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

slow ioscan

Paul_481 — Wed, 25 May 2005 22:16:28 GMT

Hi,

We have a SAN with 6 servers, 1 MSL tape library and 1 EVA5000. We are using zoning with the following configuration.

zone1: servera,eva,msl 2 FCA card
zone2: serverb,eva,msl 2 FCA card
zone3: serverc,eva,msl 2 FCA card
zone4: serverd,eva,msl 2 FCA card
zone5: servere,eva,msl 2 FCA card
zone6: serverf,eva,msl 1 FCA card

Our problem is when running ioscan on serverf, it is very slow compared to the other server.

This server is the Data Protector Server and we plan to use it as a business copy mount point for the other servers.

Sometimes when I try to run ioscan I get a SCAN result on the status instead of claimed.

The most obvious reason could be because of only 1 FCA card attached , or is it?

Regards,
Paul

Re: slow ioscan

Devesh Pant_1 — Wed, 25 May 2005 22:55:01 GMT

Paul,
What ioscan connamd are you running
do an ioscan -fn and after that just try to see the device you want to look at
like ioscan -funC fc
or ioscan -funC disk
or ioscan -funC tape
I can see that the serverf has only one HBA.
What multipathing software are you using on the other servers that have 2 HBAs?
I would say if you can see all the LUNs, there should be no problem in mounting business copies and doing backups on this server.

Devesh

Re: slow ioscan

Paul_481 — Wed, 25 May 2005 23:06:49 GMT

We use securepath to all servers. Any ioscan command is very slow to resolve compare to to other server.

It eventually able to detect the LUNs but my main problem is it is very slow.

Regards,
Paul

Re: slow ioscan

Ermin Borovac — Thu, 26 May 2005 00:53:55 GMT

If you see software state as "SCAN" it means that there is another instance of ioscan running on the system. Maybe one of the daemons (diagnostics) is firing them off. Check with ps to see if you can catch it in act.

Re: slow ioscan

Cem Tugrul — Thu, 26 May 2005 08:51:30 GMT

Paul,

i think having only a 1 HBA on Data Protector
server is not good option because when
you want to take bck of servers (more than 1
srv at the same time) so the I/O read-writes
runs over a single HBA so this makes your back time long...
On the other hand,Could you run the command,
spmgr display on this backup srv and
try to check ;
Load Balance: On Auto-restore: On Balance Policy: Round Robin

Good luck,

Re: slow ioscan

Marlou Everson — Fri, 27 May 2005 15:17:40 GMT

Paul,

We also had a problem with a slow ioscan. By slow, I mean an ioscan on one system that normally would take 5 seconds now took 9 minutes. We know when it started. We upgraded switch firmware on one of our fabrics. Only some systems were slow and not others. There was nothing logical why some were fast and others were slow. HP worked on the problem too. Last Monday, ioscans on all systems were fast again.

What we did learn was that the SCAN state would happen if another ioscan was running and that SAM could be the culprit. It appears to launch an ioscan in the background and the ioscan is still running even after you exit SAM, which is likely to happen if ioscan is taking 10 minutes instead of 5 seconds.

Marlou

Re: slow ioscan

Bharat Katkar — Fri, 27 May 2005 15:46:27 GMT

Hi Paul,
Ioscan is taking time means the I/O is going in loop for some time. I would check following things:

1. Harware Paths to the I/O devices (Arrays,Tapes,disk etc.) are stable.
2. Proper Device Files are present on the System.
3. All necessary patches are applied to the System

Regards,

Re: slow ioscan

Devesh Pant_1 — Fri, 27 May 2005 17:41:07 GMT

Paul,
could you post the output of ioscan here ?

thanks
Devesh

Re: slow ioscan

Bill Hassell — Fri, 27 May 2005 20:31:48 GMT

ioscan is working at a very low level,sing the driver to probe every possible connection on every card. The difference may be a possible hardware or firmware problem so I would poke around syslog and other diagnostic tools for possible problems.

But there is no reason to run ioscan in a full-probe mode unless you have just added new devices while the system is running. If you use the -k option, you'll get instant results no matter how big your system might be.