Sysgen parameters

[Sk Noorul Hassan]

H/W is VAX 4105/4106 A with 128 memory max. O/S is Open VMS 7.1 and an SCADA Application is running on it.

Questions : 1. Can WSMAX be increased beyond 16K
2. Can Pagefile2(size 166278) be increased as 'reservable' column in $ sho mem command is showing '-5644' pages
3. Can Napagedyn & Napagevir be decreased (current setting is 18579968 & 92901888 respectively)

Will increase or decrease of all these parameters value have direct impact on memory resources of the servers.

Pls suggest

[Karl Rohwedder]

Pagefile: The pagefile can be increased in size, if the disk on which it is located has enough space for it and the space is not too fragmented.

$ MC SYSGEN create pagefile2.sys/size=...

Pls. check your AUTOGEN report at the end for a recommendation conc. the page/swapfile sizes.

Npagedyn: For those parameter you should also check the AUTOGEN report. If there is plenty of free pool, may be that some MIN_NPAGEDYN settings in MODPARAMS.DAT prevent AUTOGEN from lowering those values.

Lowering NPAGEDYN frees memory, while increasing WSMAX occupies memory. The size of the pagefile has no direct impact on your free memory.

mfg Kalle

[Antoniov.]

You can do all increasing or decreasing but it's not clear how they impact on your system.
Before any change I prefer run autogen without reboot, then look at report generated. You can type @SYS$UPDATE:AUTOGEN HELP for furthermore information.

For my experience you can increase pagefile without trouble if disk is not too fragmented.

Antonio Vigliotti

[Mobeen_1]

Noorul,
As suggested by Antonio, i would prefer that you make use of AUTOGEN before doing anything. That will give you an overall picture of your system performance.

Do try to run AUTOGEN with FEEDBACK and review the report and then make a decision on the changes you intend to carry out

rgds
Mobeen

[Jan van den Ende · Accepted solution]

WSMAX of 16K is very small for a 128M system!
To find out if you can profit from a higher value, look at $ SHOW MEM/FIL.
The 'reservable' column is usually not very important, but 'used' is! Calculate 'used' from 'total' minus 'free'.

_IF_ you have pagefile use, then
How is your free memory?

Because, if you have small WSMAX, and small modified page list, then you force your processes to use the pagefile, while the system does not yet really need it.

A quite good way to optimise this, is to have it done dynamically by VMS.

Make your WSMAX at least as big as your biggest process at-its-biggest. (SHOW PROCESS/ID=.../CONT will help find that).
Same the WSEXTENT for the account that runs that process .
Let WSQUOTA for every account be more or less the value of the working set if the programm just loaded, before any real work is done.

Now, each process 'at rest' can fit in memory.
Each process 'at work' tries to stay in memory, and, as long as there is enough memory for those together, they succeed.
And, if memory _IS_ becoming scarse, now VMS is constantly refereeing who is best helped with available memory.

It will be very difficult to improve on the dynamic resource allocation that VMS can do itself,
PROVIDED THAT YOU LET IT!!

So, grant every process what it resonably needs under heavy load.

If it ever looks like you need a bigger pagefile, that _REALLY_ is the time to buy extra memory!! (or allow VMS to use what is already there).

hth,

Proost.

Have one on me.

Jan

[Ian Miller.]

Due to the relationships between various system parameters e.g WSMAX affects the size of each balance set slot and BALSETCNT sets how many - you should use AUTOGEN. If you are increasing WSMAX consider if BALSETCNT and MAXPROCESS count can be reduced.

[Jan van den Ende]

Ian,

by all means yes: whatever you plan to change, let AUTOGEN run through GENPARAMS and check the report!

If any incompatabilities would have been introduced, AUTOGEN will find out and tell ahead of a potential disaster.

I was intent on showing the direction for move, but it should never go further than AUTOGEN would allow.
A lot of those relations depend on architecture, version, memory size etc., so intentions can be given, but exact numbers always depend on specific hardware and application.

Proost.

Have one on me.

Jan

[Sk Noorul Hassan]

Hi jan,

thanks for your response.As per your suggestion, find the details
1. Pagefile.sys used is 2 lac blocks for a total of 3 lac blocks
2. Pagefile2.sys used is more than 2 lac blocks for a total of 3 lac blocks
3. WSMAX is 16K , WSEXTENT of the account is 8K.

Now as per your suggestion,
1. How to find biggest process and which parameter to look in from ( sh proc/id=../conti) ?

2. How to set WSQUOTA value of an account same as working set ?
3. How to make process memory resident ?


Please suggest.

[Jan van den Ende]

Sk,

It lloks like WSMAX is the real issue here.

I would guess that in your SYS$SYSTEM:MODPARAMS.DAT (or potentially in one of the files called from there by AGEN$INLUDE_FILE you have a line that reads
WSMAX = 16483 ( or maybe 16384 )

I suggest you change that:
MIN_WSMAX = 65535
and then run autogen
$ @SYS$UPDATE:AUTOGEN SAVPARAMS GENPARAMS

After that, in SYS$SYTEM you will find the AGEN report file.

Look at what AUTOGEN suggests for WSMAX now.

Better, copy the report file to a file with extension ".TXT", (because of firewall restrictions) and add that as an attachment.

We will take it from there.

Success.

Prosst.

Have one on me.

Jan

[Sk Noorul Hassan]

Hi jan,

Thanks. wsmax value=16248 is set in params.dat file.

Do u think if I increase the WSMAX value to 64K , I need to decrease the value for NPAGEDYN & NPAGEVIR to free memory space.

One thing, after increasing WSMAX value, do I need to do other changes like WSEXTENT, working space as suggested by you before.

please suggest

[Andy Bustamante]

NPAGEDYN will dynamically grow, but this can impact performance. Autogen will provide the peak use and you can tune around that. $ show memory/pool/full will tell you the inital (sysgen size) and current size.

How much free memory do you have on this sytem during your peak use period?

Working set size can also be checked with sys$examples:working_set.com. This provides some detail and a starting point for checking other quotas.

The negative value for pagefile2 is only a problem if "everything" tried to page out all at once. Depending on how much free memory you have and what else the system is doing, this may not be a problem. You can also install another pagefile. You should try to have contiguous page files.

[Uwe Zessin]

I would remove any WSMAX, PQL_MWSEXTENT setting from MODPARAMS.DAT. Starting with OpenVMS VAX V6.0, it will automatically set to the maximum possible value.

[Jan van den Ende]

Sk,

Do _NOT_ modify PARAMS.DAT !!
That file is maintained by the system and by AUTOGEN, and _NOT_ by the system manager.

Make the changes in MODPARAMS.DAT

-- Since your VMS version is below V7.2 , there still is a combined limit on WSMAX and MAXPROCESSCNT.
Do you have a very high MAXPROCESSCNT? and if so, do you really need it?

I really would like to see a recent AGEN$PARAMS.REPORT from your system.
If you specify GENPARAMS as the second param, _NOTHING_ will change on your system, but there is a full report on what _WOULD_ be changed by AUTOGEN.
Then we can go over the report, and decide which changes are likely to be for the good!

Please, DO post the report!

Proost.

Have one on me.

Jan