NetView/6000 V2R1 : ovwdb '-n' option
ITEM: RS4000016654
**************> QUESTION level 1 --> level 2 SPECIALIST <**************
Our customoer managing larg Network using NetView/6000 V2R1. Their NW
has about 20000 IP nodes and the number of objects in object_DB of
NV/6K reaches to 40000.
In our test environment, the number of objects in object_DB had reached
to about 20000 and the performance of NV6K has been wrong. We tried to
increase the size of 'ovwdb's object cache' by changing '-n' option,
from -n5000(default) to -n25000 and performance of NV6K has been
improved.
We have a plan to increase object cache size of ovwdb from 5000
to 40000.
Is there any limitation of object cache size of 'ovwdb'?
(Could we set number freely to -n option ?)
Thanks a million ¢¢
************** ANSWER level 2 -- level 1 SPECIALIST **************
==== THIS TEXT HAS BEEN ENTERED BY IBM IN USA
==== RESP: NHL AT WTSCPOK ======================== DATE:960117
TIME:0708
We have received your question and assigned it to a specialist. We
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==== THIS TEXT HAS BEEN ENTERED BY IBM IN USA
==== ASGN: NHL AT WTSCPOK ======================== DATE:960117
TIME:0715
The question has been re-assigned to SHOGREN.
************** ANSWER level 2 -- level 1 SPECIALIST **************
==== THIS TEXT HAS BEEN ENTERED BY IBM IN USA
==== RESP: SHOGREN AT WTSCPOK ======================== DATE:960117
TIME:1157
I will check -- but, in the meantime let me know what numbers you test
with and how the performance improves. I don't mean that you need to
do exact performance "measurements" or anything, just a feeling for
what you mean by: Performance improves (you must have some way you
"measure" that it improves or you just get a good feeling it does?)
Thanks.
**************> QUESTION level 1 --> level 2 SPECIALIST <**************
====> THIS TEXT HAS BEEN ENTERED BY IBM IN JAPAN
Sorry for my insufficient exposition.
I have no exact performance measurements about ovwdb cache size.
The "improvement" is by just feeling.
Regards.
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====> RESP: NHL AT WTSCPOK ======================== DATE:960118
TIME:0725
We have received your question and assigned it to a specialist. We
will respond as soon as possible.
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TIME:0753
The question has been re-assigned to SHOGREN.
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====> RESP: SHOGREN AT WTSCPOK ======================== DATE:960118
TIME:0938
OK, I will let you know when the developers get back to me.
I looked in the online documentation (I assume you did as well) and
the discussion is "only" a memory discussion -- so, it is possible
the practical limit is memory. But, let's wait and see what they say.
Thanks.
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====> THIS TEXT HAS BEEN ENTERED BY IBM IN USA
====> RESP: SHOGREN AT WTSCPOK ======================== DATE:960118
TIME:1608
As far as I can find out, the only practical upper limit is memory.
**************> QUESTION level 1 --> level 2 SPECIALIST <**************
====> THIS TEXT HAS BEEN ENTERED BY IBM IN JAPAN
Thanks for yor note.
But I have one more question about ovwdb cache size.
Development suggested that setting the cache size to 0.
What does it mean ? Ovwdb uses no cache ? Or ovwdb dynamically
allocates a block of memory in propotion to the number of objects ?
Thanks in advance.
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====> THIS TEXT HAS BEEN ENTERED BY IBM IN USA
====> RESP: NHL AT WTSCPOK ======================== DATE:960122
TIME:0726
We have received your question and assigned it to a specialist. We
will respond as soon as possible.
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====> ASGN: NHL AT WTSCPOK ======================== DATE:960122
TIME:0829
The question has been re-assigned to SHOGREN.
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====> THIS TEXT HAS BEEN ENTERED BY IBM IN USA
====> RESP: SHOGREN AT WTSCPOK ======================== DATE:960126
TIME:1201
From development:
The cache size of 0 means all ovwdb objects will be kept
in memory. cache size of x (greater than 0) means only
x objects will be kept in memory.
The following points are from NetView for AIX V3 testing and are added
here for information.
1) Performance might improve for the customer by setting the cache
size to 0. I would ask the customer to make a database backup
for safety, and then, set the cache size to zero and see how
things go.
2) Also, we believe if you set the cache size too high (40,000?),
ovwdb might try to allocate a block of memory larger than that
allowed
by the operating system. We will make a change in the next
PTF that should avoid this problem. All the more reason to try
a "0" cache size.
3) However: Be careful. The work I am doing is in Version 3. There
have been changes from Version 2 to Version3 that could muddy
the water when making the recommendations of using a 0 cache size.
ovwdb will work better (faster) if you use a larger cache size.
My understanding is, your cache size should be a little more
than the number of objects in your database.
WWQA: ITEM: RS4000016654 ITEM: RS4000016654
Dated: 01/1996 Category: AIX6000
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