Re: Read-only snapshot send speed very slow after modify original data. Need help

[Michael <mclaud@roznica.com.ua>]

30.10.2019 14:38, Filipe Manana пишет:
> On Wed, Oct 30, 2019 at 12:17 PM Michael <mclaud@roznica.com.ua> 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.

without compression step 8: ~800MiB/s - fast

raid1, raid10, raid5, raid6, single drive step 8 with compression: ~4MiB/s

>
>> 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
>>
>

-- 
С уважением, Михаил
067-786-11-75