From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ric Wheeler Subject: Re: thin provisioned LUN support & file system allocation policy Date: Fri, 07 Nov 2008 11:02:46 -0500 Message-ID: <491466A6.6020903@redhat.com> References: <4913028B.6010405@redhat.com> <1225984628.4703.80.camel@localhost.localdomain> <20081107120534.GO21867@kernel.dk> <49143142.4010809@redhat.com> <20081107121934.GP21867@kernel.dk> <49145029.4040900@redhat.com> <20081107144311.GE9543@mit.edu> <4914568A.7090307@redhat.com> <49145E0C.4030705@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Theodore Tso , Jens Axboe , Chris Mason , Dave Chinner , David Woodhouse , James Bottomley , linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, Black_David@emc.com, "Martin K. Petersen" , Tom Coughlan , Matthew Wilcox To: jim owens Return-path: Received: from mx2.redhat.com ([66.187.237.31]:60458 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752265AbYKGQDb (ORCPT ); Fri, 7 Nov 2008 11:03:31 -0500 In-Reply-To: <49145E0C.4030705@hp.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: jim owens wrote: > Ric Wheeler wrote: > >> The type of allocation that would help most is something that tries >> to keep the lower block ranges "hot" for allocation, second best >> policy would simply keep the allocated blocks in each block group hot >> and re-allocate them. > > This block reuse policy ignores the issue of wear leveling... > as in most design things, trading one problem for another. > > jim Wear levelling is not a problem for all (most?) T10 unmap capable arrays since they remap pretty much everything internally, Ric