Date: Sun, 14 Oct 2001 21:10:05 -0700 From: Peter Wemm <peter@wemm.org> To: Matt Dillon <dillon@earth.backplane.com> Cc: "David O'Brien" <obrien@FreeBSD.ORG>, cvs-committers@FreeBSD.ORG, freebsd-arch@FreeBSD.ORG Subject: Re: cvs commit: src/sbin/newfs newfs.8 newfs.c Message-ID: <20011015041009.12A55380F@overcee.netplex.com.au> In-Reply-To: <200110150256.f9F2ur151690@earth.backplane.com>
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Matt Dillon wrote:
>
> :On Sun, Oct 14, 2001 at 04:03:03PM +0200, Ollivier Robert wrote:
> :> Speaking of changing that value, shouldn't we also change the default bloc
k
> :> and fragment values ?
> :>
> :> It has been said in the lists many times that 16k/2k is more efficient
> :> (and I'm using it myself by defautl now).
> :
> :There has been rummored problems if you use something other than 8k/1k.
> :This is probably something that should run thru -arch or -hackers before
> :doing it.
> :"-c" was a no-brainer as noone has ever argued that a low "-c" was
> :prefered (that I've seen).
>
> You can use 16K/2K safely. Anything larger may fragment the buffer
> cache's KVA space and create issues. There are no known bugs (other
> then fragmentation), but people have sporatically reported weirdness
> with other combinations. There have been no solid bug reports.
A ratio of 8:1 is the key for some reason. 4:1 used to regularly corrupt
news filesystems a couple of years ago. (we used 4k/1k).
Personally, I'm worried about using 16k/2k on anything less than a large (say
larger than 1G) file system.
If we made the defaults adjust to the fs size, I think that would be nice.
(ie: default to max -c possible, and switch to 16k/2k for "big" fs's)
Cheers,
-Peter
--
Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au
"All of this is for nothing if we don't go to the stars" - JMS/B5
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