From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx13.extmail.prod.ext.phx2.redhat.com [10.5.110.18]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q1GG4IOb008182 for ; Thu, 16 Feb 2012 11:04:18 -0500 Received: from qmta07.westchester.pa.mail.comcast.net (qmta07.westchester.pa.mail.comcast.net [76.96.62.64]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q1GG49D4017342 for ; Thu, 16 Feb 2012 11:04:10 -0500 Message-ID: <4F3D28F8.2060009@mohawksoft.com> Date: Thu, 16 Feb 2012 11:04:08 -0500 From: Mark Woodward MIME-Version: 1.0 References: <4F3D03AE.2050502@mohawksoft.com> <20120216135702.GA6212@redhat.com> <4F3D15CC.1080901@mohawksoft.com> <20120216154301.GA13948@redhat.com> In-Reply-To: <20120216154301.GA13948@redhat.com> Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] Snapshots Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Mike Snitzer Cc: LVM general discussion and development On 02/16/2012 10:43 AM, Mike Snitzer wrote: > On Thu, Feb 16 2012 at 9:42am -0500, > Mark Woodward wrote: > >> On 02/16/2012 08:57 AM, Mike Snitzer wrote: >>> On Thu, Feb 16 2012 at 8:25am -0500, >>> Mark Woodward wrote: >>> >>>> I have been looking into LVM2 for a while now and while I think it >>>> is useful for a range of applications, its seems pretty limited in >>>> overall scope. >>>> >>>> Is there any active development happening? Most of the code seems >>>> like bug-fixes or minor tweaks. Is the snapshot system being >>>> improved? Specifically, snapshots of snapshots? thin provisioned >>>> snapshots or auto-expand (i.e. snapshots don't run out of space). >>>> If you look at technologies like ZFS snapshots are far better >>>> supported, but ZFS will probably never be real under Linux, and it >>>> really is far more than is really needed. >>>> >>>> So, I guess my questions are these: Is LVM in maintenance mode or is >>>> there active development? If it is being actively developed, is >>>> there a road map and is there a group or site specifically dedicated >>>> to the development? >>> Um, where are you even getting this idea that LVM2 is in maintenance >>> mode? Or that snapshots haven't improved? >>> >>> Sorry to come off defensive but your entire post is founded on incorrect >>> understanding. >> Understood, I apologize. >>> Anyway, if you look at the change history of the lvm2 repository (be it >>> cvs or git, cvs commits are mirrored to git) you'll see there have been >>> regular changes flowing in and most recently a very extensive evolution >>> of the code to add support for thin provisioning with highly efficient >>> snapshots (ala btrfs or ZFS). >> I guess I missed that. I need to check out the changes, looks like >> you have auto-grow with monitoring? I was looking more towards the >> "snapshots of snapshots" ability. Is that on the radar? > recursive snapshots of arbitrary depth (snapshot of snapshots ...) are > already supported with the new thinp snapshots. > > Please review the upstream Linux>= 3.2 kernel code/docs too, it has > more documentation of the underlying capabilities, e.g.: > > Documentation/device-mapper/thin-provisioning.txt > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=Documentation/device-mapper/thin-provisioning.txt > > (the "Introduction" being the most approachable overview) OK, that's where I missed it. I looked at the snapshots description. It is now part of thin-provisioning. Got it. Will it be in the 2.6 kernel or will there need to be an upgrade to 3.x series?