From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Reiser Subject: Re: journal size reiserfs vs reiser4 Date: Thu, 01 Sep 2005 10:59:18 -0700 Message-ID: <43174176.9010203@namesys.com> References: <20050901134604.31ddd297@SiRiUS.home> <20050901144842.34629bcf@SiRiUS.home> <4316F9CC.2090904@namesys.com> <20050901150507.3d6f53c7@SiRiUS.home> <4316FD28.5020304@redhat.com> <43171D57.3030007@namesys.com> <431726F2.1090508@redhat.com> <43173463.40302@slaphack.com> <43173A11.2000801@namesys.com> <43173C20.7070107@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <43173C20.7070107@redhat.com> List-Id: Content-Type: text/plain; charset="us-ascii" To: Peter Staubach Cc: David Masover , vs@namesys.com, reiserfs-list@namesys.com Peter Staubach wrote: > Hans Reiser wrote: > >>>>> >>>> >>>> Wow. What is all that space used for? Other journalling file >>>> systems that >>>> I have seen have limited things like journals to a much smaller space, >>>> >>> >> BSD FFS has a 10% limit unless you are root. They are correct to do so. >> > > Yes, they reserve that space so that their algorithms to choose blocks > from > the various cylinder groups can continue to choose blocks in decent > locations. > BSD FFS doesn't journal though. > > The SunOS UFS does journal metadata and retains the same 10% limit. > It was > discovered that the journal didn't need to be very big in order to > maximize > performance though. A very small log would do as well as a very large > log. Journaling, and reserving space for good allocation, are totally different concerns, I don't understand why you guys are conflating them. > > It would be interesting to pick a benchmark which represents some market > that usually deploys reiersfs and then experiment with various aspects of > the file system, including the reserve space. It is easy to do, mostly > just time consuming and requires a fair amount of resources. > > ps > >