Date: Sat, 19 Oct 2002 12:29:47 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: questions@FreeBSD.ORG Cc: Gabriel Ambuehl <gabriel_ambuehl@buz.ch> Subject: Re: softupdates on /? Message-ID: <20021019112947.GA66358@happy-idiot-talk.infracaninophi> In-Reply-To: <158158214781.20021019114034@buz.ch> References: <158158214781.20021019114034@buz.ch>
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On Sat, Oct 19, 2002 at 11:40:34AM +0200, Gabriel Ambuehl wrote:
> during the process of setting up some new servers I noticed that
> sysinstall will enable softupdates by default for everything BUT /.
> Is there any risk if I set / to use softupdates as well?
The problem with softupdates is that a modification to the contents of
a file system would result in a transient use of sufficient space to
contain both the old and new versions of all affected files. Normally
this is not a problem, but in certain cases it can lead to file
modifications failing because of a full filesystem even though there
is ultimately sufficient space available.
One common instance of this is doing a 'make installworld' or 'make
installkernel' where typical small root partitions generated by
sysinstall can be overflowed. Now, arguments about how large a root
partition should be or whether it should be amalgamated into /usr are
neither here not there, but the contents of a standard root partition
are generally static between major upgrades so there's no advantage to
be gained by turning softupdates on. (Nb. This assumes that /var and
/tmp are (sensibly) on different partitions to the root).
> It works, but I'm not sure about the possible implications of this...
For general use, softupdates on the root partition is not a problem.
If your root partition is big enough to let you do whatever you need
to by way of updating your system despite enabling softupdates, then
you can turn it on with impunity. Of course, the size of the contents
of the root partition tends to grow over time, so you may have to
revisit that decision later on.
It's also the case that modifications have been made to softupdates
that ameliorate this effect, certainly in 5-CURRENT, not sure if
they've been MFC'd to -STABLE though.
Cheers,
Matthew
--
Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks
Savill Way
Marlow
Tel: +44 1628 476614 Bucks., SL7 1TH UK
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