On 08/31/2017 12:43 PM, Marco Lorenzo Crociani wrote: > Hi, > this 37T filesystem took some times to mount. It has 47 > subvolumes/snapshots and is mounted with > noatime,compress=zlib,space_cache. Is it normal, due to its size?
Yes, unfortunately it is. It depends on the size of the metadata extent tree. During mount, the BLOCK_GROUP_ITEM objects are loaded from that tree. They're scattered all around, causing a lot of random reads when your disk cache is still ice cold. > # time mount /data/R6HW > > real 1m32.383s > user 0m0.000s > sys 0m1.348s > > # time umount /data/R6HW > > real 0m2.562s > user 0m0.000s > sys 0m0.466s > > > # df -h > /dev/sdo 37T 20T 18T 53% /data/R6HW > > # btrfs fi df /data/R6HW/ > Data, single: total=19.12TiB, used=19.12TiB > System, DUP: total=8.00MiB, used=2.05MiB > Metadata, DUP: total=37.50GiB, used=36.52GiB > GlobalReserve, single: total=512.00MiB, used=0.00B > > # btrfs device usage /data/R6HW/ > /dev/sdo, ID: 1 > Device size: 36.38TiB > Device slack: 0.00B > Data,single: 19.12TiB > Metadata,DUP: 75.00GiB > System,DUP: 16.00MiB > Unallocated: 17.18TiB -- Hans van Kranenburg -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
