topic Re: Are there any Problems for Memory ? in Operating System - OpenVMS

Are there any Problems for Memory ?

iman_1 — Fri, 15 Dec 2006 09:52:50 GMT

Dear All,

My Show memory shows the below output

System Memory Resources on 15-DEC-2006 14:57:47.54

Physical Memory Usage (pages): Total Free In Use Modified
Main Memory (768.00Mb) 98304 8477 67388 22439

Virtual I/O Cache (Kbytes): Total Free In Use
Cache Memory 20480 0 20480

Granularity Hint Regions (pages): Total Free In Use Released
Execlet code region 1024 0 501 523
Execlet data region 128 5 123 0
VMS exec data region 12462 0 12462 0
Resident image code region 1024 0 811 213

Slot Usage (slots): Total Free Resident Swapped
Process Entry Slots 167 83 84 0
Balance Set Slots 165 83 82 0

Dynamic Memory Usage (bytes): Total Free In Use Largest
Nonpaged Dynamic Memory 98893824 89637888 9255936 86346112
Paged Dynamic Memory 2564096 853904 1710192 844912

Paging File Usage (blocks): Free Reservable Total
DISK$LDAS01_SYS:[SYS0.SYSEXE]SWAPFILE.SYS
88960 88960 88960
DISK$LDAS01_SYS:[SYS0.SYSEXE]PAGEFILE.SYS
1004016 452736 1149568
DISK$OMSDB_DSK2:[PAGEFILE]SECPAGEFILE.SYS;1
871024 392896 999936

Of the physical pages in use, 17868 pages are permanently allocated to OpenVMS.

Is there any memory shortange on the above system ?

Regards

Re: Are there any Problems for Memory ?

Volker Halle — Fri, 15 Dec 2006 10:01:28 GMT

Iman,

why do you ask ? Are you seeing any problems ? Your SHOW MEMORY data looks o.k. to me. Nonpaged pool looks a bit over-sized, but you didn't tell us the state the system was in.

Volker.

Re: Are there any Problems for Memory ?

iman_1 — Fri, 15 Dec 2006 10:14:37 GMT

Volker,

Yes, Im having memory dumps as below

Current PROCESS DEC Rdb environment is version V5.1-1 (MULTIVERSION)
Current PROCESS SQL environment is version V5.1-1 (MULTIVERSION)
Current PROCESS Rdb/Dispatch environment is version V5.1-2 (MULTIVERSION)
%SYSTEM-F-ACCVIO, access violation, reason mask=00, virtual address=00000000, PC=0003C48C, PS=0000001B
%TRACE-F-TRACEBACK, symbolic stack dump follows
Image Name Module Name Routine Name Line Number rel PC abs PC
TASK DEMAND df_demand 3442 000007EC 0003C48C
TASK PN process_node 7010 000011DC 00034A5C
TASK PSMBX process_stdmbx 4223 00000158 00030328
TASK TASK task 2375 0000008C 0003008C
0 A273E170

We have increased the pgflquo for the users running this process from 250000 to 500000. Still the process are failing again.

Re: Are there any Problems for Memory ?

Robert Gezelter — Fri, 15 Dec 2006 10:23:31 GMT

Iman,

If you are getting ACCVIO, I would be surprised if the problem is limits on memory. RDB should handle resource shortages more gracefully than that.

Have you logged a support case with RDB??

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

Re: Are there any Problems for Memory ?

Volker Halle — Fri, 15 Dec 2006 11:13:49 GMT

Iman,

%SYSTEM-F-ACCVIO, access violation, reason mask=00, virtual address=00000000, PC=0003C48C, PS=0000001B

the instruction at PC=3C48C is trying to access virtual address 0, which is a non-access page. This is a bug in whatever image/software you are running here (most likely RDB). Try to obtain and install the most current version/patch level.

Volker.

Re: Are there any Problems for Memory ?

Volker Halle — Fri, 15 Dec 2006 12:25:19 GMT

Iman,

we might have been misguided by the RDB process environment initialisation messages. The problem seems to happen in an image named TASK.EXE:

Image Name Module Name Routine Name Line Number rel PC abs PC
TASK DEMAND df_demand 3442 000007EC 0003C48C
...

This is either a self-written application or a third-party application running on your system. Find out who's supporting that application/image and address the issue with them.

Volker.

Re: Are there any Problems for Memory ?

Ziggy Filek — Fri, 15 Dec 2006 16:58:27 GMT

"Is there any memory shortange on the above system ?"

I'd say YES. 768 Mb is very puny to run a memory intensive application like Oracle Rdb. You actually have high paging file's usage: with today's lower memory prices this should not be allowed to happen. I run Oracle (9.1, not Rdb) on my cluster and have a SGA (Sysem Global Area - memory mapped)of 10GB out of total memory of 32GB.

Ziggy

Re: Are there any Problems for Memory ?

Robert Gezelter — Fri, 15 Dec 2006 17:32:09 GMT

Ziggy,

WADU, I disagree. Without detailed statistics about IO and paging rates, and a look at the database and applications, any conclusions as to "increase" the memory are, IMO, premature.

While it is true that at today's prices, it seems like memory is the cheapest solution, it is often just a band aid.

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

Re: Are there any Problems for Memory ?

Volker Halle — Sat, 16 Dec 2006 02:15:44 GMT

Ziggy,

I also have to disagree regarding your observation:

You actually have high paging file's usage:

Both pagefiles are 87% free, i.e. only 13% used. The goal is to keep the pagefile usage below 50%.

Whether there is enough memory provided for the application, depends on the actual demand of the application. Measing paging rates would be the best indicator of memory shortage at runtime.

When speculating about a possible 'virtual memory' shortage (i.e. PGFLQUOTA), you also need to look at the process memory usage, not the overall system memory usage.

Volker.