Date: Wed, 12 Feb 2003 21:19:52 -0800 From: David Schultz <dschultz@uclink.Berkeley.EDU> To: Brooks Davis <brooks@one-eyed-alien.net> Cc: Terry Lambert <tlambert2@mindspring.com>, Darren Pilgrim <dmp@pantherdragon.org>, Matthew Emmerton <matt@gsicomp.on.ca>, Daxbert <daxbert_news@dweebsoft.com>, Bill Moran <wmoran@potentialtech.com>, Heinrich Rebehn <rebehn@ant.uni-bremen.de>, freebsd-questions@FreeBSD.ORG, freebsd-fs@FreeBSD.ORG Subject: Re: Why is there no JFS? Message-ID: <20030213051952.GA11572@HAL9000.homeunix.com> In-Reply-To: <20030212210721.A9481@Odin.AC.HMC.Edu> References: <3E4A8EF5.1070308@ant.uni-bremen.de> <3E4A9712.8030609@potentialtech.com> <3E4AA331.5040701@ant.uni-bremen.de> <3E4AA734.5040102@potentialtech.com> <045401c2d2db$f9d45c30$0a0aa8c0@dweebsoft.com> <20030212225631.GA10375@HAL9000.homeunix.com> <005801c2d2eb$aa5fae60$1200a8c0@gsicomp.on.ca> <3E4ADDDE.5040208@pantherdragon.org> <3E4B138F.26E32E75@mindspring.com> <20030212210721.A9481@Odin.AC.HMC.Edu>
next in thread | previous in thread | raw e-mail | index | archive | help
Thus spake Brooks Davis <brooks@one-eyed-alien.net>: > On Wed, Feb 12, 2003 at 07:40:00PM -0800, Terry Lambert wrote: > > Darren Pilgrim wrote: > > > Not really. A properly laid-out filesystem hierarchy will result in no > > > writes to / (except for installworld/kernel). That removes the problem > > > that journalling addresses, and is probably why softupdates is disabled > > > by default for /. For large, active filesystems, journalling would be a > > > big improvement when you had to run a foreground fsck. > > > > Soft updates are disable on / by default because of the chicken > > and egg problem of runing tunefs on /. > > There's no chicken and egg problem when you're booting off install > media or for that matter from single user mode. The problem was that > softupdates means you don't get space back from deleted files immediatly > so previously / tended to fillup during installworld or installkernel. > I know some fixes have been implemented in that area, but I'm not sure > if then mean you can always write to the space occupied by unlinked > files or just that you have a better chance. The problem is effectively fixed in 5.0. Basically, when no space can be found, the syncer is accelerated to try to speed up frees. Technically it's possible to run into a livelock, where you keep freeing space and it keeps getting snatched up before you can grab it, so you wait forever. So IIRC, there is a point where it just gives up on finding the space. However, that won't happen with an install, so the free space problem isn't a reason not to use softupdates on the root FS. I think the default hasn't been changed just because nobody has bothered. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20030213051952.GA11572>