From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bernhard Duebi Subject: Re: btrfs defra Date: Fri, 17 Jun 2011 14:19:27 +0200 Message-ID: <1308313167.2504.157.camel@andromeda> References: <1307976637.2285.15.camel@andromeda> <20110613155420.GA14384@carfax.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Cc: Hugo Mills , linux-btrfs@vger.kernel.org To: David Nicol Return-path: In-Reply-To: List-ID: On Thu, 2011-06-16 at 08:50 -0500, David Nicol wrote: > > Defrag works on individual files, and tries to find a contiguous > > sequence of bytes to write the file's data to. In the process, the > > current implementation will break any CoW duplication -- either within > > single files (copies with cp --reflink=always) or files copied via > > snapshotting. > > > While it's obviously impossible to defrag and maintain deduplicated > partial chunks simultaneously without some kind of compromise (the > ideal form of which is just beyond the reach of this list > participant's obviousness flashlight), how difficult is it going to > be to modify the current defrag implementation to hip the additional > references to the file to the fact that a contiguous version (of an > individual file) is now available and it's time to update their links > too, after each file with multiple reflinks/snapshots to its current > form has been copied to contiguous space? > > Could Bernhard Duebi do it? Unfortunately not, I'm just a system engineer with interest in storage. I'm sorry to disapoint you. Sincerely Bernhard