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icon5.gif  all about db_block_size [message #223828] Sun, 11 March 2007 21:40 Go to next message
aftadel
Messages: 1
Registered: March 2007
Junior Member
hi there!!!

just like to ask importance of db_block_size... our oracle database db_block_size is 8192, while the OS block size is only 1024. what is the effect of this setting? does it have any effect on the performance of the database?

would appreciate experts' response on these...

thanks...

Re: all about db_block_size [message #224300 is a reply to message #223828] Tue, 13 March 2007 16:04 Go to previous messageGo to next message
nmacdannald
Messages: 460
Registered: July 2005
Location: Stockton, California - US...
Senior Member
I think you want your Oracle block size to be a multiple of your physical disk block size.

Larger block size works better when you find your database is doing full table scans or otherwise reading/writing large numbers of sequential blocks. The disadvantage of bigger blocks is that it needs to find room in the sga for your bigger blocks and it is harder to do that as the block size increases.

For a oltp, client/server where you are reading/writing little chunks of data smaller block sizes could be better. It is faster to find room in the sga when you are only looking for a small space.

The newer bigger Solaris machines have so much memory almost all of the database can be kept in memory, so block size is not as important.

[Updated on: Wed, 14 March 2007 12:42]

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Re: all about db_block_size [message #224520 is a reply to message #224300] Wed, 14 March 2007 09:22 Go to previous messageGo to next message
JRowbottom
Messages: 5933
Registered: June 2006
Location: Sunny North Yorkshire, ho...
Senior Member
I'm impressed. Our Db isn't terribly big, and it's got over 100Gb of datafile.
You've got that much ram on your system?
Re: all about db_block_size [message #224542 is a reply to message #224520] Wed, 14 March 2007 11:36 Go to previous message
nmacdannald
Messages: 460
Registered: July 2005
Location: Stockton, California - US...
Senior Member
Yes it has 32 gigs of memory and 8 processors which is larger than all our datafiles, indexes, archivelogs, ... the entire database and Oracle software. It serves only as a two tier Oracle database server. Only certain O/S's can handle a 'solid state' database because the o/s lies about actually writing dirty blocks to disk. It writes as fast as scii allowes but you MUST have a backup power supply to support solid state databases.
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