Re: FRA f/s block size
From: joel garry <joel-garry_at_home.com>
Date: Mon, 28 Mar 2011 09:55:26 -0700 (PDT)
Message-ID: <33d94693-169f-488f-8b99-a35959377f1c_at_j35g2000prb.googlegroups.com>
On Mar 27, 9:41 pm, Noons <wizofo..._at_gmail.com> wrote:
> 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...
Date: Mon, 28 Mar 2011 09:55:26 -0700 (PDT)
Message-ID: <33d94693-169f-488f-8b99-a35959377f1c_at_j35g2000prb.googlegroups.com>
On Mar 27, 9:41 pm, Noons <wizofo..._at_gmail.com> wrote:
> 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...
The docs seem to say Oracle uses different size buffers depending on your multiplexing http://download.oracle.com/docs/cd/E11882_01/backup.112/e10642/rcmtunin.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
-- _at_home.com is bogus. http://www.signonsandiego.com/news/2011/mar/24/barry-minkow-accused-stock-manipulation/Received on Mon Mar 28 2011 - 11:55:26 CDT