FYI - after a failed disk and replacing it I've run a balance; it took almost 3 weeks to complete, for 120 GBs of data: # time btrfs balance start -v /home Dumping filters: flags 0x7, state 0x0, force is off DATA (flags 0x0): balancing METADATA (flags 0x0): balancing SYSTEM (flags 0x0): balancing Done, had to relocate 124 out of 124 chunks real 30131m52.873s user 0m0.000s sys 74m59.180s Kernel is 3.17.0-rc7. Filesystem is not that big, merely 124 GB used out of 1.8 TB: /dev/sdb4 1.8T 124G 1.6T 8% /home # btrfs fi df /home Data, RAID1: total=121.00GiB, used=117.56GiB System, RAID1: total=32.00MiB, used=48.00KiB Metadata, RAID1: total=8.00GiB, used=4.99GiB GlobalReserve, single: total=512.00MiB, used=0.00 # btrfs fi show /home Label: none uuid: 84d087aa-3a32-46da-844f-a233237cf04f Total devices 2 FS bytes used 122.56GiB devid 2 size 1.71TiB used 129.03GiB path /dev/sdb4 devid 3 size 1.71TiB used 129.03GiB path /dev/sda4 The only special thing about this filesystem is that there are ~250 snapshots there: # btrfs sub list /home|wc -l 253 It's using compression: /dev/sdb4 on /home type btrfs (rw,noatime,compress=lzo,space_cache) Other than taking occasional backups from remote, the server is idle. # hdparm -t /dev/sda /dev/sdb /dev/sda: Timing buffered disk reads: 394 MB in 3.01 seconds = 131.03 MB/sec /dev/sdb: Timing buffered disk reads: 402 MB in 3.00 seconds = 133.86 MB/sec How long does the balance take for others with "many" snapshots? -- Tomasz Chmielewski http://www.sslrack.com -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html