On 01/08/17, E V wrote:
> In general I think btrfs takes time proportional to the size of your
> metadata to mount. Bigger and/or fragmented metadata leads to longer
> mount times. My big backup fs with >300GB of metadata takes over
> 20minutes to mount, and that's with the space tree which is
> significantly faster then space cache v1.
>
Hmm my raid1 doesn't seem near to full or has a significant Metadata so
I don't I'm on this case:
# btrfs fi show /media/raid1/
Label: 'raid1' uuid: c9db91e6-0ba8-4ae6-b471-8fd4ff7ee72d
Total devices 2 FS bytes used 516.18GiB
devid 1 size 931.51GiB used 518.03GiB path /dev/sdd
devid 2 size 931.51GiB used 518.03GiB path /dev/sde
# btrfs fi df /media/raid1/
Data, RAID1: total=513.00GiB, used=512.21GiB
System, RAID1: total=32.00MiB, used=112.00KiB
Metadata, RAID1: total=5.00GiB, used=3.97GiB
GlobalReserve, single: total=512.00MiB, used=0.00B
I tried the space_cache=v2 just to see if it would do any
difference but nothing changed
# cat /etc/fstab | grep raid1
UUID=c9db91e6-0ba8-4ae6-b471-8fd4ff7ee72d /media/raid1 btrfs rw,noatime,compress=lzo,space_cache=v2 0 0
# time umount /media/raid1 && time mount /media/raid1/
real 0m0.807s
user 0m0.237s
sys 0m0.441s
real 0m5.494s
user 0m0.618s
sys 0m0.116s
I did a couple of rebalances on metadata and data and it improved a bit:
# btrfs balance start -musage=100 /media/raid1/
# btrfs balance start -dusage=10 /media/raid1/
[.. incremental dusage 10 -> 95]
# btrfs balance start -dusage=95 /media/raid1
Down to 3.7 sec
# time umount /media/raid1 && time mount /media/raid1/
real 0m0.807s
user 0m0.237s
sys 0m0.441s
real 0m3.790s
user 0m0.430s
sys 0m0.031s
I think maybe the next step is to disable compression if I want to mount
it faster. Is this normal for BTRFS that performance would degrade after
some time?
Regards,
--
Leonidas Spyropoulos
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