From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Zarochentsev Subject: Re: Less disk space with reiser4? Date: Mon, 11 Apr 2005 23:52:53 +0400 Message-ID: <20050411195253.GD6211@backtop.namesys.com> References: <425A8A1D.9040206@siwnet.net> Mime-Version: 1.0 Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com Content-Disposition: inline In-Reply-To: <425A8A1D.9040206@siwnet.net> List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Stefan Andersson Cc: reiserfs-list@namesys.com 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. > 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 > -- Alex.