Date: Wed, 18 Jan 2006 12:35:29 -0500 (EST) From: Ensel Sharon <user@dhp.com> To: freebsd-hackers@freebsd.org Subject: tuning to run large (1000+) numbers of null_mounts Message-ID: <Pine.LNX.4.21.0601181228590.8684-100000@shell.dhp.com>
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I am running over 2000 null mounts on a FreeBSD 6.0-RELEASE system. I am
well aware of the status of the null_mount code, as advertised in the
mount_nullfs man page:
THIS FILE SYSTEM TYPE IS NOT YET FULLY SUPPORTED (READ: IT DOESN'T
WORK)
AND USING IT MAY, IN FACT, DESTROY DATA ON YOUR SYSTEM. USE AT YOUR
OWN
RISK. BEWARE OF DOG. SLIPPERY WHEN WET.
So, based on this, all of my null_mounts are actually mounted read-only.
I am noticing both system instability and data corruption issues on disk
following crashes. Both of these seem to be related to the null
mounts. I have two very quick questions:
1. Is my theory that using only read-only null mounts is a good way to
avoid data corruption a sound one ? Or can even a read-only null mount do
bad things to underlying data ?
2. What system tunes / alterations would be appropriate for a system
running several thousand (although, always less than 5000) null mounted
filesystems ?
Please relay _any and all_ comments, suggestions, war stories,
rumors. They are very appreciated.
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