Hi gang.

I haven't seen this one discussed anywhere and can't really find any
references
to it that are worth repeating.

Does anyone have any information on optimal file system block sizes
for FRA?
As in: the area where one keeps RMAN backups and archived redo log
backups?

Specifically, in my case: in 10gr2, 11gr2, Aix 5.3 and 6.1, using
jfs2.

I've got my development node with an FRA file system with 512 byte
block size.
And production is on 4096 - max for jfs2.

I haven't been able to prove conclusively that one is better than the
other for
normal RMAN backup/restore operations.

Any accumulated wisdom/advice/experience on this?

Nope: I couldn't find a button for this in OEM or grid, either...

On Mar 27, 9:41*pm, Noons <wizofo... (AT) gmail (DOT) com> wrote:
The docs seem to say Oracle uses different size buffers depending on
your multiplexing http://download.oracle.com/docs/cd/E...n.htm#BABDCIHI
but I would guess the OS characteristics would have a greater effect.
Is AIX strange? I'd speculate you could force a visible effect doing
something like restoring a whole bunch of single blocks with Oracle
using a small buffer and the OS using a large one, getting lots of
extra unnecessary blocks from the OS to discard. Everything else
would likely mask effects because you are streaming lots of blocks
sequentially, no? Well, maybe if you are blasting out lots of blocks
onto a device with heavily hit random access data files...

jg
--
@home.com is bogus.
http://www.signonsandiego.com/news/2...-manipulation/

joel garry wrote,on my timestamp of 29/03/2011 3:55 AM:

Yup, makes sense.

Man, is it ever! Weirdest Unix I've ever seen.
And I don't mean that in a bad way:
there's a lot of good stuff about Aix and Power6.


My guess is that jfs2 and/or Oracle will stream together a lot of small I/Os
into a scatter/gather type operation that won't be much affected by the file
system blocksize. As such it won't matter much if I got 512 or 4096,
performance-wise. Except for the last I/O in a stream, and that won't be much
overall anyway. Provided as you say I'm not colliding with other types of I/O.
Which I'm not: this f/s is dedicated to FRA, on its own SAN LUN.
Likely as well why I am not seeing any differences between 512 and 4096?

Still: all speculation. I'll try and strace something to see if I can figure
out what the heck is going on at the coal face. Will report back here.