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Re: Free list size on mon system (alpha)

 
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Kendall McCarthy_2
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Free list size on mon system (alpha)

I have a question regarding the mon system screen . I notice that the free list was down to around 14,000 on the free list graph. I was assured that this is not an issue. Is this the case? (running VMS 7.3-2 on alpha)
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Jim_McKinney
Honored Contributor

Re: Free list size on mon system (alpha)

Probably not - you bought the memory so you might as well use it, right?

Is XFC active - see your SHOW MEMORY output - and if so how much memory is it holding? It's adaptive and takes what isn't used up to a configurable threshold - if need be, it'll automatically return memory to the free list so that user processes can be satisfied.

Any outswapped processes?
Ian Miller.
Honored Contributor

Re: Free list size on mon system (alpha)

14,000 compared to how many pages of memory. For a quick look at memory use then MONITOR CLUSTER gives a percent.

However, what is the real problem?
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Kendall McCarthy_2
New Member

Re: Free list size on mon system (alpha)

Vol is in full XFC mode .

How do I tell how much it is holding?
Jim_McKinney
Honored Contributor

Re: Free list size on mon system (alpha)

Example:

$ sh mem/full
System Memory Resources on 1-APR-2008 13:25:41.91

Physical Memory Usage (pages): Total Free In Use Modified
Main Memory (768.00MB) 98304 5893 81292 11119

Extended File Cache (Time of last reset: 9-DEC-2007 12:09:40.43)
Allocated (MBytes) 366.89 Maximum size (MBytes) 384.00


This system has 768 MB and the XFC is using nearly half of it (366 MB).
Kendall McCarthy_2
New Member

Re: Free list size on mon system (alpha)

monitor cluster gives me 99% memory used on this node. There are no issues . I just saw the low free list and saw it as a potential issue.
Kendall McCarthy_2
New Member

Re: Free list size on mon system (alpha)

$ sho mem/full System Memory Resources on APRIL 1, 2008 04:31 PMPhysical Memory Usage (pages): Total Free In Use Modified Main Memory (4.00GB) 524288 38297 372854 113137Extended File Cache (Time of last reset: 16-MAR-2008 00:52:09.78) Allocated (MBytes) 987.21 Maximum size (MBytes) 2048.00


Although at this point free list is at 40,000
Hein van den Heuvel
Honored Contributor
Solution

Re: Free list size on mon system (alpha)

>> I notice that the free list was down to around 14,000 on the free list graph
>> I was assured that this is not an issue. Is this the case?

Sounds low, but it is probably just fine.
It could indicate that it is time to review load, growth, scaling.
14,000 down from 15,000? Out of 100,000 or out out 2,000,000 (16GB)

Memory on the free list is just wasted while sitting there. It is nice to have it as a reserve but it is better put to use in the XFC cache... knowning that will give back when neeeded.

So the "In use" or "Allocated" memory the XFC is a better indication for the memory pressure, assuming it is not artificailly limited by "maximum Size." As a bonus it is reported in Mbytes (or Gbytes as appropriate) so we don't have to think whether those 14,000

>> How do I tell how much it is holding?

$SHOW MEMORY /FULL

Hope this helps some,
Hein van den Heuvel (at gmail dot com)
HvdH Performance Consulting
Hein van den Heuvel
Honored Contributor

Re: Free list size on mon system (alpha)

Ah, time-collision on those replies.
I see some details now.

I would worry a little, but not a lot. I would try to plot XFC and Free memory over the past weeks and and interpret that in the larger picture of system usage and application updates. Did it step down when a new database was added, or did it creep down over time.
More users, or new functionality?
(Many) more users expected or a new plateau reached?
Those are the real questions, not the raw number out of context.

Cheers,
Hein.

Jim_McKinney
Honored Contributor

Re: Free list size on mon system (alpha)

Here's yours reformatted ( check that "retain format(spacing)" box below your reply when you compose ):

$ sho mem/full
System Memory Resources on APRIL 1, 2008 04:31 PM
Physical Memory Usage (pages): Total Free In Use Modified
Main Memory (4.00GB) 524288 38297 372854 113137

Extended File Cache (Time of last reset: 9-DEC-2007 12:09:40.43)
Allocated (MBytes) 987.21 Maximum size (MBytes) 2048.00


It shows that you've got 987 MB currently in use. So, nearly 1/4 of your memory is being used by the Cache. So, you've got no issues vis-a-vis the free list. You might examine more of that SHOW MEMORY output to see the efficiency of your XFC cache.