From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Reiser Subject: Re: Less disk space with reiser4? Date: Mon, 11 Apr 2005 13:22:04 -0700 Message-ID: <425ADC6C.8090209@namesys.com> References: <425A8A1D.9040206@siwnet.net> <20050411195253.GD6211@backtop.namesys.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: <20050411195253.GD6211@backtop.namesys.com> List-Id: Content-Type: text/plain; charset="us-ascii" To: Alex Zarochentsev Cc: Stefan Andersson , reiserfs-list@namesys.com Alex Zarochentsev wrote: >On Mon, Apr 11, 2005 at 04:30:53PM +0200, Stefan Andersson wrote: > > >>Hi, >> >>I have a disk array wich I used reiserfs(v3) on, and got 932G. >>Now I started to test reiser4 on it and get less space, 886G. >> >>Is it suppose to be like this or is there something wrong? >> >> > >reiser4 reserves 5% of disk space. > >That is so because of delayed block allocation impelented in reiser4. Actual >block allocation is done near the transaction commit, it means the allocation >has to be reliable -- we can't return ENOSPC because the write(2) call when we >could return an error was already completed successfully. > >The reserved space makes the allocation reliable because it covers possible >insertions (and growing of the internal reiser4 tree) of new extent items >insertions on a highly fragmented fs. > > It also improves performance to ensure that at least 5% is free. > > >>I'am using linux 2.6.11.4 and default settings for mkfs.reiser4 and >>mkfs.reiserfs, >>and reiser4 patch from 2.6.11-mm3. >> >>//Stetan >> >> >> > > >