topic Re: XFC Cache in Operating System - OpenVMS

XFC Cache

Dan Herron — Wed, 26 Oct 2005 08:58:14 GMT

I am trying to turn off XFC caching for some files using the command:
"set file _$3$DKD103:[DB.FMS_MTHEND]*.*;*/CACHING_ATTRIBUTE=NO_CACHING".

A subsequent DIR/FUL of the files reveals that caching IS turned off:
dir/ful _$3$DKD103:[DB.FMS_MTHEND]FMS_MTHEND.RDB;1

Directory _$3$DKD103:[DB.FMS_MTHEND]

FMS_MTHEND.RDB;1 File ID: (388,39,0)
Size: 286/546 Owner: [MIS,WIRT]
Created: 1-OCT-2005 06:00:22.34
Revised: 26-OCT-2005 08:44:06.01 (116)
Expires:
Backup:
Effective:
Recording:
Accessed:
Attributes:
Modified:
Linkcount: 1
File organization: Sequential
Shelved state: Online
Caching attribute: No_caching
File attributes: Allocation: 546, Extend: 0, Global buffer count: 0, No version limit, Contiguous best try, Backups disabled
Record format: Undefined, maximum 0 bytes, longest 0 bytes
Record attributes: None
RMS attributes: None
Journaling enabled: None
File protection: System:RWED, Owner:RW, Group:, World:
Access Cntrl List: (IDENTIFIER=[SYSTEM],ACCESS=READ+WRITE+CONTROL+BIT_5+BIT_6+BIT_7+BIT_8+BIT_9+BIT_10+BIT_11+BIT_12+BIT_13+BIT_14+
BIT_15+BIT_16+BIT_17+BIT_18)
Client attributes: None

But the SHOW MEM command seems to indicate that the files are still being cached!?

sh mem/cache=file=_$3$DKD103:[DB.FMS_MTHEND]*.*
System Memory Resources on 26-OCT-2005 08:53:39.22

Extended File Cache File Statistics:

_$3$DKD103:[DB.FMS_MTHEND]FMS_MTHEND.RDB;1 (open)
Caching is enabled, active caching mode is No Caching
Allocated pages 0 Total QIOs 45
Read hits 0 Virtual reads 32
Virtual writes 13 Hit rate 0 %
Read aheads 0 Read throughs 0
Write throughs 0 Read arounds 32
Write arounds 13

These are Oracle Rdb database files and I have closed and opened the database after issuing the SET FILES command, but the SH MEM still shows cache activity on the files.
Can anyone explain this behaviour?
Am I not doing something correctly?

Thanks for your help,
Dan Herron

Re: XFC Cache

Peter Barkas — Wed, 26 Oct 2005 09:10:02 GMT

Which version of OpenVMS are you running and do you have patched and ECOs installed? I think there was a problem with earlier versions.

Re: XFC Cache

Peter Barkas — Wed, 26 Oct 2005 09:12:59 GMT

I've just found this, may be helpful:

http://forums1.itrc.hp.com/service/forums/bizsupport/questionanswer.do?threadId=298887

Re: XFC Cache

Robert_Boyd — Wed, 26 Oct 2005 09:14:51 GMT

Dan,

I'm not sure what you are seeing as the problem -- active caching mode is "No Caching" and allocated pages is 0. This means there are no system resources allocated to caching for the file in question.

The "Caching is enabled" I believe indicates only that caching is enabled at the system level.

Robert

Re: XFC Cache

Robert_Boyd — Wed, 26 Oct 2005 09:20:23 GMT

I think that short of a reboot -- you might see that when Oracle is shut down and re-opens the database that the file will then dissappear from the cache altogether.

You might get the same effect if you can do a shared open against it with Oracle up and running, but if Oracle has it open for exclusive access you won't be able to pull that off.

Robert

Re: XFC Cache

Dan Herron — Wed, 26 Oct 2005 09:54:53 GMT

Thanks for all your help!
It was the "CACHING IS ENABLED" that was throwing me for a loop.

Re: XFC Cache

Jan van den Ende — Wed, 26 Oct 2005 11:50:10 GMT

Dan,

from your Forum Profile:

I have assigned points to 5 of 22 responses to my questions.

Some of those are quite old.

Maybe you can find some time to do some assigning?

http://forums1.itrc.hp.com/service/forums/helptips.do?#33

Mind, I do NOT say you necessarily need to give lots of points. It is fully up to _YOU_ to decide how many. If you consider an answer is not deserving any points, you can also assign 0 ( = zero ) points, and then that answer will no longer be counted as unassigned.
Consider, that every poster took at least the trouble of posting for you!

To easily find your streams with unassigned points, click your own name somewhere.
This will bring up your profile.
Near the bottom of that page, under the caption â My Question(s)â you will find â questions or topics with unassigned points â Clicking that will give all, and only, your questions that still have unassigned postings.

Thanks on behalf of your Forum colleagues.

PS. â nothing personal in this. I try to post it to everyone with this kind of assignment ratio in this forum. If you have received a posting like this before â please do not take offence â none is intended!

Proost.

Have one on me.

jpe

Re: XFC Cache

Dan Herron — Wed, 26 Oct 2005 12:01:01 GMT

Jan,
Thanks for the reminder.
I have been derelict in my duties as a Forum user!!