From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Casier Subject: Re: Fwd: Fwd: [newstore (again)] how disable double write WAL Date: Tue, 16 Feb 2016 09:14:35 +0100 Message-ID: References: <9D046674-EA8B-4CB5-B049-3CF665D4ED64@aevoo.fr> <5661F3A9.8070703@redhat.com> <20151208044640.GL1983@devil.localdomain> <20160216033538.GB2005@devil.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from mail-wm0-f49.google.com ([74.125.82.49]:35776 "EHLO mail-wm0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754170AbcBPIOg (ORCPT ); Tue, 16 Feb 2016 03:14:36 -0500 Received: by mail-wm0-f49.google.com with SMTP id c200so147242966wme.0 for ; Tue, 16 Feb 2016 00:14:35 -0800 (PST) In-Reply-To: <20160216033538.GB2005@devil.localdomain> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Dave Chinner Cc: Ric Wheeler , Sage Weil , Ceph Development , Brian Foster , Eric Sandeen , =?UTF-8?Q?Beno=C3=AEt_LORIOT?= Hi, All inodes, xattrs and extent are stored at the beginning of the disk with inode32 XFS ? 2016-02-16 4:35 GMT+01:00 Dave Chinner : > On Mon, Feb 15, 2016 at 04:18:28PM +0100, David Casier wrote: >> Hi Dave, >> 1TB is very wide for SSD. > > It fills from the bottom, so you don't need 1TB to make it work > in a similar manner to the ext4 hack being described. > >> Exemple with only 10GiB : >> https://www.aevoo.fr/2016/02/14/ceph-ext4-optimisation-for-filestore/ > > It's a nice toy, but it's not something that is going scale reliably > for production. That caveat at the end: > > "With this model, filestore rearrange the tree very > frequently : + 40 I/O every 32 objects link/unlink." > > Indicates how bad the IO patterns will be when modifying the > directory structure, and says to me that it's not a useful > optimisation at all when you might be creating several thousand > files/s on a filesystem. That will end up IO bound, SSD or not. > > Cheers, > > Dave. > -- > Dave Chinner > dchinner@redhat.com -- ________________________________________________________ Cordialement, David CASIER 3B Rue Taylor, CS20004 75481 PARIS Cedex 10 Paris Ligne directe: 01 75 98 53 85 Email: david.casier@aevoo.fr ________________________________________________________