Re: DB Block Size in Linux

I gather that I can choose the filesystem block size (perhaps during Linux installation). So I assume when I'm installing RehHat Linux 8 and selecting the ext2 filesystem to be the filesystem for that Linux installation, I would be able to choose a filesystem block size (I'd probably go 4k).

Then creating an Oracle9i database with a db block size larger than 4k (e.g. 8k) shouldn't be a problem since the filesystem buffer cache would cache a multiple of the filesystem blocks, in this case, a multiple of 4k blocks, meaning that an 8k database block size wouldn't induce any additional IO (behind the scenes) as I had feared before.

I'm a novice with Oracle+Linux so I hope I haven't over simplified this issue above.

"Noons" <wizofoz2k_at_yahoo.com.au.nospam> wrote in message news:<400287d6$0$4047$afc38c87_at_news.optusnet.com.au>...
> "Toby Brown" <toby_brown_at_optusnet.com.au> wrote in message news:2a84f50c.0401112041.4f55946f_at_posting.google.com...
>
>
> > is there any benefit at all in using an 8k default db block size for
> > an Oracle database on Linux, as opposed to a 4k block size? (of
> > course, I ask this question with the Linux file buffer cache size (4k)
> > in mind).
> >
>
> Toby, the Linux "file buffer cache size" is not 4K.
> The block size in Linux is highly dependent on the file
> system you're using. And even then, it's a tunable parameter.
>
> And the caching for that file system in the Linux file system cache
> will be in logical blocks of 4K but MUCH larger than just 4K!
> In fact it is variable, depending on how much free memory
> your system has.
>
> The most important thing you can do in Linux is match the database
> block size to what the file system block size is (or the other way
> around, if you have the luxury of creating the file systems from
> scratch).
>
> The second most important thing is to use freshly made file system(s)
> to create the database files in. And reduce the amount of other files
> (non-db) kept on file system(s) to an absolute minimum or 0.
>
>
> And if all else fails, use raw files rather than file system files.
> Then, the database will be the only user of those. And your upgrade
> to Oracle 10g will be so simple I can't even begin to describe how...
Received on Mon Jan 12 2004 - 18:22:53 CST