topic Re: ioscan performance in Operating System - HP-UX

ioscan performance

siaemic — Wed, 26 Mar 2003 15:23:11 GMT

We are experiences a problem using rpc funcions inside a C program. Our application seems to have problems only on B2000,B2600 workstations. We received a suggestion to execute "ioscan -fnC disk" command on ws where our application runs and on a ws where our application fails. On last ws (ko) ioscan takes 45 sec. while on first ws (ok) it takes 5 sec. Can these two events be related ? Is it a problem of some hp patch ?

Re: ioscan performance

Pete Randall — Wed, 26 Mar 2003 15:28:45 GMT

Are the two workstations the same verion of the O/S? Ioscan changed behaviour between 10.20 and 11.0 (I think). It now looks at all the physical devices. You can force it to just scan the kernel by using the -k option. If both ws are the same version, try the -k option and see what that results in.

Pete

Re: ioscan performance

Steve Steel — Wed, 26 Mar 2003 15:41:34 GMT

Hi

What is your latest ioscan patch

PHCO_27818 s700_800 11.00 ioscan(1M) cumulative patch

records performance problems in certain setups.

Steve Steel

Re: ioscan performance

siaemic — Wed, 26 Mar 2003 16:08:39 GMT

Pete,

Both ws are unix 11.00.
I perform ioscan -k on both ws and it was immediate to return.

Steve,

Patch PHCO_27818 is not installed on both ws.

Re: ioscan performance

Pete Randall — Wed, 26 Mar 2003 16:13:28 GMT

Do the workstations differ in the amount of devices reported by ioscan? What I mean is, does ioscan have more legitimate work to do on one than it does on the other?

Pete

Re: ioscan performance

siaemic — Wed, 26 Mar 2003 16:27:27 GMT

Pete,

no just one disk and a CD device on both ws

Re: ioscan performance

Steve Labar — Wed, 26 Mar 2003 18:55:24 GMT

Sometimes missing or incorrect SCSI terminators will cause performance problems. Verify you have the correct terminators connected to each ws.

Good Luck.

Steve

Re: ioscan performance

Eugeny Brychkov — Wed, 26 Mar 2003 22:05:34 GMT

I fully agree with Steve. Terminator or other SCSI bus problems (like misbehaving device) is leading to ioscan working too long time and somethmes even hangs. Unfortunately there're no external SCSI connectors to terminate in B2000... maybe B2600 has them? Maybe you have addon SCSI card installed with bus terminated improperly? Try disconnecting all external devices (if any, exluding, of course, terminal, keyboard and mouse :o) )
Eugeny

Re: ioscan performance

Bill Hassell — Thu, 27 Mar 2003 00:22:06 GMT

I would change your application to add the -k option. It will always run instantly since it does not query every I/O channel and device on the system. Unless you are (dangerously) adding devices with power on, ioscan -kfnC disk will be just as valid as without -k, but will complete in a second or two. The -k tells ioscan to read all the info from kernel memory.

Re: ioscan performance

T G Manikandan — Thu, 27 Mar 2003 03:29:49 GMT

ioscan taking a long time might be that some device is not responding.

check your /var/adm/syslog/syslog.log

for any scsi lbolt errors.

If that is the case then check up your scsi cabling and termination

Revert