From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4798705C.4080802@wpkg.org> Date: Thu, 24 Jan 2008 12:02:52 +0100 From: Tomasz Chmielewski MIME-Version: 1.0 Subject: Re: [linux-lvm] Re: [RFC] Multiple Snapshots - Manageability problem References: <4797686A.4000306@wpkg.org> In-Reply-To: Content-Transfer-Encoding: 7bit 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: LVM general discussion and development Cc: dm-devel@redhat.com Dan Kegel schrieb: > On Jan 23, 2008 8:16 AM, Tomasz Chmielewski wrote: >> Vijai Babu Madhavan, Thu, 11 Jan 2007 11:18:13 -0700, wrote: >> >>> The problem of DM snapshots with multiple snapshots have been discussed >>> in the lists quiet a bit (Most recently @ >>> https://www.redhat.com/archives/dm-devel/2006-October/msg00034.html). >>> >>> We are currently in the process of building a DM snapshot target that scales >>> well with many snapshots (so that the changed blocks don't get copied to each >>> snapshot). In this process, I would also like to validate an assumption. >> Any news on that? >> >> Still, with multiple snapshots write performance degrades linearly - is >> any work done to change that anytime soon? > > Yes. Dan Phillips has implemented a shared snapshot exception store. > You can try it out now if you like; it's at http://zumastor.org. > It feels a bit different from the user's point of view than LVM, though. > It plays well with the device mapper and can be used with any > block device (LVM or non-LVM). Does it use device mapper (or it just "plays well with the device mapper")? Or is it a totally different technology? I didn't find it explained very clearly in Zumastor HOWTO on http://zumastor.googlecode.com/svn/trunk/doc/zumastor-howto.html (other than pointers to /dev/mapper/zumatest, which probably means it uses device mapper). -- Tomasz Chmielewski http://wpkg.org