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RE: SGA info.

From: Viraj Luthra <viraj999_at_lycos.com>
Date: Sun, 12 Aug 2001 20:55:11 -0700
Message-ID: <F001.00368914.20010812205029@fatcity.com>

 Thanks Jon, Girijan,Seema,Hermanto for explanations; Sounds good to me, let me explore more of Oracle now....jee this is vast ocean called oracle but the journey is interesting, let me tell u that. oh i better get to work!

Thanks guys.

rgds,

raja

--

On Sun, 12 Aug 2001 19:35:48  
 Jon Walthour wrote:

>Raja:
>
>Let me see if I can explain it.
>
>As Girijan previously explained, some of this extra memory is taken up
>with the redo log guard pages. Guard pages are one memory protection
>unit in size and are there to prevent Oracle software bugs or hackers
>from corrupting the log buffer.
>
>Another portion of the memory results from a minimum size for the log
>buffer of 4 * db_block_size. This rounding up is reflected in v$sga, but
>not in v$sgastat. There is also a lot of "rounding up" and extra memory
>allocation like this going on with other structures in the sga to fill
>out full memory pages. This, too, is represented in v$sga, but not in
>v$sgastat.
>
>The remainder of the space is accounted for in the "empty pages" like
>the redo log buffer's guard pages that enclose various sga structures to
>avoid areas stepping on each other. These "empty pages" are also not
>accounted for in v$sgastat.
>
>HTH,
>
>Jon Walthour
>
>-----Original Message-----
>Luthra
>Sent: Sunday, August 12, 2001 10:41 PM
>To: Multiple recipients of list ORACLE-L
>
>
> Hello,
>
>Doing select * from v$sga shows:-
>
>NAME VALUE
>-------------------- ----------
>Fixed Size 67688
>Variable Size 18042880
>Database Buffers 16777216
>Redo Buffers 172032
>
>
>What do you mean by "presence of 2 guard pages for the log buffer"?
>
>Please explain.
>
>rgds,
>
>raja
>--
>
>On Sun, 12 Aug 2001 17:50:21
> Girijan Puthran wrote:
>>
>>Raja,
>> 16k of this difference might be with respect to the log buffer
>>size (most probably) and this is due to the presence of 2 guard pages
>>for the log buffer on some Operating systems, and as for the remaining
>>space--I am not too sure.
>>
>>
>
>> Girijan
>>
>>
>>---------------------------------------- Message History
>>----------------------------------------
>>
>>
>>
>>Please respond to ORACLE-L_at_fatcity.com
>>
>>To: ORACLE-L_at_fatcity.com
>>cc:
>>
>>
>>
>> Hello,
>>
>>I am running oracle 8.1.5.0.0 on hp11.
>>
>>If I select from V$sga I get at least 18104 more than what I see in
>>v$sgastat. Therefore I wanted to know why the figures are different and
>
>>what statistic in v$sgastat is not counted, and therefore the figure in
>
>>v$sgastat is low??
>>
>>I am getting some thing like this:-
>>
>>select sum(value) from v$sga;
>>
>>35059816
>>
>>select sum(bytes) from v$sgastat;
>>
>> 35041712
>>
>>Please comment if you can, thanks in advance.
>>
>>rgds,
>>
>>raja
>>--
>>
>>On Thu, 09 Aug 2001 10:25:21
>> Seema Singh wrote:
>>>Hermanto
>>>which version of oracle u r running?Just see following output
>>>SVRMGR> connect internal;
>>>Connected.
>>>SVRMGR> select sum(value) from v$sga;
>>>SUM(VALUE)
>>>----------
>>>1033101472
>>>1 row selected.
>>>SVRMGR> select sum(bytes) from v$sgastat;
>>>SUM(BYTES)
>>>----------
>>>1033044248
>>>1 row selected.
>>>SVRMGR> show sga
>>>Total System Global Area 1033101472 bytes
>>>Fixed Size 73888 bytes
>>>Variable Size 537395200 bytes
>>>Database Buffers 491520000 bytes
>>>Redo Buffers 4112384 bytes
>>>If u see all three output you can see the diffrence.The correct view
>>>to check size of sga is v$sga. Hope this will help u.
>>>Thanks
>>>-Seema
>>>
>>>
>>>
>>>>From: Hermanto P <hermanto_p_at_aprilasia.com>
>>>>Reply-To: ORACLE-L_at_fatcity.com
>>>>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>>>>Subject: RE: SGA info.
>>>>Date: Wed, 08 Aug 2001 20:51:10 -0800
>>>>
>>>>Raja,
>>>>if i do what you do..the value is same.
>>>>i am not sure if you said the value between v$sgastat and v$sga is
>>>>different.
