[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] COW in Xen
> Message: 3 > Date: Mon, 5 Mar 2007 20:41:56 +0200 > From: "Mark Ryden" <markryde@xxxxxxxxx> > Subject: [Xen-devel] COW in Xen > To: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx> > Message-ID: > <dac45060703051041g69aa83fax1d983a1959bd795c@xxxxxxxxxxxxxx> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Hello, > > I had posted this question in Xen-user mailing list three > days ago and I did not > get a single answer. On a second thought, maybe xen-devel is more > appropriate so > I am trying again in the hope that I will receive an answer: > > Does anybody have an experience (good or bad) with using > COW (Copy-On-Write) storage in Xen ? I've been using qcow images generated by qemu-img for Linux and MSWIndows HVM guests, and I've been getting good results. The image files are much smaller that the equivalently sized raw images. I simply create them (via gemi-img create -f qcom 10G) and use the disk=['file:...'] line in my guest configuration files. > > My question is : > There are some altenatives which are discussed in that wiki page: > unionfs, blktap ,using qemu: see > http://lxr.xensource.com/lxr/source/tools/blktap/, > BenRin's Copy-on-Write md device,Translucency , DmUserspace > ,parallax, CowNFS , and LVM snapshots (According to MichaelVrable wiki > as I understood it). > And BTW- does the XenFS has (or is intended to have) COW support ? > > What are the pros and cons of these options ? is there a preferred > one when using Xen ? I can't answer all the questions you've posted as I haven't experimented that much. The pros are smaller image files, the cons are those of the speed loss in a loopback file image, and mounting the file directly as a loopback within linux is a problem. The latter is possible I believe, but after playing with it a bit I had to move on to testing XEN... Curtis -- XEN of AMD Curtis W. Rendon _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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