I'm using rsnapshot (http://rsnapshot.org/) to automatically backup my root filesystem (btrfs) to a second harddrive running ext4. Rsnapshot uses rsync and a massive amount of hard links to keep multiple backups instantly available. It seems that the sheer number of hard links overwhelms ext4 and results in problems that require manual fsck.ext4 runs to bring the fs back to normal. For example this is output from fsck.ext4: Problem in HTREE directory inode <some number> ... node <increasing number> has invalid depth (2) ... node <increasing number> has bad mxhash ... node <increasing number> not referenced This output is repeated ad nauseam while <increasing number> increases at each round. The bug is very simple to reproduce here. Just run rsnapshot several times per day and you will eventually hit the problem. # tune2fs -l /dev/sda1 tune2fs 1.41.9 (22-Aug-2009) Filesystem volume name: <none> Last mounted on: /var Filesystem UUID: 46e99ee2-615d-4ce8-9641-a8c0118fdaa3 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize Filesystem flags: signed_directory_hash Default mount options: (none) Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 6545408 Block count: 26165860 Reserved block count: 1308292 Free blocks: 18575443 Free inodes: 5761975 First block: 0 Block size: 4096 Fragment size: 4096 Reserved GDT blocks: 1017 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 8192 Inode blocks per group: 512 RAID stride: 32732 Flex block group size: 16 Filesystem created: Mon Jun 8 12:08:51 2009 Last mount time: Wed Sep 9 15:03:04 2009 Last write time: Wed Sep 9 15:03:04 2009 Mount count: 1 Maximum mount count: 5 Last checked: Wed Sep 9 15:02:21 2009 Check interval: 15552000 (6 months) Next check after: Mon Mar 8 14:02:21 2010 Lifetime writes: 434 GB Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 256 Required extra isize: 28 Desired extra isize: 28 Journal inode: 8 Default directory hash: half_md4 Directory Hash Seed: 28e527ba-4f7f-4588-a956-c87042f237e6 Journal backup: inode blocks This machine is running the latest git kernel (2.6.31-rc9). -- Markus -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
