Xen users - Jun 2005 - About installing Virtual Machines in the same hdd partition

Hello everybody,
This is my first message in this mail list and it will not be the last one. 
The thing is that I''ve installed Xen without any problems on my Debian 
Sarge. I''ve rebooted the system and everything seems all right, i run
the
command uname -a, and I get that Xen kernel is running. 
The problem comes when I thing about installing a new Virtual Machine, I 
would not like to create a new partition in my hard disk to store the new 
virtual machine, what I would like to do is to have the same filesystems 
being shared by all the running Virtual Machines, plus Xen. Can I do this? 

Thank you.


_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Miguel Gómez wrote:
> The problem comes when I thing about installing a new Virtual Machine, 
> I would not like to create a new partition in my hard disk to store 
> the new virtual machine, what I would like to do is to have the same 
> filesystems being shared by all the running Virtual Machines, plus 
> Xen. Can I do this?
>
Short answer : No.

Long answer:
Linux requires some part of filesystem (/var, /tmp, etc.) to be 
available read-write.
Generally, you cannot (and should not) mount a partition (or any block 
device, or even loopback file system) read-write twice (or more) at the 
same time because it will cause inconsistency and data loss. You can, 
however, mount a block device read-only on multiple domains for some 
parts of file system (namely /usr). See 
http://www.cl.cam.ac.uk/Research/SRG/netos/xen/readmes/user/user.html#SECTION02330000000000000000

If you don''t want to create another partition, you can use file-backed 
VBDs, or use LVM (recommended).

Regards,

Fajar



_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Am Donnerstag 02 Juni 2005 10:42 schrieb Fajar A.
Nugraha:
> Miguel Gómez wrote:
> > The problem comes when I thing about installing a new Virtual Machine,
> > I would not like to create a new partition in my hard disk to store
> > the new virtual machine, what I would like to do is to have the same
> > filesystems being shared by all the running Virtual Machines, plus
> > Xen. Can I do this?
>
> Short answer : No.
>
> Long answer:
> Linux requires some part of filesystem (/var, /tmp, etc.) to be
> available read-write.
Hi,

can''t one circumvent this by mounting  ramdisks on these parts? Or if
the
whole root partition is not too big put it all in a ramdisk like on a 
diskless system?
One could also mount only one ramdisk and create links for tmp and var 
pointing to dirs on the ramdisk.

HTH

Claus


_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

On 02/06/05, Claus R. F. Overbeck <xen@clausrfoverbeck.de>
wrote:
> Am Donnerstag 02 Juni 2005 10:42 schrieb Fajar A. Nugraha:
> > Miguel Gómez wrote:
> > > The problem comes when I thing about installing a new Virtual
Machine,
> > > I would not like to create a new partition in my hard disk to
store
> > > the new virtual machine, what I would like to do is to have the
same
> > > filesystems being shared by all the running Virtual Machines,
plus
> > > Xen. Can I do this?
> >
> > Short answer : No.
> >
> > Long answer:
> > Linux requires some part of filesystem (/var, /tmp, etc.) to be
> > available read-write.
> 
> Hi,
> 
> can''t one circumvent this by mounting  ramdisks on these parts? Or
if the
> whole root partition is not too big put it all in a ramdisk like on a
> diskless system?
> One could also mount only one ramdisk and create links for tmp and var
> pointing to dirs on the ramdisk.
That would eat all your ram in the in the end.

-Marius

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Thank you for your help, I will try to create and mount LVM VBDs and see if 
it works fine. 

Regards, 

Miguel


_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users