Oracle block size

[Tim Medford]

We are installing Oracle 8.1.7 on a new HP L3000 server running HPUX 11.0.

We plan to use an 8K blocksize in Oracle (ie db_block_size = 8192).

I want to set the OS up to use 8k blocks as well. Is this simply the vps_pagesize kernel parameter or is there more to it?

Thanks, Tim

[Bruce Regittko_1]

Hi,

vps_pagesize sets the minimum page size for virtual memory, not disk I/O. I believe you set Oracle's extent size from within Oracle. Check out the following threads for more on Oracle block size:

http://forums.itrc.hp.com/cm/QuestionAnswer/1,1150,0xc9eb6c96588ad4118fef0090279cd0f9,00.html

http://my1.itrc.hp.com/cm/QuestionAnswer/1,1150,0xc9eb6c96588ad4118fef0090279cd0f9,00.html

http://forums.itrc.hp.com/cm/QuestionAnswer/1,1150,0x9bf26c96588ad4118fef0090279cd0f9,00.html

--Bruce

[Dave Wherry]

You'll want to set the block size when you create the file systems for your database:
newfs -F vxfs -b 8192 -o largefiles /dev/vg99/lvol99

[Steven Sim Kok Leong]

Hi,

The default block size for HFS is 8 kb. If you are intending to use HFS, you do not need to specify the block size explicitly ie. -b option is not required to be specified.

However, HFS is very much slower than JFS in database I/O operations such as tablespace creation. If you are using an Oracle block size of 8 kb, in general, you can improve I/O performance (especially in tablespace creation) by specifying an OS filesystem block size of 1 kb instead of 8 kb.

Hope this helps. Regards.

Steven Sim
Brainbench MVP for Unix Admin
http://www.brainbench.com

[Dan Hetzel · Accepted solution]

Hi Tim,

Adjusting the filesystem block size to match Oracle block size should give you the best possible database performance.

It's at the time of filesystem creation that you'll set the pagesize:
# newfs -F vxfs -b 8192 -o largefiles /dev/vg??/lvol?

vps_pagesize is unrelated to the disk I/O pagesize as it is the minimum pagesize for virtual memory.

Best regards,

Dan