question about dump performance on a snapshot
Don Bowman
don at sandvine.com
Mon Mar 29 14:02:55 PST 2004
How long should it take to run 'dump' on a snapshot?
I have a 6-disk raid 5 with 15K RPM scsi disk, so quite
fast. It is 300GB in size, with 20% occupied. There
are ~6000 files on this filesystem, all postgresql.
I stopped postgresql, did a file system snapshot, and
restarted postgresql. I then commenced a dump on the
snap as below:
dump -0 -a -C 32 -f $dumpfile -u $snapfile
dumpfile and snapfile are both on the same filesystem.
for the last 35 minutes, the size of the dump file has
not gone up, and dump is taking 0% cpu:
# dump -0 -a -C 32 -f $backupfile -u $outfile
DUMP: Date of this level 0 dump: Mon Mar 29 16:32:25 2004
DUMP: Date of last level 0 dump: the epoch
DUMP: Dumping /data/snapshot/snap.1 to /data/backup/dump.1
DUMP: mapping (Pass I) [regular files]
DUMP: Cache 32 MB, blocksize = 65536
DUMP: mapping (Pass II) [directories]
DUMP: estimated 59867851 tape blocks.
DUMP: dumping (Pass III) [directories]
DUMP: dumping (Pass IV) [regular files]
load: 0.00 cmd: dump 39347 [runnable] 1.20u 5.70s 0% 48616k
# ps -wwax |grep dump
39584 p1 L+ 0:00.00 grep dump
39336 d0 I+ 0:01.61 dump -0 -a -C 32 -f /data/backup/dump.1 -u
/data/snapshot/snap.1 (dump)
39347 d0 I+ 0:06.90 dump: /data/snapshot/snap.1: pass 4: 0.94% done,
finished in 1:34 (dump)
39348 d0 I+ 0:08.18 dump -0 -a -C 32 -f /data/backup/dump.1 -u
/data/snapshot/snap.1 (dump)
39349 d0 I+ 0:08.18 dump -0 -a -C 32 -f /data/backup/dump.1 -u
/data/snapshot/snap.1 (dump)
39350 d0 I+ 0:08.26 dump -0 -a -C 32 -f /data/backup/dump.1 -u
/data/snapshot/snap.1 (dump)
Although the dump always indicates it is 'runnable' when i
hit ^T, it doesn't run, and doesn't consume any cpu.
The machine is idle.
machine is running current cvsup from march 21 on a dual
xeon 2.8 with asr raid controller.
# tunefs -p /dev/da0s1e
tunefs: ACLs: (-a) disabled
tunefs: MAC multilabel: (-l) disabled
tunefs: soft updates: (-n) enabled
tunefs: maximum blocks per file in a cylinder group: (-e) 2048
tunefs: average file size: (-f) 16384
tunefs: average number of files in a directory: (-s) 64
tunefs: minimum percentage of free space: (-m) 8%
tunefs: optimization preference: (-o) time
tunefs: volume label: (-L)
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