Re: [Xen-users] Re: Accessing an LV domU

[Andris <andris@xxxxxxxx>]

Simone wrote:
> Hi again,
>
> I am afraid I will have to ask fro more advice. I have followed the
> suggestions, basically:
>
> Created an LV /dev/XenVG/qanew and /dev/XenVG/qanew_swap (no
> filesystem created on it)
>
> in the conf file for the VM I have:
>
> disk = [ 'phy:XenVG/qanew,xvda,w', 'phy:XenVG/qanew_swap,xvdb,w' ]
>
> I create only one partition xvda1 mounted as / and filesystem ext3
> while xvdb1 is used as swap, and GRUB is installed on MBR
>
> Once the installation is done and the VM is not on, I try to mount
> /dev/XenVG/qanew on /opt/test but it complains I need to specify
> filesystem, if I run mount -t ext3 .... it complains it is not an ext3
> filesystem.
>
> I have been on the net trying to understand where i am going wrong but
> can't seem to find any valid solution.
>
> Any further help would be much appreciated.
>
> Thanks,
>
> Simone
>
>
> On Mon, Mar 31, 2008 at 11:19 AM, Simone <dezmodue@xxxxxxxxx
> <mailto:dezmodue@xxxxxxxxx>> wrote:
>
>     Thanks all for your replies.
>
>     Considering the trouble I would have to go through and the fact
>     that I don't need snapshotting within the VM, I am moving to a
>     simpler configuration as suggested.
>
>     Thanks again,
>
>     Simone
>
>
>     On Mon, Mar 31, 2008 at 2:49 AM, Jayson Charles Vantuyl
>     <jvantuyl@xxxxxxxxxxxxxx <mailto:jvantuyl@xxxxxxxxxxxxxx>> wrote:
>
>         It's not so unusual.  It just wasn't easy to come across
>         before widespread virtualization.
>
>         Nesting LVM setups like this CAN be done, but generally
>         shouldn't.
>
>         Essentially, LVM works by detecting the physical volumes that
>         are part of the LVM.  Since you are setting up an LVM that is
>         effectively on another LVM device, the detection can get
>         weird--especially if you name an inner LVM volume group the
>         same name as an external LVM volume group.  Let's just say
>         that mixing LVM data from the inner and outer devices can
>         happen, and then things can get really broken.
>
>         The easiest way to do this (and it's not so easy) is to set up
>         LVM to scan your other LVM devices using a second lvm.conf.
>          Essentially you configure both copies of LVM (the internal
>         one and the external one) in separate files with careful
>         limits on which devices may be scanned for PVs.
>
>         A generally better solution is just to use LVM on the outside
>         and pass through the LVs to look like local disks.  The
>         downside is that it requires cooperation from the Dom0 to
>         resize and snapshot; and that FS extensions currently require
>         rebooting the VM to pick up the size changes.  The upside is
>         the LVM is really simple to manage if you just do it outside,
>         and the volume is available to the Dom0 for mounting like you
>         described.
>
>         Unless you absolutely need snapshotting normally inside or
>         live resizing, I wouldn't go through the trouble of running
>         LVM inside of LVM.  It is fraught with peril.
>
>         I am aware that you are going to have to reinstall your
>         systems, but, if they are doing anything important, you should
>         avoid things that can fatally confuse LVM (like nested LVM
>         setups).  While you're at it, don't partition the disks inside
>         of the DomUs either.  Just pass through the partitions directly.
>
>         Good luck.
>
>         On Mar 30, 2008, at 4:34 PM, Simone wrote:
>>         I guess I am trying to do something unusual :)
>>
>>         Any thoughts?
>>
>>         Simone
>>
>>
>>         On Fri, Mar 28, 2008 at 6:47 PM, Simone <dezmodue@xxxxxxxxx
>>         <mailto:dezmodue@xxxxxxxxx>> wrote:
>>
>>             Hi list,
>>
>>             I am experiencing with xen on centos5 and so far
>>             everything is going well, I am really pleased. The domU
>>             have a dedicated LV (/dev/vg1/xenVM1, /dev/vg1/xenVM2
>>             etc) and the guest OS is Centos4. At guest install time I
>>             have choosen to use LVM so that also inside the guest I
>>             have /dev/vg0/root, /dev/vg0/tmp etc. Is there a way to
>>             mount and edit the guest filesystem to customize files etc?
>>             The idea would be to have a guest template that can be
>>             cloned and then edited to generate new VMs.
>>
>>             Thanks, have a good weekend
>>
>>             Simone
>>
>>
>>
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>
>
>
>         -- 
>         Jayson Vantuyl
>         Systems Architect
>         *Engine Yard <http://www.engineyard.com>*
>         jvantuyl@xxxxxxxxxxxxxx <mailto:jvantuyl@xxxxxxxxxxxxxx>
>         1 866 518 9275 ext 204
>
>
>
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Tips, for your case  : http://www.novell.com/coolsolutions/tip/19568.html.

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