Re: Xen partition saving (was: [Xen-users] xm save issue)

[John McCullough <jmccullo@xxxxxxxxxxx>]

Gordon,
  
    It is my understanding that when you define a disk, the booted OS
treats it as an actual disk device, rather than just a partition.
Consequentially, it's contents will reflect that of a full hard disk: a
partition table and boot record at the start, followed by the actual
partitions.
    I would wager that fdisk /dev/sdb5 would show you the partition
table that your Windows XP instance is using.  If you wanted to make a
copy of the entire disk you could probably use dd, but there are other
solutions.
    Snapshots allow you to keep a checkpoint of your filesystem and
could allow you to come back to an old version later.  One solution is
LVM.  See http://tldp.org/HOWTO/LVM-HOWTO/index.html for more
information on that.  Xen is going to start using QCOW (Qemu's copy on
write disk images) for the backend.  I am not familiar with it, but I
believe it will provide similar snapshotting functionality. 

~John
 
On Wed, Jul 12, 2006 at 01:27:08PM -0700, McFadden, Gordon wrote:
> 
> John,
> 
> Thanks for the information.
> 
> What I am trying do is create a copy of a virtual machine that can be
> restored.   The virtual machine is a Windows XP instance.
> 
> I am now looking at trying to take an image (or copy) of the partition I
> used.  In the hvm ocnfig file, I use a reference like:
> 
> disk = [ 'phy:/dev/sdb5,ioemu:hda,w' ]
> 
> In fdisk, sdb looks like:
> 
> [root@cso-gm-desk xen]# fdisk /dev/sdb
> 
> The number of cylinders for this disk is set to 30401.
> There is nothing wrong with that, but this is larger than 1024,
> and could in certain setups cause problems with:
> 1) software that runs at boot time (e.g., old versions of LILO)
> 2) booting and partitioning software from other OSs
>    (e.g., DOS FDISK, OS/2 FDISK)
> 
> Command (m for help): p
> 
> Disk /dev/sdb: 250.0 GB, 250059350016 bytes
> 255 heads, 63 sectors/track, 30401 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> 
>    Device Boot      Start         End      Blocks   Id  System
> ...
> /dev/sdb5            5377        7926    20482843+  83  Linux
> 
> But when I try to use some traditional partition tools, I get an error
> about an unknown file type (not ext3fs, or ext2fs, or ntfs, etc).
> 
> I am looking for a solution.  One thing I was thinking was changing the
> id (83) to NTFS (7).  Anyone think this would work?
> 
> Any other thoughts on how to do this task?
> 
> 
> Thx
> 
> Gord
> 
> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of John
> McCullough
> Sent: Wednesday, July 12, 2006 11:43 AM
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] xm save issue
> 
> Gordon,
> 
> Save is not implemented for hvm guests yet.  According to the roadmap it
> should be done within a few months.
> 
> Regards,
> John McCullough
> 
> On Wed, Jul 12, 2006 at 11:07:50AM -0700, McFadden, Gordon wrote:
> >  
> > 
> > Looking through the archives I see a few people had a similar problem
> I
> > am facing, but I do not see any solutions.
> > 
> >  
> > 
> > I am trying to execute a xm save and am getting the familiar 
> > 
> >  
> > 
> > XendError: /usr/lib64/xen/bin/xc_save 11 18 9 0 0 0 failed 
> > 
> > error message.
> > 
> >  
> > 
> > The xend.log contains:
> > 
> >  
> > 
> > [2006-07-12 11:03:51 xend] DEBUG (XendCheckpoint:80) [xc_save]:
> > /usr/lib64/xen/bin/xc_save 11 18 9 0 0 0
> > 
> > [2006-07-12 11:03:51 xend] ERROR (XendCheckpoint:227) Couldn't map
> > p2m_frame_list_list (errno 14): 14
> > 
> > [2006-07-12 11:03:51 xend] ERROR (XendCheckpoint:227) Save exit rc=1
> > 
> > [2006-07-12 11:03:51 xend] ERROR (XendCheckpoint:99) Save failed on
> > domain win_xp (9).
> > 
> > Traceback (most recent call last):
> > 
> >   File "/usr/lib64/python/xen/xend/XendCheckpoint.py", line 93, in
> save
> > 
> >     forkHelper(cmd, fd, saveInputHandler, False)
> > 
> >   File "/usr/lib64/python/xen/xend/XendCheckpoint.py", line 218, in
> > forkHelper
> > 
> >     raise XendError("%s failed" % string.join(cmd))
> > 
> > XendError: /usr/lib64/xen/bin/xc_save 11 18 9 0 0 0 failed
> > 
> >  
> > 
> >  
> > 
> > Any clues to this?
> > 
> >  
> > 
> > Thanks
> > 
> >  
> > 
> > Gord
> > 
> 
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-users
> 
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