Garrett Robinson
2010-Jul-12 03:28 UTC
[Xen-users] Support for file-based COW, present and future
I am currently working on a project that would be well-served by a file-based COW filesystem such as is theoretically offered by QCOW, according to both "Running Xen" and "The Book of Xen." Both books refer the reader to the internet for details on such an implementation. All I have been able to find so far is the COW section on the Xen wiki, which hasn''t been updated in three years, and various blog posts. Searching the xen-users archives only further diminished my hopes, as it seems like there are numerous bugs with the qcow implementation in Xen, and that the current unstable release of Xen is the only one with support in the first place. I know people on this forum are busy and that this is the somewhat general question of a newbie. What I''m really wondering is this: Has anybody has success with implementing COW filesystems for their Xen guests using any system, but in particular a file-based one? And does anybody know the present status or future of COW/QCOW implementation in Xen? Your time is greatly appreciated, Best, -Garrett Robinson. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Grant McWilliams
2010-Jul-12 07:11 UTC
Re: [Xen-users] Support for file-based COW, present and future
On Sun, Jul 11, 2010 at 8:28 PM, Garrett Robinson < Garrett.Robinson@oberlin.edu> wrote:> I am currently working on a project that would be well-served by a > file-based COW filesystem such as is theoretically offered by QCOW, > according to both "Running Xen" and "The Book of Xen." Both books refer the > reader to the internet for details on such an implementation. > > All I have been able to find so far is the COW section on the Xen wiki, > which hasn''t been updated in three years, and various blog posts. Searching > the xen-users archives only further diminished my hopes, as it seems like > there are numerous bugs with the qcow implementation in Xen, and that the > current unstable release of Xen is the only one with support in the first > place. > > I know people on this forum are busy and that this is the somewhat general > question of a newbie. What I''m really wondering is this: Has anybody has > success with implementing COW filesystems for their Xen guests using any > system, but in particular a file-based one? And does anybody know the > present status or future of COW/QCOW implementation in Xen? > > Your time is greatly appreciated, > Best, > -Garrett Robinson. >I fought with qcow and qcow2 with Xen for way too long. It seemed that no matter what version of Xen and the Linux kernel I was using there was always a bug that kept qcow from working. I eventually gave up. Rumor has it that Xen4 has working cow if you can get blktap2 to function. Grant McWilliams Some people, when confronted with a problem, think "I know, I''ll use Windows." Now they have two problems. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Fajar A. Nugraha
2010-Jul-12 07:48 UTC
Re: [Xen-users] Support for file-based COW, present and future
On Mon, Jul 12, 2010 at 2:11 PM, Grant McWilliams <grantmasterflash@gmail.com> wrote:> On Sun, Jul 11, 2010 at 8:28 PM, Garrett Robinson > <Garrett.Robinson@oberlin.edu> wrote: >> >> I am currently working on a project that would be well-served by a >> file-based COW filesystem such as is theoretically offered by QCOW,>> What I''m really wondering is this: Has anybody has >> success with implementing COW filesystems for their Xen guests using any >> system, but in particular a file-based one? And does anybody know the >> present status or future of COW/QCOW implementation in Xen?> I fought with qcow and qcow2 with Xen for way too long. It seemed that no > matter what version of Xen and the Linux kernel I was using there was always > a bug that kept qcow from working. I eventually gave up. Rumor has it that > Xen4 has working cow if you can get blktap2 to function.If you want to use copy-on-write file backingstore, I''d actually suggest using Xen 4. And even then it might be better to use vhd instead of qcow. http://wiki.xensource.com/xenwiki/blktap2 http://lxr.xensource.com/lxr/source/tools/blktap2/README Personally, I gave up trying to use qcow a long time ago, settling instead for storage-based COW functionality using zfs-fuse. -- Fajar _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Grant McWilliams
2010-Jul-12 07:59 UTC
