read slower than write on "mv"?
This is not XFS specific, I see it on every filesys. I do a "mv . /newlocation" and see this with iostat:
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-
sz avgqu-sz await svctm %util
xvdb 608,60 2,60 25967,20 102,40 85,31 5,37
8,77 1,58 96,72
xvdg 0,00 608,60 0,00 26532,10 87,19 7,55
12,41 0,12 7,44
Reading takes 97% I/O time, writing 7%. This is on the same raidset, but I see the same when copying between two different single disks also. Or is it just an effect of write caching that writes look faster than reads?
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Quoted 10 lines · Michael Monnerie
This is not XFS specific, I see it on every filesys. I do a "mv . /newlocation" and see this with iostat:
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-
sz avgqu-sz await svctm %util
xvdb 608,60 2,60 25967,20 102,40 85,31 5,37
8,77 1,58 96,72
xvdg 0,00 608,60 0,00 26532,10 87,19 7,55
12,41 0,12 7,44
Quoted 4 lines
Reading takes 97% I/O time, writing 7%. This is on the same raidset, but I see the same when copying between two different single disks also. Or is it just an effect of write caching that writes look faster than reads?
Yes, just an effect of write caching hiding IO latency.
Cheers,
Dave.
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Dave Chinner [email protected] _______________________________________________ xfs mailing list [email protected] http://oss.sgi.com/mailman/listinfo/xfs