Not so fast folks!
As always, we're trying different things. I recently used some older parts and created a Server with 2.6.39 (Debian) that has a 3ware card and a Btrfs filesystem. LVM was placed on top of the 3ware partition and then Btrfs was put on top of that. The storage was shared out via NFS for an ESXi host.
I was expecting the system to work okay and it did for about a month. Eventually the volume needed more space, so the Btrfs volume was resized and life continued. About a week ago the system performance became unacceptable. VERY slow, high load averages, 80+% IO wait, etc. In addition, the VM would no longer boot because ESXi was complaining about disk IO timeouts! I was definitely experiencing some major performance issues. All of the hardware I was using was pretty much old, but tried and true. Being Btrfs was new on the scene and the strange behavior the kernel was displaying, I suspected the shiny Btrfs. I created a new Reiserfs (v3) volume, which in the past (and apparently still is) was my file-system of choice. I copied the VMDK and associated goodies to the new volume, shared it out, and ESXi was in heaven again.
So, what I have learned is:
1. Btrfs has some issues with NFS. The performance appeared perfecetly fine coping the data from Btrfs to Reiserfs, but accessing the data via NFS was awful.
2. Btrfs performance degrades over time. Initially the VM worked great. Over time, performance degraded until it was basically no longer usable.
I haven't yet determined exactly why I experienced these issues with Btrfs, but Reiserfs seems to have solved it for now. I'll definitely be looking for clues in the coming months.
Lastly, some data on backup times the VM logs. (The VM is responsible for backing up other servers. These times are for one small server that is backed up to the VM's storage). The last 1 minute time is after switching to Reiserfs.
Duration: 1 min. Duration: 1 min. Duration: 1 min. Duration: 0 min. Duration: 1 min. Duration: 1 min. Duration: 1 min. Duration: 3 min. Duration: 1 min. Duration: 8 min. Duration: 10 min. Duration: 39 min. Duration: 12 min. Duration: 59 min. Duration: 109 min. Duration: 66 min. Duration: 3 min. Duration: 240 min. Duration: 297 min. Duration: 298 min. Duration: 657 min. Duration: 375 min. Duration: 2140 min. Duration: 1 min.