Date: Sat, 21 Sep 2002 11:49:31 +0200 (CEST) From: Oliver Fromme <olli@secnetix.de> To: freebsd-stable@FreeBSD.ORG Subject: Re: Suggested modification to default install Message-ID: <200209210949.g8L9nVbu078908@lurza.secnetix.de> In-Reply-To: <87bs6sdqgd.fsf@pooh.int>
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Kirk Strauser <kirk@strauser.com> wrote: > At 2002-09-20T16:11:49Z, Brett Glass <brett@lariat.org> writes: > > In a thread earlier this year, it was noted that /stand/sysinstall, by > > default, sets most of the partitions it creates to use softupdates -- > > except for the root, which is mounted noasync without softupdates. This > > can lead to disaster if something on the root partition is being modified > > during a sudden crash. > > From 'man 8 mount': > > noasync > Metadata I/O should be done synchronously, while data I/O > should be done asynchronously. This is the default. > > In other words, 'noasync' == 'sync'. No, it's all different things: - noasync (which is the default if nothing else is specified) means that metadata I/O is done synchronously, and file data I/O is done asynchronously, as you quoted above. - sync means that _both_ metadata and file data I/O is done synchronously. - async means that _both_ metadata and file data I/O is done asynchronously. However, _neither_ of those three possibilities guarantee the consistency of the file system, not even "sync"! Only soft-updates will do that. For that reason, I see little value in mounting the root file system sync by default. I'd rather prefer to enable Soft-updates on it, too. (There's one problem with that during an installworld if there's little space left, but having too small a root filesystem is a bad idea anyway, and the problem will be fixed soon. I think it's already fixed in -current.) Regards Oliver -- Oliver Fromme, secnetix GmbH & Co KG, Oettingenstr. 2, 80538 München Any opinions expressed in this message may be personal to the author and may not necessarily reflect the opinions of secnetix in any way. "All that we see or seem is just a dream within a dream" (E. A. Poe) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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