--
Filipe David Manana,
“Whether you think you can, or you think you can't — you're right.”
