RE: [Xen-users] Some Doubts regarding HVM

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: trilok nuwal [mailto:tc.nuwal@xxxxxxxxx] 
> Sent: 12 April 2007 13:12
> To: Petersson, Mats
> Cc: Xen list
> Subject: Re: [Xen-users] Some Doubts regarding HVM
> 
> 
> 
> On 4/12/07, Petersson, Mats <Mats.Petersson@xxxxxxx> wrote:
> 
> 
> 
>       > -----Original Message-----
>       > From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
>       > [mailto: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> <mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx> ] On Behalf Of
>       > trilok nuwal
>       > Sent: 12 April 2007 07:46
>       > To: Xen list
>       > Subject: [Xen-users] Some Doubts regarding HVM
>       >
>       > Hi All,
>       >
>       > My dom0  REHL5 xen OS.
>       >
>       > I installed RHEL4U4  on disk /dev/cciss/c0d1. I exported this
>       > to domU in config file as hda as below.
>       >
>       > disk = [ 'phy:/dev/cciss/c0d1,hda,w' , 
> 'phy:/dev/sdb2,hdb2,w' ] 
>       >
>       > hda is exported properly but my other partition /dev/sdb2 is
>       > not exported to Domu.
>       >
>       > And if I change to disk with full disk then it works fine.
>       >
>       > disk = [ 'phy:/dev/cciss/c0d1,hda,w' , 'phy:/dev/sdb,hdb,w' ] 
>       >
>       > So conclusion is that we can't export a partition in HVM
>       > case. Is it correct ?
>       
>       That is correct. The reason for this is that the 
> hardware emulation
>       layer doesn't know anything about partitions. You can 
> of course make a 
>       partition into a disk if you want, such as:
>       'phy:/dev/sdb2,hdb,w'
> 
> 
> I tried this phy:/dev/sdb2,hdb,w. So in DomU, i am able to 
> export and mount /dev/sdb2 partition. 
> So that mean, we can insatll an Linux OS on a partition and 
> can export this partition as disk and can mount in 
> guest OS as disk. It looks fine to me.

Yes, the HVM guest install will of course put it's own partition table
inside the partitiion (because the guest doesn't see that as a
partition, but as a DISK - it knows nothing of the difference). 
> 
> What u say. Should this work, i wll do some work on this and 
> let u know wht i get ?

Yes, I'm absolutely confident this works [you may need changes to the
exact way you specify the disk-line, but as a concept it should work
just fine].

Do let us know how you get along. 

--
Mats
> 
> 
> 
> 
>       But the hardware (or io) emulation doesn't have a clue 
> what a partition
>       is, because partitions are just a way for the OS to 
> partition a disk 
>       into sections (it used to be really important because 
> disks could only
>       have a certain size [x number of sectors, blocks or 
> clusters, whichever
>       the file-system utilized], but nowadays, with 64-bit pointers in
>       file-systems, it's pretty much just a organizational 
> tool to keep
>       different types of data separated from each other).
>       >
>       > If this then we cant install a OS on a partition and start a
>       > HVM domain. 
>       
>       That would be correct.
>       >
>       > My problem is that on my laptop i have a single hard disk, so
>       > i can't install a Guest OS on this, because this require a
>       > full disk to be exported to guest OS. 
>       
>       Get a USB-disk, perhaps?
>       
>       I don't believe Xen is meant to solve this problem, 
> really. [And I have
>       some doubt that you'd actually be successful in running 
> a native OS and
>       the same OS as guest-OS, but that's a different story]. 
>       
>       --
>       Mats
>       >
>       > Any help..
>       >
>       > Thanks,
>       > Trilok
>       >
>       >
>       
>       
>       
> 
> 
> 



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