All, I have asked this question before about COW backed VBD support in Xen. It would be really cool if I could share the same root FS between domains, each having its own COW system. I am typically using file-backed roots. Does Xen (as User-mode linux) provide utility to create COW disks (linked to a readOnly main disk) which can be used as VBDs. Arijit _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> I have asked this question before about COW backed VBD support in Xen. It > would be really cool if I could share the same root FS between domains, > each having its own COW system.Indeed.> I am typically using file-backed roots. Does Xen (as User-mode linux) > provide utility to create COW disks (linked to a readOnly main disk) which > can be used as VBDs.You can use LVM2 snapshots or the Device Mapper to create a COW virtual device. LVM, at least, seems to have some issues with scalability when doing lots of CoW-ing though - make sure dom0 has enough memory. The other way of doing things is CoW at the filesystem, rather than at block level. E.g. combine NFS and UnionFS or use a CoW NFS server (someone in Cambridge developed one but I don''t know if the code is floating around). I''ll be working on a CoW filesystem also, later this year. Cheers, Mark _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> or use a CoW NFS server (someone in > Cambridge developed one but I don''t know if the code is floating around).If you happen accross it I''d love to see it :)> I''ll be working on a CoW filesystem also, later this year.Great to hear Mark. I''ll be looking forward to it. :) Cheers, John Fairbairn>> I have asked this question before about COW backed VBD support in Xen. >> It >> would be really cool if I could share the same root FS between domains, >> each having its own COW system. > > Indeed. > >> I am typically using file-backed roots. Does Xen (as User-mode linux) >> provide utility to create COW disks (linked to a readOnly main disk) >> which >> can be used as VBDs. > > You can use LVM2 snapshots or the Device Mapper to create a COW virtual > device. LVM, at least, seems to have some issues with scalability when > doing > lots of CoW-ing though - make sure dom0 has enough memory. > > The other way of doing things is CoW at the filesystem, rather than at > block > level. E.g. combine NFS and UnionFS or use a CoW NFS server (someone in > Cambridge developed one but I don''t know if the code is floating around). > I''ll be working on a CoW filesystem also, later this year. > > Cheers, > Mark > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > or use a CoW NFS server (someone in > > Cambridge developed one but I don''t know if the code is floating around). > > If you happen accross it I''d love to see it :)I''ll ask around...> > I''ll be working on a CoW filesystem also, later this year. > > Great to hear Mark. I''ll be looking forward to it. :)Lots to do yet but if it all works out it should be way kewl. The only trouble is it requires lots of coding to happen first :-) I doubt I''ll ever match the coolness of a UML CoW disk command I remember seeing - something like "cow_moo" :-D Cheers, Mark> Cheers, > John Fairbairn > > >> I have asked this question before about COW backed VBD support in Xen. > >> It > >> would be really cool if I could share the same root FS between domains, > >> each having its own COW system. > > > > Indeed. > > > >> I am typically using file-backed roots. Does Xen (as User-mode linux) > >> provide utility to create COW disks (linked to a readOnly main disk) > >> which > >> can be used as VBDs. > > > > You can use LVM2 snapshots or the Device Mapper to create a COW virtual > > device. LVM, at least, seems to have some issues with scalability when > > doing > > lots of CoW-ing though - make sure dom0 has enough memory. > > > > The other way of doing things is CoW at the filesystem, rather than at > > block > > level. E.g. combine NFS and UnionFS or use a CoW NFS server (someone in > > Cambridge developed one but I don''t know if the code is floating around). > > I''ll be working on a CoW filesystem also, later this year. > > > > Cheers, > > Mark > > > > _______________________________________________ > > Xen-users mailing list > > Xen-users@lists.xensource.com > > http://lists.xensource.com/xen-users > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users