From mboxrd@z Thu Jan 1 00:00:00 1970 From: jim owens Subject: Re: Thin provisioning & arrays Date: Tue, 11 Nov 2008 11:53:16 -0500 Message-ID: <4919B87C.8030100@hp.com> References: <28572.1226369378@ocs10w> <49198FC3.7080301@redhat.com> <49199CFF.8080002@hp.com> <4919A705.2070301@redhat.com> <4919ABC6.8030606@hp.com> <4919B1DD.3030207@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Keith Owens , Black_David@emc.com, david@fromorbit.com, dwmw2@infradead.org, martin.petersen@oracle.com, chris.mason@oracle.com, jens.axboe@oracle.com, James.Bottomley@hansenpartnership.com, linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, coughlan@redhat.com, matthew@wil.cx To: Ric Wheeler Return-path: Received: from g5t0007.atlanta.hp.com ([15.192.0.44]:14548 "EHLO g5t0007.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750757AbYKKQxT (ORCPT ); Tue, 11 Nov 2008 11:53:19 -0500 In-Reply-To: <4919B1DD.3030207@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Ric Wheeler wrote: > > I think that the concern is that the exact implementation is actually > already coded and relatively easy for us to do (i.e., send down unmap > commands at natural file system level units after a truncate/delete). > > The irony is that the hard part is to try to approach that level of > exactness with the other techniques (coalescing unmaps, defrag, etc) :-) I was using "exact" in the second sense... our battle about matching exactly with an array where the thin unmap chunk is greater than the natural file system level unit. Saying in that case, extreme measures are not justified. jim