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How does block size of the FS affect the SAP server

kenken_3
Regular Advisor

How does block size of the FS affect the SAP server

Hi,

We have SAP application and oralce DB running on our RP7440 server, the OS version is HPUX11.11.

Currently the SAP team told us that the block size of FS of the SAP datafiles should be 8k and the rest like redo log and achieve log FS should be 1k.

Anyone knows about this? and why?

thanks,
wang & wang
4 REPLIES
Mark McDonald_2
Trusted Contributor

Re: How does block size of the FS affect the SAP server

Depends on how they have the tables set up, and how they are writing the data across the stripes. You will probably find they are writing 8k or 1k blocks of data, this will help with performance.

Avinash20
Honored Contributor

Re: How does block size of the FS affect the SAP server

Please refer to the following url which talks about how to choose the block size

http://docs.hp.com/en/B3929-90011/ch05s02.html

For oracle DB:
http://www.ixora.com.au/notes/log_block_size.htm

http://www.ixora.com.au/notes/redo_wastage.htm

"Light travels faster than sound. That's why some people appear bright until you hear them speak."
Avinash20
Honored Contributor

Re: How does block size of the FS affect the SAP server

The fs uses an 8kb fs block size. This needs to match the Oracle block size if you want to do efficient direct I/O. So if you keep the Oracle block size at 4k or less, you need to change the fs block size to 4kb. For best results, it should match. We would suggest 8kb for the FS block size and 8kb for the Oracle block size which is what the majority of our customers do. The exception is that a 16Kb or larger Oracle block size can use a FS block size of 8kb.

Put the archive and redo logs on separate filesystems with 1kb filesystem block size and mounted for Direct I/O(In case if you have Online JFS installed)
"Light travels faster than sound. That's why some people appear bright until you hear them speak."
kenken_3
Regular Advisor

Re: How does block size of the FS affect the SAP server

the thread is closed.
wang & wang