Re: File-syetem or Raw device

From: Steven Yu <stevenyu_at_mxic.com.tw>
Raw Partitions vs Regular File System

This topic has been covered a hundred times in the last year. There is no one right answer.

I like raw partitions. There is up to a 50% performance improvement on an individual I/O operation, but this only translates to about a 10% performance gain for your database as a whole. You can not use 'cp' or 'tar' to backup raw partations so you need to use 'dd'. The 'dd' command is not very bright, but if works well when passed input and output buffers for copying raw partitions. If you use tapes you are responsible for determining what will fit on a tape. If your UNIX system is short of memory, after converting to raw partitions the sysadmin can reconfigure UNIX to reduce the UNIX buffer pool since Oracle is no longer using it and this memory can be used to support Oracle or other processes.

A disadvantage is that raw partitions can not be expanded on the fly so dynamic file allocation is out. But I do not think that dynamic file allocation is appropriate for a production database anyway. A tablespace should never run out of room in a properly managed system; this can be a problem on when new improperly sized applications are turned on so it is a consideration.

Just thoughts.
Mark Powell -- The only advise that counts is the advise that you follow so follow your own advise Received on Wed Apr 23 1997 - 00:00:00 CDT