topic Re: Session Slowdowns after noon times? in Operating System - OpenVMS

Session Slowdowns after noon times?

andy200 — Wed, 28 Mar 2007 11:52:52 GMT

Hello there -

I was wondering why is it around after noon time my
users are complaining that their sessions are being
very very slow to load the various programs connecting
to a OpenVMS 7.1-2 Alpha server.

Is the Alpha servers are prone to overheating and
thats why my end users are having slow sessions?

Tnank you
Andy

Re: Session Slowdowns after noon times?

EdgarZamora_1 — Wed, 28 Mar 2007 12:29:28 GMT

You will need to be more specific. What do you mean by sessions (are your users interactively logged into the VMS system, or are these client/server type apps)? Are there more users after noon? Are you sure it's not the network? Do you do any performance data collection on the VMS system. I would recommend T4 (download from website), or actually you could just start with using the MONITOR utility. Do a HELP MONITOR from DCL to get mroe info on the MONITOR utility or read the OpenVMS documentation.

Overheating Alphaservers will not cause you slow sessions. They might cause you no sessions at all, instead.

Re: Session Slowdowns after noon times?

Robert Gezelter — Wed, 28 Mar 2007 15:11:43 GMT

Andy,

Overheating is unlikely to be the issue.

The correct way to examine this issue is, as has been suggested, to gather utilization data and look at the workload.

In nearly 30 years of doing performance tuning as part of my consulting practice, I can safely say that the most common reason for a "after lunch" slowdown is the number of people who come back from lunch and immediately start workiing. In the morning, there is often more of a spread.

The answer to all performance issues is to do the underlying science thoroughly. That way, one finds a solid answer.

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

Re: Session Slowdowns after noon times?

Steven Schweda — Wed, 28 Mar 2007 19:06:08 GMT

There's also a whole "OpenVMS Performance
Management" manual available at the usual
place. (VMS V7.1-2 is a bit older than the
manual, but much/most of it should hold.)

http://h71000.www7.hp.com/

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

Oldest:
http://h71000.www7.hp.com/doc/os73_index.html

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

Re: Session Slowdowns after noon times?

Martin Hughes — Wed, 28 Mar 2007 19:54:29 GMT

To get help in diagnosing a performance issue in a forum such as this, you really need the skills to be able to at least partially diagnose the problem yourself. There are a vast number of issues that can cause performance slows; it could be network, system, application, and within each of these broad areas there are countless possible issues that can cause performance slowdown.

Your best bet would be to enlist the help of a VMS specialist to diagnose the problem.

Re: Session Slowdowns after noon times?

andy200 — Wed, 28 Mar 2007 23:40:01 GMT

Users are connecting to VMS systems from their WIndows machines using the IBM Personal Comm. telnet client.

For example:

If were to select a command from the menu option screen, it says LOADING....and this usually takes about 5 to 10 seconds to load to the other screen. Another example would be whenever I cancel an order after I press ENTER, it just takes a long time to clear everything from the screen.

NOTE> We are using a CAPTIVE logon enviroment and not the DCL access commands.

But why is it that around noon time it slows down??

Re: Session Slowdowns after noon times?

Steven Schweda — Wed, 28 Mar 2007 23:44:50 GMT

> But why is it that around noon time it
> slows down??

It may be that something different happens
on your system, on your network, or with your
users at about that time. How do you expect
anyone with no access to your system to guess
what's happening there?

Try calling a Psychic Hot-Line?

Re: Session Slowdowns after noon times?

Robert Gezelter — Thu, 29 Mar 2007 03:02:30 GMT

Andy,

There is insufficient data upon which to form an opinion.

The symptoms described in the most recent posting could easily be the result of either network loading, CPU saturation, paging, or IO. I have seen situations where each of these can give rise to the symptoms described.

I have identified and resolved client situations caused by each of the above areas. In the network area alone, different clients have had the symptoms produced by:

- LAN saturation
- incorrect LAN hardware configuration
- incorrect (illegal) LAN topology
- malfunctioning hardware

Sometimes the underlying cause was a single one of these; sometimes it was a combination.

In each case the answer was the same: gather data and analyze it to understand what is the reason for the perceived slowdown.

It is much the same as walking into a doctor's office with a fever. It could be anything from the common cold to cancer. Tests and analysis is needed to uncover the underlying cause.

If I am unclear, please feel free to ask. If you wish to speak offline, I will be happy to do do.

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

Re: Session Slowdowns after noon times?

