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Problems with the MOUNT system service

 
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Christopher Blackburn
Frequent Advisor

Problems with the MOUNT system service

I have some software than mounts a magnetic tape using the system service $MOUNT. After moving to VMS 8.2 the system service now returns the error %MOUNT-F-LKWSETFUL and fails to mount the tape. The VMS command MOUNT works as expected. I have looked at the process quotas for its working set and these are much the same as on the previous version of VMS.
Anyone any ideas ?
13 REPLIES
Heinz W Genhart
Honored Contributor

Re: Problems with the MOUNT system service

Hi Christopher

$ help /message LKWSETFUL

gives the following information


LKWSETFUL, locked portion of working set is full

Facility: SYSTEM, System Services

Explanation: No more pages can be locked in the working set because there
would not be enough remaining pages available dynamically for
the image to continue execution.

User Action: Use the DCL command SET WORKING_SET to increase the working
set limit, if the limit is not already set at the maximum
allowed. If the working set limit is already at the maximum
allowed, correct the program that attempted to lock too many
pages in the working set.


Hope that helps

regards

Heinz
Ian Miller.
Honored Contributor

Re: Problems with the MOUNT system service

You may find that more pages are being locked in the working set than previously and therefore have to increase the quotas.

You should review the quotas of all usernames. There is some dcl to help with this at
http://dcl.openvms.org/stories.php?story=05/07/28/2894075
____________________
Purely Personal Opinion
Robert Brooks_1
Honored Contributor

Re: Problems with the MOUNT system service

Do you have the sources for this software? If not, who is the vendor? Locking pages in a working set changed for V8.2 (both Alpha and I64) such that an attempt to lock a page from an image will lock the entire image.

This has caused some problems (especially with BEA MessageQ), so we're going to restore the old behaviour on Alpha for users of the $LCKWSET system service.

-- Rob
Christopher Blackburn
Frequent Advisor

Re: Problems with the MOUNT system service

Many thanks for all your replies.

In answer to some of the questions, the source code was written and is owned by ourselves. I don't believe any pages are explicitly locked into memory but I will check. The process quotas have not changed from VMS 7.3 to 8.2 but again I will check the user/process quotas for the working set and adjust.
During my initial investgations I did try to increase the working set QUOTA but it did not appear to make any difference, as soon as the SYS$MOUNT service is called the LKWSETFUL error is returned.
Wim Van den Wyngaert
Honored Contributor
Solution

Re: Problems with the MOUNT system service

Which quota did you modify ?

You need to modify wsquo. wsextent is only given after pagefaulting a lot. The only thing that's sure is that you got wsquo.

Wim
Wim
Christopher Blackburn
Frequent Advisor

Re: Problems with the MOUNT system service

Many thnaks again for your answers.

I've just found by updating the WSQUOTA from 8192 to 65535 the MOUNT system service completes without error. I have adjusted the user account entry for the user that runs the process. I have checked the actual quota assigned to the process by using the GETJPI lexical function and it is now correctly set to 65535.
When I look at the process using SHOW PROC/CONT the working set is shown as 3728.
This seems to have sorted the problem out - Many thanks to all.
Wim Van den Wyngaert
Honored Contributor

Re: Problems with the MOUNT system service

What went wrong in your previous increase ? Wrong parameter or not enough increase ?

Wim
Wim
Christopher Blackburn
Frequent Advisor

Re: Problems with the MOUNT system service

Problem with last attempt was incresing the
process parameter but not having sufficient quota for the user account from which the process is started.
All seems OK now, but all processes started from the modified user account will get the newly increased working set quota ! I'm not sure what the effect of this will be on the overall system page usage.
Volker Halle
Honored Contributor

Re: Problems with the MOUNT system service

Christopher,

as a workaround, you could add a SET WORKING_SET/QUOTA=8192 command into that user's LOGIN.COM to limit the working set quota for that user's account.

Just before starting the image, that uses the $MOUNT system service, increase the process WSQUOTA up to authorized limit with $ SET WORKING_SET/QUOTA=65535 and reset it back to 8192 after the image has finished.

Volker.
Christopher Blackburn
Frequent Advisor

Re: Problems with the MOUNT system service

Thanks Volker Halle, I will give that a try.
Ian Miller.
Honored Contributor

Re: Problems with the MOUNT system service

The quota, pages reserved in page files and pages used in page files are all different things. Increasing a quota does not mean processes will definately use more pages in page files
____________________
Purely Personal Opinion
Christopher Blackburn
Frequent Advisor

Re: Problems with the MOUNT system service

Many thanks for all the replies/suggestions. Increasing the process working set quota has resolved the problem and the SYS$MOUNT service can now be called successfully.
Volker Halle
Honored Contributor

Re: Problems with the MOUNT system service

Christopher,

the V8.2 LKWSET change has been restored to the V7.3-2 behaviour in patch VMS82A_SYS-V0500 released today.

Volker.

5.2.1 Performance Degradation

5.2.1.1 Problem Description:

In V8.2, a behavioral change was made to OpenVMS when
locking pages into the working set. If the virtual
address range requested fell within an image, then the
entire image was locked into the working set. For
applications that frequently perform this operation, this
behavioral change can result in a severe performance
degradation.

The behavior of the system services to lock and unlock
the working set is being restored to the prior V7.3-2
behavior of locking only the pages requested.

Applications that need to lock and unlock the entire
image into the working set should use the
LIB$LOCK_IMAGEand LIB$UNLOCK_IMAGE routines which were
provided with OpenVMS V8.2.