As a counter-argument, I use BTRFS on a filesystem with about 280TB raw right now as a
fileserver. Note that this is mostly transient data (raid 0), and I have stuck with 3.14,
hearing the horror stories of 3.15/3.16 locking up.
Even at that size (29TB LUNs), I have been able to add and remove devices and rebalance
with no issues other than it causing increased IO and taking several weeks to move that
much data around.
Definitely avoid 3.15/3.16 and test out your workload first if possible to make sure it
performs properly. Also build the filesystem and put data on it and test device
removals/rebuilds to make sure it works with your OS, btrfs tools, and kernel version.
All that being said it works great for us where we value COW and expansion/rebalancing
over performance and redundancy.
The filesystem is exported via NFS and rsync to over 200 clients over 10gb/sec ethernet,
and hits around 5-7gb/sec balanced between reads and writes.
One of our alternative file storage needs that I'd also hoped to move to BTRFS consisted
of subtrees of 255 directories, each with 255 directories under them, and 255 directories
under them with 1 file in each (don't ask). That *did not* work well under BTRFS --
probably due to the metadata juggling required in creating or removing any one file that
far down in such a bizarre tree. We kept that particular area under XFS.
-ben
Tomasz Chmielewski wrote:
we are thinking about using BtrFS on standard hardware for a
fileserver with about 50T (100T raw) of storage (25×4TByte).
I would recommend carefully reading this thread titled: "1 week to
rebuid 4x 3TB raid10 is a long time!"
So I have a 2 x 2.6 TB devices in btrfs RAID-1, 716G used. Linux 3.16.
One of the disks failed.
"btrfs device delete missing /home" is taking 9 days so far, on an idle system:
root 4828 0.3 0.0 17844 260 pts/1 D+ Aug11 38:18 btrfs device delete missing /home
There is some kind of btrfs debug info printed in dmesg which seems to tell me that the
operation is working, like:
[744657.598810] BTRFS info (device sda4): relocating block group 908951814144 flags 17
[744672.021612] BTRFS info (device sda4): found 4784 extents
[744688.604997] BTRFS info (device sda4): found 4784 extents
[744689.133397] BTRFS info (device sda4): relocating block group 910025555968 flags 17
[744701.162678] BTRFS info (device sda4): found 4196 extents
[744725.000459] BTRFS info (device sda4): found 4196 extents
but other than that, the recovery time doesn't look optimistic to me, there is no ability
to check the progress etc.
--
-----------------------------
Benjamin O'Connor
TechOps Systems Administrator
TripAdvisor Media Group
boconnor@xxxxxxxxxxxxxxx
c. 617-312-9072
-----------------------------
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