Re: file system and raid performance

> -----Original Message-----
> From: Mark Wong [mailto:markwkm(at)gmail(dot)com]
> Sent: Thursday, August 07, 2008 12:37 PM
> To: Mario Weilguni
> Cc: Mark Kirkwood; greg(at)tcscs(dot)com; david(at)lang(dot)hm; pgsql-
> performance(at)postgresql(dot)org; Gabrielle Roth
> Subject: Re: [PERFORM] file system and raid performance
>

> I have heard of one or two situations where the combination of the
> disk controller caused bizarre behaviors with different journaling
> file systems. They seem so few and far between though. I personally
> wasn't looking forwarding to chasing Linux file system problems, but I
> can set up an account and remote management access if anyone else
> would like to volunteer.

[Greg says]
Tempting... if no one else takes you up on it by then, I might have some
time in a week or two to experiment and test a couple of things.

One thing I've noticed with a Silicon Image 3124 SATA going through a
Silicon Image 3726 port multiplier with the binary-only drivers from Silicon
Image (until the PM support made it into the mainline kernel - 2.6.24 I
think, might have been .25) is that under some heavy loads it might drop a
sata channel and if that channel happens to have a PM on it, it drops 5
drives. I saw this with a card that had 4 channels, 2 connected to a PM w/5
drives and 2 direct. It was pretty random.

Not saying that's happening in this case, but odd things have been known to
happen under unusual usage patterns.