Re: mount time of multi-disk arrays

["André-Sebastian Liebe" <andre@lianse.eu>]

On 07/07/2014 03:54 PM, Konstantinos Skarlatos wrote:
> On 7/7/2014 4:38 μμ, André-Sebastian Liebe wrote:
>> Hello List,
>>
>> can anyone tell me how much time is acceptable and assumable for a
>> multi-disk btrfs array with classical hard disk drives to mount?
>>
>> I'm having a bit of trouble with my current systemd setup, because it
>> couldn't mount my btrfs raid anymore after adding the 5th drive. With
>> the 4 drive setup it failed to mount once in a few times. Now it fails
>> everytime because the default timeout of 1m 30s is reached and mount is
>> aborted.
>> My last 10 manual mounts took between 1m57s and 2m12s to finish.
> I have the exact same problem, and have to manually mount my large
> multi-disk btrfs filesystems, so I would be interested in a solution
> as well.
Hi Konstantinos , you can workaround this by manual creating a systemd
mount unit.

- First review the autogenerated systemd mount unit (systemctl show
<your-mount-unit>.mount).  You you can get the unit name by issuing a
'systemctl' and look for your failed mount.
- Then you have to take the needed values (After, Before, Conflicts,
RequiresMountsFor, Where, What, Options, Type, Wantedby) and put them
into an new systemd mount unit file (possibly under
/usr/lib/systemd/system/<your-mount-unit>.mount ).
- Now just add the TimeoutSec with a large enough value below [Mount].
- If you later want to automount you raid, add the WantedBy under [Install]
- now issue a 'systemctl daemon-reload' and look for error messages in
syslog.
- If there are no errors you could enable your manual mount entry by
'systemctl enable <your-mount-unit>.mount' and safely comment out your
old fstab entry (systemd no longer generates autogenerated units).

-- 8< ----------- 8< ----------- 8< ----------- 8< ----------- 8<
----------- 8< ----------- 8< -----------
[Unit]
Description=Mount /data/pool0
After=dev-disk-by\x2duuid-066141c6\x2d16ca\x2d4a30\x2db55c\x2de606b90ad0fb.device
systemd-journald.socket local-fs-pre.target system.slice -.mount
Before=umount.target
Conflicts=umount.target
RequiresMountsFor=/data
/dev/disk/by-uuid/066141c6-16ca-4a30-b55c-e606b90ad0fb

[Mount]
Where=/data/pool0
What=/dev/disk/by-uuid/066141c6-16ca-4a30-b55c-e606b90ad0fb
Options=rw,relatime,skip_balance,compress
Type=btrfs
TimeoutSec=3min

[Install]
WantedBy=dev-disk-by\x2duuid-066141c6\x2d16ca\x2d4a30\x2db55c\x2de606b90ad0fb.device
-- 8< ----------- 8< ----------- 8< ----------- 8< ----------- 8<
----------- 8< ----------- 8< -----------


>
>>
>> My hardware setup contains a
>> - Intel Core i7 4770
>> - Kernel 3.15.2-1-ARCH
>> - 32GB RAM
>> - dev 1-4 are 4TB Seagate ST4000DM000 (5900rpm)
>> - dev 5 is a 4TB Wstern Digital WDC WD40EFRX (5400rpm)
>>
>> Thanks in advance
>>
>> André-Sebastian Liebe
>> --------------------------------------------------------------------------------------------------
>>
>>
>> # btrfs fi sh
>> Label: 'apc01_pool0'  uuid: 066141c6-16ca-4a30-b55c-e606b90ad0fb
>>          Total devices 5 FS bytes used 14.21TiB
>>          devid    1 size 3.64TiB used 2.86TiB path /dev/sdd
>>          devid    2 size 3.64TiB used 2.86TiB path /dev/sdc
>>          devid    3 size 3.64TiB used 2.86TiB path /dev/sdf
>>          devid    4 size 3.64TiB used 2.86TiB path /dev/sde
>>          devid    5 size 3.64TiB used 2.88TiB path /dev/sdb
>>
>> Btrfs v3.14.2-dirty
>>
>> # btrfs fi df /data/pool0/
>> Data, single: total=14.28TiB, used=14.19TiB
>> System, RAID1: total=8.00MiB, used=1.54MiB
>> Metadata, RAID1: total=26.00GiB, used=20.20GiB
>> unknown, single: total=512.00MiB, used=0.00
>>
>>
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>
> -- 
> Konstantinos Skarlatos
--
André-Sebastian Liebe