Date: Sun, 27 Aug 2006 03:42:25 +0200 From: Daniel Gerzo <danger@FreeBSD.org> To: doc@freebsd.org Cc: Tom Rhodes <trhodes@FreeBSD.org>, Giorgos Keramidas <keramida@FreeBSD.org> Subject: mount(8) async description Message-ID: <2510186921.20060827034225@rulez.sk>
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Hello doc,
Milos Vyletel [mv(a)rulez.sk] noticed me about the current
description of the async flag for the mount -- we currently have:
async All I/O to the file system should be done asynchronously.
` This is a dangerous flag to set, and should not be used
unless you are prepared to recreate the file system
should your system crash.
Firstly, we thought that the last line is wrong, that
s/should/after/ would work, but I was told that the current version
is proper English.
But I still agree with Milos and I don't like the current
description, therefore I produced a patch which says:
async All I/O to the file system should be done asynchronously.
This is a dangerous flag to set, although it increases
I/O performance. When this option is used, it is not
guaranteed to keep a consistent file system structure on
the disk, and it is impossible to verify the integrity of
data. It should be used only if some application-spe-
cific data recovery mechanism is present, or recreation
of the file system is not a problem.
I passed this through my mentors, it was OK'd by Tom, but Giorgos
says it's too wordy and he likes NetBSD's description:
async All I/O to the file system should be done asyn-
chronously. In the event of a crash, it is
impossible for the system to verify the integrity of
data on a file system mounted with this option. You
should only use this option if you have an applica-
tion-specific data recovery mechanism, or are willing
to recreate the file system from scratch.
To be complete, OpenBSD has:
async All I/O to the file system should be done asynchronously.
This is a dangerous flag to set since it does not guaran-
tee to keep a consistent file system structure on the
disk. You should not use this flag unless you are pre-
pared to recreate the file system should your system
crash. The most common use of this flag is to speed up
restore(8) where it can give a factor of two speed in-
crease.
Giorgos told me to go through doc@ and ask what other people think.
So here it is. What do you think about my description? Would you
accept it, or should I trim it a bit? Or just pick the NetBSD's one
and commit?
--
Best regards,
Daniel mailto:danger@FreeBSD.org
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