Jeff Breidenbach: > I married an Intel X25-E solid state drive to a traditional disk drive > using aufs1. Cached directory listing seems particularly slow. Would > I get dramatically better performance for this case with aufs2? Or is > there a different union mount technology that I should be considering? > The underlying filesystems are XFS, with many files per directory.
In general aufs2 is smaller and faster than aufs1, but I don't know how much aufs2 is better for you. It may not be fast enough because of millions of files under a single dir. If your system has enough memory to cache all the entries in /mnt/ssd, /mnt/rotating-rust, and /mnt/aufs (total will be about 3 millions), then the aufs mount option 'rdcache=<sec>' may help you. Try setting rdcache=60 or rdcache=90. I hope it will be better a little. But I guess enlarging the aufs internal hash table is more effective. If you really need such enhancement, let me know. ---------------------------------------------------------------------- > Sorry, I just noticed that a lot of detailed system information is > requested with problem reports. Here's the real data. /data4 is the Thank you. > ~# dmesg | grep aufs > [2424740.994311] aufs 20080128 Please update aufs. It is VERY OLD (more than a year). > [2428345.252742] aufs au_dtime_revert:158:detect_spam.py[15744]: > restoring timestamps failed(-1). ignored That is not good, but we can endure... > [2520586.263728] [<ffffffff883e9149>] :aufs:au_kzrealloc+0x39/0x60 > [2520586.263736] [<ffffffff883e383d>] :aufs:au_vdir_init+0x30d/0x4c0 > [2520586.263743] [<ffffffff883e1b15>] :aufs:fbstart+0x5/0x10 > [2520586.263750] [<ffffffff883e03d6>] > :aufs:au_reval_and_lock_finfo+0x3a6/0x6e0 > [2520586.263767] [<ffffffff883e1f52>] :aufs:aufs_readdir+0x82/0x130 > [2520659.915168] [<ffffffff883e9149>] :aufs:au_kzrealloc+0x39/0x60 > [2520659.915178] [<ffffffff883e383d>] :aufs:au_vdir_init+0x30d/0x4c0 > [2520659.915187] [<ffffffff883e1b15>] :aufs:fbstart+0x5/0x10 > [2520659.915194] [<ffffffff883e03d6>] > :aufs:au_reval_and_lock_finfo+0x3a6/0x6e0 > [2520659.915214] [<ffffffff883e1f52>] :aufs:aufs_readdir+0x82/0x130 That is BAD. I am afraid you met kernel oops or something, and it is the main reason of your slowness. If you can, please show me the full message. > # cat /proc/version > Linux version 2.6.24-8-server (bui...@yellow) (gcc version 4.2.3 > (Ubuntu 4.2.3-1ubuntu2)) #1 SMP Thu Feb 14 20:42:20 UTC 2008 Generally aufs in ubuntu doesn't work well because the aufs module in ubuntu is too old. > **/sys/fs/aufs/ffff81075fd89800/xino** > 17600x4096 8998912 > 0: 1, 192936x4096 2024912640 > 1: 1, 4219552x4096 30303827200 These large files are created on your first writable branch (/data4/.aufs.xino). Is the capacity enough? J. R. Okajima ------------------------------------------------------------------------------
