Legacy HDS Forums

IOPS vs MB / second

Discussion created by Legacy HDS Forums on Feb 8, 2007
Latest reply on Feb 20, 2007 by Legacy HDS Forums

Originally posted by: Chris Tatro

Hi everyone, I used a program called sqlio.exe from Microsoft to test SQL I/O on my SAN. And I?m wondering if someone can help me interpret the readings.
The chart can be read like this, on the left hand side of the first column it reads ?4kb random write IO? I set sqlio.exe to write randomly to the disk which was formatted in NTFS 8kb cluster sizes on a RAID 5 array.

I am wondering if higher IOs per second are better then MB/s second?
If you compare 8kb random write IO which is 1338.84 IOPS and 8kb random write MB/s is 10.44MB / second to 64kb random write IO which is 480.92 IOPS and 64kb random write MB/s is 30.04MB / second.
As you can see NTFS formatted in 8kb delivers higher IOs / second but delivers less MB / second then a file system formatted in 64kb clusters. Which will deliver better performance 8kb or 64kb NTFS clusters based on this data? The load on the system is roughly 60% random reads, 38% sequential reads, 2% write.

NTFS cluster size 8kb     
4 Separate LUNS / RAID5 6 disks per LUN
4kb random write IO                   1382.6
4kb random write MB/s     5.4
4kb random read IO                     3671.2
4kb random read MB/s     14.32
4kb sequential write IO     31396.72
4kb sequential write MB/s     122.64
4kb sequential read IO     69606.2
4kb sequential read MB/s     271.88
8kb random write IO                     1338.84
8kb random write MB/s     10.44
8kb random read IO                     3469.36
8kb random read MB/s     27.08
8kb sequential write IO     25640
8kb sequential write MB/s     200.28
8kb sequential read IO     37097.76
8kb sequential read MB/s     289.8
64kb random write IO                     480.92
64kb random write MB/s     30.04
64kb random read IO                     1954.44
64kb random read MB/s     122.12
64kb sequential write IO     6310.32
64kb sequential write MB/s     394.36
64kb sequential read IO     7867.44
64kb sequential read MB/s     491.68

NTFS cluster size 64kb     
4 Separate LUNS / RAID5 6 disks per LUN
4kb random write IO                     1405.76
4kb random write MB/s     5.48
4kb random read IO                     3784
4kb random read MB/s     14.76
4kb sequential write IO     24114.4
4kb sequential write MB/s     94.16
4kb sequential read IO               72607.96
4kb sequential read MB/s     283.6
8kb random write IO                     1236.68
8kb random write MB/s     9.64
8kb random read IO                     3494.08
8kb random read MB/s     27.28
8kb sequential write IO     20072.4
8kb sequential write MB/s     156.8
8kb sequential read IO     33650.52
8kb sequential read MB/s     262.88
64kb random write IO                     492.44
64kb random write MB/s     30.76
64kb random read IO                     1994.52
64kb random read MB/s     124.64
64kb sequential write IO     5921.28
64kb sequential write MB/s     370.08
64kb sequential read IO     7652.24
64kb sequential read MB/s     478.24