From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Mon, 29 Oct 2007 14:26:58 -0700 (PDT) Received: from larry.melbourne.sgi.com (larry.melbourne.sgi.com [134.14.52.130]) by oss.sgi.com (8.12.11.20060308/8.12.10/SuSE Linux 0.7) with SMTP id l9TLQnBV012360 for ; Mon, 29 Oct 2007 14:26:52 -0700 Date: Tue, 30 Oct 2007 08:26:49 +1100 From: David Chinner Subject: Re: Default mount options (that suck less). Message-ID: <20071029212649.GL995458@sgi.com> References: <20071029075657.GA84369978@melbourne.sgi.com> <20071029085502.GI995458@sgi.com> <4725E7D0.8090400@sandeen.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4725E7D0.8090400@sandeen.net> Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Eric Sandeen Cc: David Chinner , Niv Sardi , xfs@oss.sgi.com On Mon, Oct 29, 2007 at 09:01:52AM -0500, Eric Sandeen wrote: > David Chinner wrote: > > On Mon, Oct 29, 2007 at 06:56:57PM +1100, Niv Sardi wrote: > >> Hello, > >> > >> XFS's default mount options are in most cases sub-optimal, we should try > > > > Mkfs options ;) > > > >> to have more sensible defaults, so far I'm following some quick dave-powered > >> recomendations: > >> > >> - version 2 logs > >> - attr2 > >> - lazy superblock counters > >> - less allocation groups for single disk configs > >> > >> - imaxpct default can be reduced > >> > >> it is currently 25, what would be reasonable ? > > > > Given that 25% on a 4GB filesystem will allow about 5million inodes, > > I think it's probably reasonable to bring it down to 5% by the time we > > pass 1TB and 1% by 50TB..... > > But what does this affect? It's a cap, but it doesn't affect allocation > policy or anything does it? What's the downside to 25%? It reserves allocation groups as "metadata only" for inode32 filesystems so data doesn't get placed in them untill all other space is full. So at 1TB, we don't use 25% of the filesystem until the other 75% is full, yet to hold 4 million inodes we only need about 1GB of space. so 5GB out of 1TB gives us space in the filesystem for ~20m million inodes by default. AFAICT, this is the only place it is used. Likewise, at 50TB, we're only going to be able to use 2% of the filesystem for inodes with inode32. At 100TB, it's meaningless..... Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group