Date: Thu, 23 Feb 2006 18:00:05 +1100 From: Peter Jeremy <peterjeremy@optushome.com.au> To: Miguel Lopes Santos Ramos <miguel@anjos.strangled.net> Cc: rossiya@gmail.com, freebsd-stable@freebsd.org Subject: Re: Remote tunefs -n enable Message-ID: <20060223070005.GA688@turion.vk2pj.dyndns.org> In-Reply-To: <200602221003.k1MA3ixi001559@compaq.anjos.strangled.net> References: <28a99ba50602212307g48db9a53m322fba44eb315a17@mail.gmail.com> <200602221003.k1MA3ixi001559@compaq.anjos.strangled.net>
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On Wed, 2006-Feb-22 10:03:44 +0000, Miguel Lopes Santos Ramos wrote: >> From: MC <rossiya@gmail.com> >> Consequently he hasn't set softupdates on the main '/' partition > >It wasn't his fault. It is the default install option. >You see, root is mainly a read file system. Typical writes are a kernel >install (not too important to optimize) and updating configuration files >(it shouldn't be so often). The real reason is that there is a "bug" in softupdates which means that space freed up by deleting a file is not available for allocation for about 30 seconds. (Fixing this is non-trivial). The root file- system is traditionally relatively small and a substantial portion of it is re-written during installworld and installkernel, leading to a non-trivial likelihood that you could get a false "filesystem full" message. >Furthermore, if one can avoid any risky operation on /, all the better. >I think that's why the option for / is using synchronous writes without Actually, / uses traditional Unix semantics - synchronous metadata updates (inodes and directories) and asynchronous data updating. >I think the filesystem must be unmounted to enable softupdates. One approach would be to stick a script into /etc/rc.d that executes early (before root is made R/W) to run "tunefs -n enable ..." and then delete the script after rebooting. -- Peter Jeremy
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