You can calculate the rate which your queue manager on z/OS is logging data as follows.

In the output from SupportPac MP1B there is a section for the log data.

For example

MVCA,MQPB,2013/08/28,05:42:49,VRM:710,

..

MVCA,MQPB,2013/08/28,05:43:46,VRM:710,

Wait for buffers(should be 0): 0

Total Number of pages written: **579460**

Total Number of write requests: 458698

Pages written per I/O: 1

Total number of read requests: 0

The interval between the two records is 57 seconds. ( 05:42:49 to 05:43:46).

The number of 4KB pages written in this time is 579460.

So there were 579460 *4096 bytes written to the log.

This is 579460* 4096 /(1024 *1024) MB = 579460 /(256).

The rate is then 579460 /(256 * 57) = 39 MB/Second

or using calculator: calculate *Number of pages writen*/256, then divide by the duration.

At Hursley we typically get 150-180 MB/Second

If you are using dual logging then there will this amount of data to each log.

__How can I tell my average log I/O response time?__

In the above data we have 458698 I/Os were written in 57 seconds. This is for dual logs, so there are half this number per log.

The number of I/O a second is (458698/2)/57 = 4023. If the log was busy all the time then the response time is 1/4023 = 0.000248 = 0.2 ms. If the log was not busy all of the time, then the estimate of the log response rate will be too large.

The log response time depends on the amount of data written per log request. If there are one or two pages per I/O then we get log response time under 0.5 ms. This is typical for DASD which is not mirrored

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