[Info-vax] RX2800 sporadic disk I/O slowdowns

[Richard Jordan]

On 11/5/24 10:32 AM, Volker Halle wrote:
> Am 18.10.2024 um 20:26 schrieb Richard Jordan:
> 
>> We periodically (sometimes steady once a week, but sometimes more 
>> frequent) one overnight batch job take much longer than normal to run. 
>> Normal runtime about 30-35 minutes will take 4.5 - 6.5 hours.  Several 
>> images called by that job all run much slower than normal.  At the end 
>> the overall CPU and I/O counts are very close between a normal and a 
>> long job.
> 
> If 'overall CPU and I/O counts' are about the same, please re-consider 
> my advice to run T4. Look at the disk response times and I/O queue 
> length and compare a 'good' and a 'slow' run.
> 
> If 'the problem' would be somewhere in the disk IO sub-system, changing 
> RMS buffers will only 'muddy the waters'.
> 
> Volker.

Volker,
      we are getting T4 running on the backup server to re-learn it; its 
been more than 10 years since we played with it on another box.

      I have monitor running and have been checking the I/O rates and 
queue lengths during the 30+ minute runs and the multi-hour runs, and 
the only diffs there are the overall I/O rates to the two disks are much 
lower on the long runs than on the normal short ones.

      But we'll try T4 and see what it shows once I'm happy with it on 
the backup server.

      This stuff is interfering with getting the 8.4-2L3 testing done so 
we can upgrade the production server asap.