Hi, I have a requirement (and a limited timeframe) to make a Windows 7 VM domain roll back to a fixed state on restart, shutdown etc. Something like a Kiosk Mode. I think this is a very needed part of the core of xen and this functionality does not appear to be part of xen already. So I''ve been trying various ways to make this work. Has anyone already implemented something like this successfully before? What I''ve been experimenting unsuccessfully with currently is the following: 1) Add hooks into the blktap2 code to roll back a VHD (currently based on the name ending in -persist.vhd). However, it''s not working out as it should. 2) Second attempt was to write an external script and call it periodically. The idea was to call vhd-snapshot on the parent disk to a new disk (temp name). Then do an atomic rename on existing vhd and unlink the old vhd. When it restarts you would think it would open up the new snapshot. Unfortunately, a reboot seems to detect that the file is different and so it''s not re-started as desired but instead the domain is shutdown. I don''t like either of the above methods. They are hacks in my opinion but I''m not currently familiar enough with xen internals. Can someone propose a method and/or suggest where I could hook into the xen tools to implement it? Regards, Matthew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi, Matthew Hook wrote:> I have a requirement (and a limited timeframe) to make a Windows 7 VM domain roll back to a fixed state on restart, shutdown etc. > Something like a Kiosk Mode. I think this is a very needed part of the core of xen and this functionality does > not appear to be part of xen already. So I''ve been trying various ways to make this work.XCP has a feature which might do what you need. If you are using .vhd file based storage (SR types ''ext'' or ''nfs'') then you can do the following: (for a VM called "myvm") # 1. Ensure the .vhd chain has length 2 (a current restriction) xe vm-copy vm=myvm new-name-label=nonpersistent.parent xe vm-clone vm=nonpersistent.parent new-name-label=nonpersistent # 2. Set the VDI on-boot=reset xe vm-disk-list vm=nonpersistent ... note the VDI uuid of the disk you want to reset ... xe vdi-param-set uuid=... on-boot=reset # 3. Start the VM xe vm-start vm=nonpersistent HTH, Dave
Thanks for that information. It isn''t obvious in the XCP code how this feature is being done and I''m not wanting to use XCP at this point as it''s behind without the latest hypervisor included. I actually created a patch where you can can set the temporary flag on the VHD features footer through vhd-util. Traditionally in the MS world is used to omdocated that the VHD can be removed on close. I''m using it for reset-on-boot where if the flag is set during _vhd_open it tests the flag and if set will regenerate the snapshot from the parent VHD. If anyone is interested in this patch right now I can send it through as is. However, I''ll submit it properly once I''ve done a bit more testing. Comments are welcome. Matt On 17 February 2012 13:21, Dave Scott <Dave.Scott@eu.citrix.com> wrote:> > Hi, > > Matthew Hook wrote: > > I have a requirement (and a limited timeframe) to make a Windows 7 VM domain roll back to a fixed state on restart, shutdown etc. > > Something like a Kiosk Mode. I think this is a very needed part of the core of xen and this functionality does > > not appear to be part of xen already. So I''ve been trying various ways to make this work. > > XCP has a feature which might do what you need. > > If you are using .vhd file based storage (SR types ''ext'' or ''nfs'') then you can do the following: (for a VM called "myvm") > > # 1. Ensure the .vhd chain has length 2 (a current restriction) > xe vm-copy vm=myvm new-name-label=nonpersistent.parent > xe vm-clone vm=nonpersistent.parent new-name-label=nonpersistent > > # 2. Set the VDI on-boot=reset > xe vm-disk-list vm=nonpersistent > ... note the VDI uuid of the disk you want to reset ... > xe vdi-param-set uuid=... on-boot=reset > > # 3. Start the VM > xe vm-start vm=nonpersistent > > HTH, > Dave