On 07/07/2014 04:14 PM, Austin S Hemmelgarn wrote: > On 2014-07-07 09:54, Konstantinos Skarlatos wrote: >> On 7/7/2014 4:38 μμ, André-Sebastian Liebe wrote: >>> Hello List, >>> >>> can anyone tell me how much time is acceptable and assumable for a >>> multi-disk btrfs array with classical hard disk drives to mount? >>> >>> I'm having a bit of trouble with my current systemd setup, because it >>> couldn't mount my btrfs raid anymore after adding the 5th drive. With >>> the 4 drive setup it failed to mount once in a few times. Now it fails >>> everytime because the default timeout of 1m 30s is reached and mount is >>> aborted. >>> My last 10 manual mounts took between 1m57s and 2m12s to finish. >> I have the exact same problem, and have to manually mount my large >> multi-disk btrfs filesystems, so I would be interested in a solution as >> well. >> >>> My hardware setup contains a >>> - Intel Core i7 4770 >>> - Kernel 3.15.2-1-ARCH >>> - 32GB RAM >>> - dev 1-4 are 4TB Seagate ST4000DM000 (5900rpm) >>> - dev 5 is a 4TB Wstern Digital WDC WD40EFRX (5400rpm) >>> >>> Thanks in advance >>> >>> André-Sebastian Liebe >>> -------------------------------------------------------------------------------------------------- >>> >>> >>> # btrfs fi sh >>> Label: 'apc01_pool0' uuid: 066141c6-16ca-4a30-b55c-e606b90ad0fb >>> Total devices 5 FS bytes used 14.21TiB >>> devid 1 size 3.64TiB used 2.86TiB path /dev/sdd >>> devid 2 size 3.64TiB used 2.86TiB path /dev/sdc >>> devid 3 size 3.64TiB used 2.86TiB path /dev/sdf >>> devid 4 size 3.64TiB used 2.86TiB path /dev/sde >>> devid 5 size 3.64TiB used 2.88TiB path /dev/sdb >>> >>> Btrfs v3.14.2-dirty >>> >>> # btrfs fi df /data/pool0/ >>> Data, single: total=14.28TiB, used=14.19TiB >>> System, RAID1: total=8.00MiB, used=1.54MiB >>> Metadata, RAID1: total=26.00GiB, used=20.20GiB >>> unknown, single: total=512.00MiB, used=0.00 > This is interesting, I actually did some profiling of the mount timings > for a bunch of different configurations of 4 (identical other than > hardware age) 1TB Seagate disks. One of the arrangements I tested was > Data using single profile and Metadata/System using RAID1. Based on the > results I got, and what you are reporting, the mount time doesn't scale > linearly in proportion to the amount of storage space. > > You might want to try the RAID10 profile for Metadata, of the > configurations I tested, the fastest used Single for Data and RAID10 for > Metadata/System. Switching Metadata from raid1 to raid10 reduced mount times from roughly 120s to 38s! > > Also, based on the System chunk usage, I'm guessing that you have a LOT > of subvolumes/snapshots, and I do know that having very large (100+) > numbers of either does slow down the mount command (I don't think that > we cache subvolume information between mount invocations, so it has to > re-parse the system chunks for each individual mount). No, I had to remove the one and only snapshot to recover from a 'no space left on device' to regain metadata space (http://marc.merlins.org/perso/btrfs/post_2014-05-04_Fixing-Btrfs-Filesystem-Full-Problems.html) -- André-Sebastian Liebe -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
