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I tried measuring virtual disk performance using bonnie++.

Case 1 result :

Using uid:0, gid:0.
Writing intelligently...done
Rewriting...done
Reading intelligently...done
start 'em...done...done...done...
Version 1.03e       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
TEST_IO          1G           91486  10 31793   2           71461   2 166.0   1
TEST_IO,1G,,,91486,10,31793,2,,,71461,2,166.0,1,,,,,,,,,,,,,

Case 2 Result :

Using uid:0, gid:0.
Writing intelligently...done
Rewriting...done
Reading intelligently...done
start 'em...done...done...done...
Version 1.03e       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
TEST_DP_IO       1G           104599  22 40353   6           99579   6 163.6   0
TEST_DP_IO,1G,,,104599,22,40353,6,,,99579,6,163.6,0,,,,,,,,,,,,,

In case 2 , I get better performance (correct me If I am wrong).

So I interpret results in this way:

Case 1 : 

91486 = 89 MBps
31793 = 31.04 MBps
71461 = 69.7 MBps
166 IOPS

Case 2:

104599 = 102 MBps Write
40353  = 39.4 MBps Re-Write
99579 = 97.2 Read

163.6 IOPS

As you can see, write, Re-Write, Read performance is better in Case 2 except IOPS?? Should IOPs numbers must be greater than Case 1 ?? Is it valid to have lesser IOPS and more performance in Write, Read. ??

Thx

kumar
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  • Could you add some context here? What are you trying to measure, and what is the storage you're testing? – Basil Apr 13 '14 at 15:49
  • What are you trying to measure - Virtual disk performance in qemu-kvm based guest , storage - Virtual disk from inside disk( SATA physical disk). OS - RHEL, Guest OS - RHEL – kumar Apr 14 '14 at 06:07
  • My basic intention of question is Can IOPS be lesser than Write/ Read performance ?? – kumar Apr 14 '14 at 06:08
  • Do you know what IOPS are? It's the number of IOs done per second. Read/write performance can be measured in IOPS, so what you asked is like asking "can KM/h be less than speed". – Basil Apr 14 '14 at 10:00
  • Do you meant to say what MDMarra said is wrong?? – kumar Apr 14 '14 at 10:08
  • not at all, but it's also not an answer to your question, because your questions is not logically consistent. – Basil Apr 15 '14 at 11:58

1 Answers1

3

IOPS are important for non-sequential IO.
Throughout is important for sequential IO.

It's possible (and likely) to see what you're seeing depending on the workloads.

MDMarra
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