From: Holger.VanKoll@SWISSCOM.COM
Date: Tue Nov 12 2002 - 14:31:20 EST
Hello,
I am doing some benchmarking of my internal hdisks (dd </dev/hdisk0-3
>/dev/null bs=256k); Aix 5.1.
Topas tells
Readch 183.3M
Writech 183.3M
So 183 Megabyte per second are read (from disk) and written (to
/dev/null).
Thats also what I roughly measure using date ; dd ... ; date.
The disc-statistic is what I dont understand:
Disk Busy% KBPS TPS KB-Read KB-Writ
hdisk0 100.3 458.5K 114.6K 458.5K 0
hdisk1 100.3 453.9K 113.5K 453.9K 0
hdisk3 100.3 455.6K 113.9K 455.6K 0
hdisk2 99.3 455.8K 114.0K 455.8K 0
Thats 458.5 Megabyte per disc per second. Way too high transferrate (10
x times too much).
Or am I misinterpreting?
Furthermore I wonder why I see Readch at 180M (as before) and Writech at
0 (or other way round) sometimes at higher monitoring-intervals.
Iostat 10 gives
Disks: % tm_act Kbps tps Kb_read Kb_wrtn
hdisk0 99.8 46903.1 11725.7 469148 0
hdisk3 99.9 46632.3 11658.1 466440 0
hdisk2 100.0 46906.3 11726.5 469180 0
hdisk1 100.0 46617.5 11654.5 466292 0
Looks correct (184M/sec).
I only have one aix5.1 node here. Can anybody confirm that topas gives
10 x too much disk-transfer-numbers?
Regards,
Holger
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