>>>>
>>>>SVRMGR> select sum(value) from v$sga;
>>>>SUM(VALUE)
>>>>----------
>>>> 64046072
>>>>1 row selected.
>>>>SVRMGR> select sum(bytes) from v$sgastat;
>>>>SUM(BYTES)
>>>>----------
>>>> 64046072
>>>>1 row selected.
>>>>SVRMGR>
>>>>
>>>>Warm Regards,
>>>>
>>>>Hermanto P
>>>>Application Engineer
>>>>PT Riau Andalan Pulp And Paper - IT/IS Dept.
>>>>Phone : (0761) - 491147 / 491354
>>>>HP : 0812-752-3092
>>>>"Dream as if you'll live forever, live as if you'll die today"
>>>>
>>>>
>>>>
>>>>
>>>>-----Original Message-----
>>>>Sent: Thursday, August 09, 2001 11:30 AM
>>>>To: Multiple recipients of list ORACLE-L
>>>>
>>>>
>>>>Hello gurus,
>>>>
>>>>I am not able to understand 1 thing:-
>>>>
>>>>1. If I do :-
>>>>
>>>>select sum(bytes) from v$sgastat;
>>>>it gives me the SGA as :- 35041712
>>>>
>>>>2. But if I do :-
>>>>
>>>>select sum(value) from v$sga I get:- 35059816
>>>>
>>>>There is a difference of 18104 between 2 figures.
>>>>
>>>>Which 1 should I trust? which gives me the correct value of SGA?
>>>>
>>>>thanks
>>>>
>>>>rdgs,
>>>>
>>>>raja
>>>>
>>>>
>>>>Get 250 color business cards for FREE!
>>>>http://businesscards.lycos.com/vp/fastpath/
>>>>--
>>>>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>>>>--
>>>>Author: Viraj Luthra
>>>> INET: viraj999_at_lycos.com
>>>>
>>>>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
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>>>>the HELP command for other information (like subscribing).
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>>>>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>>>>--
>>>>Author: Hermanto P
>>>> INET: hermanto_p_at_aprilasia.com
>>>>
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>>>>San Diego, California -- Public Internet access / Mailing
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>>>>the HELP command for other information (like subscribing).
>>>
>>>
>>>_________________________________________________________________
>>>Get your FREE download of MSN Explorer at
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>>
>>
>>Get 250 color business cards for FREE!
>>http://businesscards.lycos.com/vp/fastpath/
>>--
>>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>>--
>>Author: Viraj Luthra
>> INET: viraj999_at_lycos.com
>>
>>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>>San Diego, California -- Public Internet access / Mailing Lists
>>--------------------------------------------------------------------
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>
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>>
>>
>>
>>
>>
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>>
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>>--
>>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>>--
>>Author: Girijan Puthran
>> INET: girijan.puthran_at_db.com
>>
>>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>>San Diego, California -- Public Internet access / Mailing Lists
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>
>
>Get 250 color business cards for FREE!
>http://businesscards.lycos.com/vp/fastpath/
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>--
>Author: Viraj Luthra
> INET: viraj999_at_lycos.com
>
>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>San Diego, California -- Public Internet access / Mailing Lists
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>
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>--
>Author: Jon Walthour
> INET: jonw_at_fuse.net
>
>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>San Diego, California -- Public Internet access / Mailing Lists
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Get 250 color business cards for FREE! http://businesscards.lycos.com/vp/fastpath/ -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Viraj Luthra INET: viraj999_at_lycos.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
Received on Sun Aug 12 2001 - 22:55:11 CDT

Original text of this message

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