Date: Mon, 09 Oct 2006 00:37:22 +0200 From: "Fluffles.net" <info@fluffles.net> To: freebsd-fs@FreeBSD.org Cc: Kris Kennaway <kris@obsecurity.org> Subject: Re: 2 bonnies can stop disk activity permanently Message-ID: <45297DA2.4000509@fluffles.net>
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Hi Bruce,
I'm the "veronica" Arne mentioned in the freebsd-fs mailinglist.
Regarding the effectiveness of a higher blocksize, these are my findings:
areca RAID5 (8x da, 128KB stripe, default newfs, NCQ enabled)
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU
/sec %CPU
ARC8xR5 8480 119973 91.3 247178 58.6 67862 17.5 90426 86.9 172490 24.0
120.7 0.5
areca RAID5 (8x da, 128KB stripe, 64KB blocksize newfs, NCQ enabled)
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU
/sec %CPU
ARC8xR5 8480 128920 97.8 265920 58.9 116787 31.0 103261 97.8 392970
53.8 119.8 0.6
As you can see, the block read increased from ~172MB/s to ~392MB/s,
quite significant increase. Also the reqrite speed increased from
~67MB/s to ~116MB/s.
Ofcourse these tests are on a brand clean filesystem, which might not
tally with real-life crowded filesystems. But at least there is much
potential in a higher blocksize, and it would be a shame for it to crash
FreeBSD. There are quite a few people who store big files on big RAID
arrays; they could profit from a non-crashing FreeBSD with bigger
blocksize. Besides, a crashing VFS/Geom isn't all that sexy. ;-)
- Veronica
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