Messages in this thread | | | Date | Mon, 12 Nov 2001 22:53:23 +0100 | From | Lionel Bouton <> | Subject | Re: File System Performance |
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> > > >I tried an experiment which puzzled me somwhat: > >> mount /xfs >> cd /xfs/lord/xfs-linux >> time tar cf /dev/null linux >> > >real 0m7.743s >user 0m0.510s >sys 0m1.380s > >>hdparm -t /dev/sda5 >> > >/dev/sda5: > Timing buffered disk reads: 64 MB in 3.76 seconds = 17.02 MB/sec > >>du -sk linux >> >173028 linux > >The tar got ~21 Mbytes/sec. > Things I'll check :
0/ rerun this test !!! 1/ is there cache on the scsi controler ? 2/ xfs data cached at mount ? (I don't believe so) 3/ "hdparm -t" is on crack. 4/ du reports a disk usage way ahead of files' sizes total (don't know xfs enough to estimate this propability) and tar won't read the whole "du -sk" data.
2/ "time mount /xfs" could help (if mount + tar times are below expected, this case can be eliminated). 3/ ask hdparm's maintener. 4/ tar, check tar size.
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