Quoting Dmitry Morozovsky <[email protected]>:
Well, I can see at least one rather big problem with bgfsck (or with snapshots to be more precise): inappropriate time of file system lock on snapshot creation. On not-too-big 300G ufs2 not-too-heavy loaded snapshot creation time is 20+ minutes, and 5+ from that file system blocked even on reads. This looks unacceptable for me for any real use.
The snapshot time depends heavily on the I/O throughput of your disk subsystem. On a several year old system with 5 x 72GB 15KRPM U320 SCSI drives in a RAID5 array, a fairly well loaded 260GB filesystem (90GB used, 354K out of 8M inodes used, and several hundred MB to a GB of changes per day) completes a snapshot in exactly 2 minutes. 2 minutes is still too long to be blocking I/O in the middle of the day when it is being actively used, so I just take 1 snapshot per day while it is idle. I would love to put ZFS on this system so that I could have finer grained snapshots, but I need user quota support which our ZFS currently lacks.
-- Chris Dillon - NetEng/SysAdm Reeds Spring R-IV School District Technology Department 175 Elementary Rd. Reeds Spring, MO 65737 Voice: 417-272-8266 Fax: 417-272-0015 _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[email protected]"
