I am seeing a performance issue on a Linux server using a QLA4010 to run
off of a OpenSolaris iSCSI target.
/dev/sda and /dev/sdb are both LUNs off of the same target, backed by zvols
from the same zpool. The fact
that /dev/sdb is getting SUCH better bandwidth is mind-boggling to me.
Some discrepancy between the two should probably be expected as /dev/sda is
the boot-device, but not this level...
contrast with what I am seeing on my test SAN. If it were just a load issue
I would expect both sda and sdb to be equally
slower relative to the test equivalent.
(some new-lines have been removed for the sake of legibility)
[EMAIL PROTECTED] ~]# for i in `seq 1 10`; do hdparm -t /dev/sda /dev/sdb;
sleep 1; done
/dev/sda: Timing buffered disk reads: 8 MB in 3.17 seconds =
2.52 MB/sec
/dev/sdb: Timing buffered disk reads: 138 MB in 3.15 seconds =
43.75 MB/sec
/dev/sda: Timing buffered disk reads: 4 MB in 3.88 seconds =
1.03 MB/sec
/dev/sdb: Timing buffered disk reads: 100 MB in 3.13 seconds =
31.93 MB/sec
/dev/sda: Timing buffered disk reads: 12 MB in 3.37 seconds =
3.56 MB/sec
/dev/sdb: Timing buffered disk reads: 84 MB in 3.04 seconds =
27.67 MB/sec
/dev/sda: Timing buffered disk reads: 4 MB in 3.07 seconds =
1.30 MB/sec
/dev/sdb: Timing buffered disk reads: 152 MB in 3.01 seconds =
50.50 MB/sec
/dev/sda: Timing buffered disk reads: 6 MB in 3.10 seconds =
1.94 MB/sec
/dev/sdb: Timing buffered disk reads: 168 MB in 3.02 seconds =
55.61 MB/sec
/dev/sda: Timing buffered disk reads: 8 MB in 5.29 seconds =
1.51 MB/sec
/dev/sdb: Timing buffered disk reads: 138 MB in 3.29 seconds =
41.89 MB/sec
/dev/sda: Timing buffered disk reads: 4 MB in 3.41 seconds =
1.17 MB/sec
/dev/sdb: Timing buffered disk reads: 122 MB in 3.06 seconds =
39.81 MB/sec
/dev/sda: Timing buffered disk reads: 12 MB in 3.14 seconds =
3.83 MB/sec
/dev/sdb: Timing buffered disk reads: 100 MB in 3.03 seconds =
33.05 MB/sec
/dev/sda: Timing buffered disk reads: 20 MB in 3.41 seconds =
5.86 MB/sec
/dev/sdb: Timing buffered disk reads: 108 MB in 3.03 seconds =
35.68 MB/sec
/dev/sda: Timing buffered disk reads: 22 MB in 3.25 seconds =
6.76 MB/sec
/dev/sdb: Timing buffered disk reads: 124 MB in 3.03 seconds =
40.94 MB/sec
[EMAIL PROTECTED] ~]# for i in `seq 1 10`; do hdparm -t /dev/sda /dev/sdb;
sleep 1; done
/dev/sda: Timing buffered disk reads: 152 MB in 3.03 seconds =
50.22 MB/sec;
/dev/sdb: Timing buffered disk reads: 174 MB in 3.01 seconds =
57.82 MB/sec;
/dev/sda: Timing buffered disk reads: 158 MB in 3.00 seconds =
52.63 MB/sec;
/dev/sdb: Timing buffered disk reads: 176 MB in 3.03 seconds =
58.01 MB/sec;
/dev/sda: Timing buffered disk reads: 164 MB in 3.00 seconds =
54.65 MB/sec;
/dev/sdb: Timing buffered disk reads: 176 MB in 3.03 seconds =
58.15 MB/sec;
/dev/sda: Timing buffered disk reads: 164 MB in 3.00 seconds =
54.62 MB/sec;
/dev/sdb: Timing buffered disk reads: 178 MB in 3.02 seconds =
58.93 MB/sec;
/dev/sda: Timing buffered disk reads: 174 MB in 3.02 seconds =
57.64 MB/sec;
/dev/sdb: Timing buffered disk reads: 182 MB in 3.02 seconds =
60.32 MB/sec;
/dev/sda: Timing buffered disk reads: 178 MB in 3.01 seconds =
59.04 MB/sec;
/dev/sdb: Timing buffered disk reads: 178 MB in 3.01 seconds =
59.07 MB/sec;
/dev/sda: Timing buffered disk reads: 174 MB in 3.03 seconds =
57.47 MB/sec;
/dev/sdb: Timing buffered disk reads: 176 MB in 3.01 seconds =
58.42 MB/sec;
/dev/sda: Timing buffered disk reads: 184 MB in 3.05 seconds =
60.27 MB/sec;
/dev/sdb: Timing buffered disk reads: 178 MB in 3.03 seconds =
58.80 MB/sec;
/dev/sda: Timing buffered disk reads: 178 MB in 3.03 seconds =
58.67 MB/sec;
/dev/sdb: Timing buffered disk reads: 176 MB in 3.01 seconds =
58.55 MB/sec;
/dev/sda: Timing buffered disk reads: 180 MB in 3.01 seconds =
59.76 MB/sec;
/dev/sdb: Timing buffered disk reads: 178 MB in 3.00 seconds =
59.25 MB/sec;
Andrew Hettinger
http://Prominic.NET || [EMAIL PROTECTED]
Tel: 866.339.3169 (toll free) -or- +1.217.356.2888 x.110 (int'l)
Fax: 866.372.3356 (toll free) -or- +1.217.356.3356 (int'l)
Mobile direct: 1.217.621.2540
CompTIA A+, CompTIA Network+, MCP
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