Re: [Xen-users] Support for file-based COW, present and future
On Mon, Jul 12, 2010 at 12:48 AM, Fajar A. Nugraha <fajar@fajar.net> wrote:> On Mon, Jul 12, 2010 at 2:11 PM, Grant McWilliams > <grantmasterflash@gmail.com> wrote: > > On Sun, Jul 11, 2010 at 8:28 PM, Garrett Robinson > > <Garrett.Robinson@oberlin.edu> wrote: > >> > >> I am currently working on a project that would be well-served by a > >> file-based COW filesystem such as is theoretically offered by QCOW, > > >> What I''m really wondering is this: Has anybody has > >> success with implementing COW filesystems for their Xen guests using any > >> system, but in particular a file-based one? And does anybody know the > >> present status or future of COW/QCOW implementation in Xen? > > > I fought with qcow and qcow2 with Xen for way too long. It seemed that no > > matter what version of Xen and the Linux kernel I was using there was > always > > a bug that kept qcow from working. I eventually gave up. Rumor has it > that > > Xen4 has working cow if you can get blktap2 to function. > > If you want to use copy-on-write file backingstore, I''d actually > suggest using Xen 4. And even then it might be better to use vhd > instead of qcow. > > http://wiki.xensource.com/xenwiki/blktap2 > http://lxr.xensource.com/lxr/source/tools/blktap2/README > > Personally, I gave up trying to use qcow a long time ago, settling > instead for storage-based COW functionality using zfs-fuse. > > -- > Fajar > > _ >Have you ran into any pitfalls with zfs-fuse? Are you using it in production? I''m waiting for everyone else to beta test Xen4. It''s a little frustrating that qcow was never really finished because it isn''t like the code is proprietary or anything, it''s right there for the taking... Grant McWilliams Some people, when confronted with a problem, think "I know, I''ll use Windows." Now they have two problems. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Garrett Robinson
2010-Jul-12 14:43 UTC
Re: [Xen-users] Support for file-based COW, present and future
Thank you all for the replies. I was hoping to avoid wasting my time on a known pitfall, and unfortunately it appears that qcow and Xen 3.x are just such a dead end. I agree it is quite frustrating that it doesn''t work, as it''s functionality would be highly useful. I only wish I had the level of technical skill necessary to work on developing that support directly. Many thanks, -Garrett Robinson. On Mon, Jul 12, 2010 at 3:59 AM, Grant McWilliams < grantmasterflash@gmail.com> wrote:> > On Mon, Jul 12, 2010 at 12:48 AM, Fajar A. Nugraha <fajar@fajar.net>wrote: > >> On Mon, Jul 12, 2010 at 2:11 PM, Grant McWilliams >> <grantmasterflash@gmail.com> wrote: >> > On Sun, Jul 11, 2010 at 8:28 PM, Garrett Robinson >> > <Garrett.Robinson@oberlin.edu> wrote: >> >> >> >> I am currently working on a project that would be well-served by a >> >> file-based COW filesystem such as is theoretically offered by QCOW, >> >> >> What I''m really wondering is this: Has anybody has >> >> success with implementing COW filesystems for their Xen guests using >> any >> >> system, but in particular a file-based one? And does anybody know the >> >> present status or future of COW/QCOW implementation in Xen? >> >> > I fought with qcow and qcow2 with Xen for way too long. It seemed that >> no >> > matter what version of Xen and the Linux kernel I was using there was >> always >> > a bug that kept qcow from working. I eventually gave up. Rumor has it >> that >> > Xen4 has working cow if you can get blktap2 to function. >> >> If you want to use copy-on-write file backingstore, I''d actually >> suggest using Xen 4. And even then it might be better to use vhd >> instead of qcow. >> >> http://wiki.xensource.com/xenwiki/blktap2 >> http://lxr.xensource.com/lxr/source/tools/blktap2/README >> >> Personally, I gave up trying to use qcow a long time ago, settling >> instead for storage-based COW functionality using zfs-fuse. >> >> -- >> Fajar >> >> _ >> > Have you ran into any pitfalls with zfs-fuse? Are you using it in > production? I''m waiting for everyone else to beta test Xen4. It''s a little > frustrating that qcow was never really finished because it isn''t like the > code is proprietary or anything, it''s right there for the taking... > > > > Grant McWilliams > > Some people, when confronted with a problem, think "I know, I''ll use > Windows." > Now they have two problems. > > _______________________________________________ > 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
