Re: raw partions vs file systems

I do not have numbers on FS vs Raw.

Each access to data on filesystem must interact with the filesystem overhead (inode traversal and levels of indirection). In a commonly accessed file, this may not be a huge issue as this information will be cached by the OS - which can be a problem on writes if the system goes down as data may be lost (this is why we have fsck).

You should consider that the memory being used by the OS to cache these disk pages might be better used if you were to instead use raw devices and allocate that extra memory directly to the SGA.

If you are using raw devices you need not lose any sleep wondering if when you told the filesystem to write to disk, if it really did. The potential lose in performance of each write to disk rather than caching in the OS can be overcome by installing some battery backed up cache on the disk.

-Chris

Mick McRae wrote:

> Hi,
>
> I've only ever configured Oracle databases using Unix file systems. A
> site
> I'm starting with uses raw partitions. Do raw partitions provide
> significant performance increases? I suppose the performance gain would
> want to be
> at least 10% for the additional overhead and limited flexibility of
> using raw partions.
>
> We run Oracle7/Oracle8 on Solaris 2.5.1/2.6. As a scenario, assume a
> 5GB
> and 10GB database. Also, what are the differences if the database is
> predominantly read-only as opposed to write intensive. The
> filesystems/rawpartions are striped and mirrored, although this does not
>
> necessarily have to be the case.
>
> Any input appreciated
>
> Regards,
> Mick
Received on Sun Sep 27 1998 - 12:05:49 CDT