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MainCachePagesInUsePercentage

4 posts in General Discussion Last posting was on 2013-01-24 12:55:49.0Z
GS Posted on 2012-12-12 08:23:23.0Z
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From: GS
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Subject: MainCachePagesInUsePercentage
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We always have maincachepagesinusepercentage on 100 % in our
IQ 15.4 on SPARK Solaris. TempCachePagesInUsePercentage
parameter changes (normally?) as seen from sp_iqstatistics.
MC amount is 9300, TC 13200 MB.
Can anybody explain the situation?


Abhijit Jadhav Posted on 2012-12-20 09:55:01.0Z
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From: Abhijit Jadhav
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Subject: Re: MainCachePagesInUsePercentage
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There should not be issue with sp_iqstatistics

Cross check with values reported in sp_iqstatus
select * from sp_iqstatus() where Name like '%IQ Buffers%';

Regards,
Abhijit

> We always have maincachepagesinusepercentage on 100 % in
> our IQ 15.4 on SPARK Solaris.
> TempCachePagesInUsePercentage parameter changes
> (normally?) as seen from sp_iqstatistics. MC amount is
> 9300, TC 13200 MB. Can anybody explain the situation?


queryplande Posted on 2013-01-11 00:05:26.0Z
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From: queryplande
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Subject: Re: MainCachePagesInUsePercentage
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> We always have maincachepagesinusepercentage on 100 % in
> our IQ 15.4 on SPARK Solaris.
> TempCachePagesInUsePercentage parameter changes
> (normally?) as seen from sp_iqstatistics. MC amount is
> 9300, TC 13200 MB. Can anybody explain the situation?

Perhaps your questions is about why the caches show this
behaviour?
Well, the main cache works best when it stores always data
that is on harddisk. When somebody tries to request data
from harddisk and it can be found in the cache the response
of the server is quicker. That's why the main cache does not
frees it's storage area when it is filled. It can be read
again.
The temp cache stores intermediate data which is only
relevant to one connection. After the connection ends the
transaction this data can not be reused (read agian)
therefore it may be dropped from the temp cache area.
Does this explanation helps or you need further info?


GS Posted on 2013-01-24 12:55:49.0Z
Sender: 171c.51012a4a.1804289383@sybase.com
From: GS
Newsgroups: sybase.public.iq
Subject: Re: MainCachePagesInUsePercentage
X-Mailer: WebNews to Mail Gateway v1.1t
Message-ID: <51012f55.18ad.1681692777@sybase.com>
References: <50ef5746.44fd.1681692777@sybase.com>
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Date: 24 Jan 2013 04:55:49 -0800
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Article PK: 1307153

These aspects are well known, thank you. But Sybase Control
Center seems not to understand this and shows "red" alert.

> > We always have maincachepagesinusepercentage on 100 % in
> > our IQ 15.4 on SPARK Solaris.
> > TempCachePagesInUsePercentage parameter changes
> > (normally?) as seen from sp_iqstatistics. MC amount is
> > 9300, TC 13200 MB. Can anybody explain the situation?
>
> Perhaps your questions is about why the caches show this
> behaviour?
> Well, the main cache works best when it stores always data
> that is on harddisk. When somebody tries to request data
> from harddisk and it can be found in the cache the
> response of the server is quicker. That's why the main
> cache does not frees it's storage area when it is filled.
> It can be read again.
> The temp cache stores intermediate data which is only
> relevant to one connection. After the connection ends the
> transaction this data can not be reused (read agian)
> therefore it may be dropped from the temp cache area.
> Does this explanation helps or you need further info?