Jan van den Ende — Thu, 29 Mar 2007 04:51:40 GMT

Andy,

as several others have already remarked: much too many variables and too little data to pinpoint this issue (or maybe these issues?)

One potential hint:
>>>
Another example would be whenever I cancel an order after I press ENTER, it just takes a long time to clear everything from the screen.
<<<
Here my first guess would be an application issue. Is some batch active at this time that might do some extra lockongs?
OTOH, such batch might just cause system overload.
Does only this app have problems, or everything on this system?
Or is the system relatively idle, but the network overloaded?
The answer to such questions are only a beginning, to point to the way for deeper searches.

Really, your most exact and fastest (and therefor, in the end cheapest) solution will be to hire an experienced consultant, either on site or remote hands-on, to look into every aspect.
(I am not available now or in the forseeable future, but look through this and several other recent threads, and you will be able to pick one located "relatively near" about any place on earth).

hth

Proost.

Have one on me.

jpe

Re: Session Slowdowns after noon times?

Peter Zeiszler — Thu, 29 Mar 2007 09:05:56 GMT

Unless your system is running in a closet that has no air conditioning or air circulation an overheating condition is highly unlikely. If you do have it in a closet with temperatures going over 100 degrees - invest in a small computer room or air conditioner.

Today - go look at downloading and setting up T4. T4 is a data collection/performance analysis tool. It can generate tons of charts and data details to help troubleshoot.

Also, setup multiple windows. Do these before noon and after noon. The before is to get an idea of what you have running.
In one of the windows run "monitor /sys"
This will show you basically what kind of load you have going on. Watch the numbers for awhile to get an idea. Then as your system slows down see if you are running a heavy load.
If you think its CPU related in a window do "mon proc/topcpu".

Engage the networking group to watch your subnet to see if you have an overloaded LAN segment. Check if you have backups running.

The real solution is to get someone that is experienced with VMS and that can use the built in tools or can install additional tool (or recommend tools) for performance monitoring & analysis.

Monitor does have the capability of capturing the data to a file. That may be useful.
T4 does capture the data to files and can also create charts and excel formatted files.

Once you can start pin-pointing what you see and can capture useful data, then you can ask questions here concerning that data and get a myriad of opinions.

Re: Session Slowdowns after noon times?

Hein van den Heuvel — Thu, 29 Mar 2007 09:50:00 GMT

It pretty much has all been said already.
Be sure to carefully read and re-read all replies.
- get up to speed on basic performance monitoring on OpenVMS. "Monitor", T4,...
- consider working with a party which already has that experience

>> If were to select a command from the menu option screen, it says LOADING....and this usually takes about 5 to 10 seconds to load to the other screen.

That's not too impressive. Sad even.
It could suggest a poorly tuned system/appliaction 'on the edge'. Any minor disturbance might put it over the edge.
Maybe a BATCH job which launched aroudn noon?

It is often the DATABASE + IO subsystem which largely define the application performance. You may want to start investigating what that DB is (Flat files? Indexed files? Oracle?... ).

Again, the application may have been operating 'on the edge' and now trips over around noon, but soon will become slower all day.

This system is still using the VIOC file cache. You may find that upgrading to OpenVMS V7.3 (preferrably V7.3-2) will get you the XFC cache which may well melt all performance problems away... if they were caused by excessive disk read IO.

http://h71000.www7.hp.com/doc/73final/6017/6017pro_077.html

Good luck!
Hein van den Heuvel ( at gmail dot com )
HvdH Performance Consulting

Re: Session Slowdowns after noon times?

Hoff — Thu, 29 Mar 2007 10:05:44 GMT

It is possible for a processor that is overheating to go into a degraded or lower-powered state. It's just that Alpha systems don't have that particular feature. Alpha systems tend to log errors via various and box-dependent means, and -- if the overheating is not corrected -- then they shut down. Hard.

It's also possible that a marginal or failing disk is throwing errors and slowing operations, but this is both very unusual and not typically time-sensitive. And these suckers don't usually last very long after visible indications of self-cooking syndromes are manifested. Marginal memory can also throw correctable errors, and these can trigger similar slow-downs.

Errors, however, are generally logged and visible via SHOW ERROR and via the error log. And I concur with the rest of the herd: until proven otherwise, I too don't think that this case involves thermal or disk or memory.

As others have stated: load T4 or MONITOR, and track your system activity.

Network and host activity are among the most likely culprits, though the realm of possibilities is legion. It could simply be that fragmentation or memory or system usage has simply increased, and has now reached visibility after lunch.

Stephen Hoffman
HoffmanLabs