topic Re: Physical_ii_buffers kernel parameter setting in Operating System - HP-UX

Physical_ii_buffers kernel parameter setting

karloliver — Fri, 28 Oct 2011 01:21:56 GMT

Help please

do you set this parameter in

B.11.23/ U 9000/800

what doe the auto mean ?

We have 2 system set up the same 1 processor 4 gig memory each. san disk used.

on 1 system db job takes 46 minutes and on the other it takes 2h 28 min.

THe only difference I can see is in the kernel parameters

on fast system

set at physical_io_buffers 1280 Default Auto

on slow systemphysical_io_buffers 1024 Default Auto

sar shows high %wio on slow system

I have no idea of san specs. The systems are using different sans

would physical_io_buffers make much difference

Re: Physical_ii_buffers kernel parameter setting

Stephan. — Fri, 28 Oct 2011 10:53:54 GMT

>much difference?

>what does the auto mean?

# kctune -v physical_io_buffers
Tunable             physical_io_buffers
Description         Number of buffers (512 bytes each) for physical I/O operations
Module              vm
Current Value       768 [Default]
Value at Next Boot  0 [Default]
Value at Last Boot  768
Default Value       768
Constraints         physical_io_buffers == 0 or physical_io_buffers >= 384
                    physical_io_buffers <= 65535
Can Change          Automatic Tuning Enabled

>The systems are using different sans

Here you go ...

Re: Physical_ii_buffers kernel parameter setting

karloliver — Mon, 31 Oct 2011 21:51:13 GMT

There is a big difference

on fast system db update takes 46 mins slow system 2h .26 mins

on fast system db restore takes 2 hours on slow system it takes 7H 32 mins - restore is from disk

The databases are the same size db configuration are the same . DB is informix

Re: Physical_ii_buffers kernel parameter setting

Stephan. — Tue, 01 Nov 2011 06:50:02 GMT

Still the same ... check the SAN ...

- Hardware is the same

- Software is the same

- Configuration is the same

then

- the SAN is the point to check.

Especially if you say the systems use different SANs and you don't know anything about it.

Changing the kernel parameter will not fix this.