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question asked: Oct 16 '13, 8:10 a.m.
question was seen: 5,536 times
last updated: Oct 18 '13, 2:04 a.m.

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RTC 3.0.1. with DB2 on Windows: High disk I/O on vstr_32k table space

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Ulf Buchner (318●22●13) | asked Oct 16 '13, 8:10 a.m.
Hi all,

For a while now we are running RTC 3.0.1. with DB2 LUW 9.7 on Windows Server 2008. At some times we encounter quite high disk I/O (about 100MBit/s) on the vstr_32k table space, which seems to impact performance in a negative way. I've increased the LOGBUFSZ parameter to as much as 64k, but nothing seems to help. Is there another way to decrease the disk I/O?

Thanks!

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Donald Nong (14.5k●6●14) | answered Oct 16 '13, 9:04 p.m.
Apart from increasing the in memory cache, I doubt that you can do much to decrease the disk I/O. When the data are requested, the database need to read from somewhere - memory or the disk (physical file).
The vstr_32k table space contains the RIDW module, which I believe will be heavily utilized when some reports are run.
Ulf Buchner selected this answer as the correct answer
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Ulf Buchner commented Oct 17 '13, 4:41 a.m.

Donald, I noticed that the "Task Delay" property in the Reports section of the Advanced Server Properties is set to 500. The hint on this properties says it shouldn't be changed. Would it help to increase this to 86400 (once a day)?

Donald Nong commented Oct 17 '13, 8:32 p.m.

Is 500 the default value? I don't have a RTC 3.0.1 environment to check now but the value is quite interesting. The below post has some discussion about this property.
https://jazz.net/forum/questions/111564/delay-updating-charts-with-current-data

Ulf Buchner commented Oct 18 '13, 2:04 a.m.

Yes, 500 is the default. I changed it yesterday and currently (we just started our working day here in the Netherlands) there is no major disk activity on the vstr_32k.1 file. Let's see what happens during the day.

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Ulf Buchner (318●22●13) | answered Oct 17 '13, 4:11 a.m.
Thanks Donald. I expected this answer, of course. Normally I would place the table space on a separate disk or even better a SSD (as advised by IBM), but as we are running on our company VMWare host this is not possible.
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Donald Nong commented Oct 17 '13, 8:37 p.m.

I believe you can assign a dedicated physical disk to a VMWare machine is you really want to. Or you can upgrade the storage system of the VMWare host to some form of RAID.

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