On Wednesday August 30, pwaldo@xxxxxxxxxxxxx wrote: > Hi all, > > I have an IMAP mail server where mail messages are stored on a RAID1 array. > The access on that array (/dev/md3) has seemed slow, so I did some investigating. > "iostat -x /dev/hd[bd] /dev/md3" shows this: > > avg-cpu: %user %nice %system %iowait %steal %idle > 14.34 47.03 13.99 19.64 0.00 5.00 > > Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util > hdb 1.05 34.88 35.48 2.60 1531.23 299.85 765.62 149.93 48.08 0.20 5.38 3.07 11.69 > hdd 0.70 34.83 41.08 2.65 963.12 299.85 481.56 149.93 28.88 0.15 3.49 1.65 7.24 > md3 0.00 0.00 78.31 36.98 2494.35 295.85 1247.18 147.93 24.20 0.00 0.00 0.00 0.00 > > > > > Here is my /proc/mdstat for md3: > > md3 : active raid1 hdb1[0] hdd1[1] > 12699264 blocks [2/2] [UU] > > > Observations: > - Stats for raw disks writes are similar > - Stats for reads on hdd are about half that of hdd Yes.... odd. There shouldn't be any bias to one drive or the other. When it scans for the best drive to use, it always starts from the last one that was used, so there should be no bias to one or the other. I assume they are identical drives? dd if=/dev/hdXX of=/dev/null bs=1024k count=1024 give similar speeds for each? NeilBrown -- VGER BF report: U 0.499857 - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