Garrett Robinson
2010-Jul-12 17:57 UTC
Re: [Xen-users] Support for file-based COW, present and future
Additionally, if anybody has any experience with Xen 4, positive or negative, to share, I would appreciate it, especially if you have any experience installing/using blktap2 or the VHD format. I am considering going all the way there myself; currently weighing the benefits of COW for this particular project I am working on. If I do decide to try Xen 4, I will post the results of my efforts. On Mon, Jul 12, 2010 at 10:43 AM, Garrett Robinson < Garrett.Robinson@oberlin.edu> wrote:> Thank you all for the replies. I was hoping to avoid wasting my time on a > known pitfall, and unfortunately it appears that qcow and Xen 3.x are just > such a dead end. I agree it is quite frustrating that it doesn''t work, as > it''s functionality would be highly useful. I only wish I had the level of > technical skill necessary to work on developing that support directly. > > Many thanks, > -Garrett Robinson. > > On Mon, Jul 12, 2010 at 3:59 AM, Grant McWilliams < > grantmasterflash@gmail.com> wrote: > >> >> On Mon, Jul 12, 2010 at 12:48 AM, Fajar A. Nugraha <fajar@fajar.net>wrote: >> >>> On Mon, Jul 12, 2010 at 2:11 PM, Grant McWilliams >>> <grantmasterflash@gmail.com> wrote: >>> > On Sun, Jul 11, 2010 at 8:28 PM, Garrett Robinson >>> > <Garrett.Robinson@oberlin.edu> wrote: >>> >> >>> >> I am currently working on a project that would be well-served by a >>> >> file-based COW filesystem such as is theoretically offered by QCOW, >>> >>> >> What I''m really wondering is this: Has anybody has >>> >> success with implementing COW filesystems for their Xen guests using >>> any >>> >> system, but in particular a file-based one? And does anybody know the >>> >> present status or future of COW/QCOW implementation in Xen? >>> >>> > I fought with qcow and qcow2 with Xen for way too long. It seemed that >>> no >>> > matter what version of Xen and the Linux kernel I was using there was >>> always >>> > a bug that kept qcow from working. I eventually gave up. Rumor has it >>> that >>> > Xen4 has working cow if you can get blktap2 to function. >>> >>> If you want to use copy-on-write file backingstore, I''d actually >>> suggest using Xen 4. And even then it might be better to use vhd >>> instead of qcow. >>> >>> http://wiki.xensource.com/xenwiki/blktap2 >>> http://lxr.xensource.com/lxr/source/tools/blktap2/README >>> >>> Personally, I gave up trying to use qcow a long time ago, settling >>> instead for storage-based COW functionality using zfs-fuse. >>> >>> -- >>> Fajar >>> >>> _ >>> >> Have you ran into any pitfalls with zfs-fuse? Are you using it in >> production? I''m waiting for everyone else to beta test Xen4. It''s a little >> frustrating that qcow was never really finished because it isn''t like the >> code is proprietary or anything, it''s right there for the taking... >> >> >> >> Grant McWilliams >> >> Some people, when confronted with a problem, think "I know, I''ll use >> Windows." >> Now they have two problems. >> >> _______________________________________________ >> 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
Fajar A. Nugraha
2010-Jul-13 01:28 UTC
Re: [Xen-users] Support for file-based COW, present and future
On Mon, Jul 12, 2010 at 2:59 PM, Grant McWilliams <grantmasterflash@gmail.com> wrote:> > On Mon, Jul 12, 2010 at 12:48 AM, Fajar A. Nugraha <fajar@fajar.net> wrote: >> Personally, I gave up trying to use qcow a long time ago, settling >> instead for storage-based COW functionality using zfs-fuse. >>> Have you ran into any pitfalls with zfs-fuse? Are you using it in > production?I''d consider it beta-quality. I use zfs-fuse in production, but not with Xen (where I only use it for dev purposes). If you''re considering using zfs for production then at this point I''d recommend having a separate server running NexentaStor/Solaris as storage server only.> I''m waiting for everyone else to beta test Xen4. It''s a little > frustrating that qcow was never really finished because it isn''t like the > code is proprietary or anything, it''s right there for the taking...There seems to be additional factors that made VHD support get higher priority http://community.citrix.com/display/ocb/2009/02/18/We''ve+Open+Sourced+Our+Optimized+VHD+Support -- Fajar _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users