Hi guys,
My Btrfs fs has a performance problem which I hope you can help me
solve. I have a dataset of around 3.15 TiB, that has lived on a ZFS
volume for almost two years (ZRAID1, 4 2TiB disks). In order to move
to Btrfs I bought myself a 4TiB disk with the idea of buying a new one
next week and balance it to a RAID1 of 2 4TiB disks.
I created a single disk Btrfs volume with the default mkfs options (no
data duplication, metadata duplication on). Next I transferred my
dataset to this disk (no problems there). Today when I tried to create
a directory and I noticed the Btrfs volume was awefully slow; it took
a few seconds to create the directory and a few to delete it (which
should be milliseconds as you know). In fact each and every operation
on the volume grinded the fs down to a halt.
FS information:
# btrfs fi df /storage
Data: total=3.29TB, used=3.15TB
System, DUP: total=8.00MB, used=360.00KB
System: total=4.00MB, used=0.00
Metadata, DUP: total=4.00GB, used=3.88GB
Metadata: total=8.00MB, used=0.00
# btrfs fi show
Label: 'storage' uuid: 3fa262cd-baa9-46dc-92a8-318c87166186
Total devices 1 FS bytes used 3.16TB
devid 1 size 3.64TB used 3.30TB path /dev/sdb
I suspect my performance blow has everything to do with the abysmally
low amount of space for metadata that is left, but since I am not a
Btrfs guru I don't now whether this is truly the case and/or how to
solve it. btrfs fi balance start -dusage=5 did not help.
Yours,
John
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