System

[vmsserbo]

One of our systems is periodically slow and a lot of users' sessions were hung followed by a connection host error/ timed out.

What could this be or cause this? Any ideas?

This machine is a :
a VAX 7000-620
Multiprocessing is ENABLED. Streamlined synchronization image loaded.

PRIMARY CPU = 00
Active CPUs: 00 01
Configured CPUs: 00 01

[Steven Schweda · Accepted solution]

There is an "OpenVMS Performance Management"
manual:

http://h71000.www7.hp.com/doc/73final/6491/6491pro.html


In general, start at:

http://h71000.www7.hp.com/doc/index.html

[Robert Gezelter]

Miles,

In my nearly 30 years of managing OpenVMS systems, I have seen innumerable situations where the symptom is initially described as "system is slow". The underlying causes of the behavior are, for all intents and purposes, as numerous as the performance incidents themselves.

Without a large amount of additional information, we are really "shooting in the dark" here. Steven's suggestion of starting with the Performance manual is a good one.

If the causes of the performance problem are not clear, it may be a good time to establish a relationship with someone with experience in performance and other aspects of system management (Obligatory disclosure of commercial interest: Yes, this is one of the services that is part of my consulting practice).

Alternatively, we are going to spend a lot of time on ITRC trying to randomly guess what MIGHT be wrong with the system (This is a bit along the lines of searching for a needle in the haystack).

As a starting point, does any performance data displayed by MONITOR correspond with the observed delays?

- Bob Gezelter, http://www.rlgsc.com

[Nigel Wright_1]

If you log on while this is happening - do you find the system slow? Do a mon proc/topcpu and see who is using cpu, bump your process priority up if you need to. Things I would initially look for are a lack of free disk space on the system disk or a process, possibly in a loop - effectivily hogging the cpu.

[Peter Zeiszler]

Do you have any data collection going on that would allow you to look at the different performace charts?

I am thinking like the old Polycenter data collector. I don't know if T4 is build around a VAX.

If you don't, then have you had an active window during the slowdown?
Set your priority to something like 6 (i.e. set proc/prio=6).
Then do a mon sys or mon proc/topc.
Look also for high memory/page swapping.

Is this problem occuring at a specific time or day of the week? Do you have any batch jobs for that time? Do you have backups run during that time? Is there a network load during that time?

Lots more information will be needed to be captured to get assistance. In the mean time you can use these suggestions to start trying to find the problem.

[comarow]

Miles my friend,

It's sort of like saying, my car is slow, why?

Log a call and get the performance cookbook. It will provide a checklist of things to look through.

Thanks,

Bob C

[Chinraj Rajasekaran]

Miles,

There could be many reasons for your system being slow and users can not login anymore.

Check these things when the system is slow.

1. First

$ moni process/topcpu

will tell you who is using more CPU. Identify the process and try to slowdown the process priority.

$ set process/id="XXXXXXX" prio=???

2. Check for any hardware related issues like.. particularly disks can really slow down the system performance.

monitor disk usage.

$ moni disk

will tell you which disk is used more...

$ show dev "disk" /file

will tell open files by the process in that disk.

May be application uses same disk for many processes waiting for resources may be..


regards
Raj

[henk van dorp]

Hi Miles,

Maybe another tip:

If the SWAPPER process consumes (relative) a (lot) of CPU , you might have a virtual memory problem.

In that case you might issue:
$ show memory/files
If there are negative numbers in it, you might run out of vitual memory (not nessesarilly).
This might indicate that some application has a memory leak.

hth

grtz

Henk