system tuning and bottle necks

[vmsserbo]

I am using Vaxes . Give me examples of commands using Dynamic Load Balancer Plus

MIles

[Arch_Muthiah]

Miles,

You can download DLB Plus here....
http://www.ttinet.com/dlbplus.html

And you can find the docs here...
http://www.ttinet.com/doc/dlbplus_clean.html

hope this solve your problem.


Archunan

[Arch_Muthiah]

Miles,

Once you install DLB Plus, Just start DLBPLUS using DLBPLUS_STARTUP.COM
and it is a menu based and start main menu using DLBPLUS.COM, there you can find so many options you can choose....



Archunan

[Guillou_2]

Hi,

you can find information about performance and bottleneck at this link:
http://h18000.www1.hp.com/support/asktima/operating_systems/009BD243-C877FC20-1C0186.html

regards

Steph.

[comarow]

Do you have a support contract? We have a document called the performance cookbook which is a step by step method for looking at a system.

The first step has to be Monitor.

Monitor system will look at CPU utilization,
CPU queue, memory and overall activity.
The CPU queue is especially useful as if you have it stacking up on an AVERAGE of 1 of more, you have a CPU bottleneck.

$monitor DISK/item = queue
OTHER than when backups are running
(backup purposely queue up I/Os)
If you see on the AVERAGE queue depths of 1 or greater, the disk is saturated. Often you can simply move hot files off the disks with a problem.

$monitor page
will look at your page faults. However, that takes some understanding to look at.
The Performance Cookbook provides much information.

You can create monitor reports. In
Sys$examples there are several automated monitor programs which will monitor your system and send you the reports. I personally prefer 15 minute snapshots when your system is busy.

$show system
itself is a very useful command. It will show the process states. Are there any unusual states? A lot of Com stated.

$mon lock
will show the number of locks, and their states. Are there a lot waiting?

$show mem/file
will show how much space is left in your pagefile. If your pagefile gets low in free space, it will crawl, and at around 0 free your system will hand.

$show mem/full/pool
compare the initial size of npagedyn to the current size. If it has significantly expanded time to run autogen with feedback.
You might wish to put the current size as the min size
min_npagedyn=current
when you run autogen with feedback
$autogen savparams setparams
Your system must have been up for at least 24 hours and make sure it had the full load.
Look at the report and make sure there were no fatal errors.


Similarly, when you do $show mem/full/pool you want PAGEDYN to be at least 50% free.

Someone suggested dynamic load balancer. Sometimes that may work, but I've seen systems where IT was the problem. We turned it off and improved performance. I tend to think it was better in earlier versions of VMS.

VIOC is a cache to improve I/O. In more recent versions of VMS.
$show mem/cache/full
will show the size and how well it is working.
We have an article on reading it and using it.

VCC_MAXSIZE is the sysgen parameter that will increase it's size.
add
MIN_VCCMAXSIZE to modparams.dat

Of course, the ultimate test is to log on to the system, try a number of command, including the applications. You certainly can have application slowdowns.

Finally, I would like to point out that
Colorado Support does offer VAST or custom consulting, and can analyze your performanc situation, identify bottlenecks and offer solutions.

[Robert Gezelter]

Miles,

While listening to your users is always a good idea, it can be quite misleading.

I have encountered many sites where truly miserable performance is accepted as normal, because it has been that way for a LONG LONG time.

While all of the sophisticated tools are nice, you can glean a huge amount of information from simply running MONITOR and looking at several parameters.

Good tuning is a question of identifying what is limiting performance, and fixing that issue. Then iterate again, fixing the next problem. When you have a system where there are no factors that are limiting performance (other than shortage of work), you are done, at least for the moment.

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

[Allan Bowman]

The simplest solution is to use MONITOR and AUTOGEN on a regular basis.

You can set up MONITOR as a continuously running process with daily reports, or you may just need to run it manually for a few minutes once a week - it totally depends on how volatile your environment is. If you are not adding new applications or lots of users, you may just need to check things out once a month or so. If there are frequent changes, you should run it often, or use one of the other tools that others have mentioned.

You can periodically run AUTOGEN with FEEDBACK just up to the reporting phase. Look at the reports generated and see if any of the recommended changes appear to be significant enough to implement.

If your 80 systems are identical, you should only need to look at one of them on a regular basis and apply any changes to all of them.

Allan in Atlanta

[Jan van den Ende]

Miles,

although I do agree with Allan that 80 more-or-less identical systems should reduce your effort considerably, in my view that is for a totally different reason.

Collect your metrics (any of the aforementioned tools), but generally you have only to look at the summaries, and COMPARE THOSE.

Any system sticking out is the one that deserves special attention.

If a system appears to do much worse than the others, you need to find the cause. If it is just a lot of extra load, maybe that can be re-distributed? Anyway, the heaviest loaded system will be the one that gives the strongest response to any changes, so that is the one you will need to work on.

If a system does much BETTER than the others (without just having little to do) investigate THAT one also! It might just tell you how to improve all others!

hth

Proost.

Have one on me.

jpe