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RE: [Xen-users] Limited number of phy disks?


  • To: "'Xen Users Mailing List'" <xen-users@xxxxxxxxxxxxxxxxxxx>
  • From: "Dustin Henning" <Dustin.Henning@xxxxxxxxxxx>
  • Date: Mon, 19 Jan 2009 12:34:15 -0500
  • Delivery-date: Mon, 19 Jan 2009 09:35:03 -0800
  • List-id: Xen user discussion <xen-users.lists.xensource.com>
  • Thread-index: Acl6SbG+XLCXY/BBQdyf2Wiy5f5AewAEfYrg

       OK, that post puts me in the minority, and I havenât searched or tested 
to verify this, but I thought the only problem with SCSI emulation in Xen on 
HVMs was that the QEMU BIOS wouldnât boot to a SCSI drive.  My understanding is 
that the drives will be emulated, but you would need drivers for them in order 
to use them.  I would also go as far as to swear up and down that I have seen 
SCSI drivers for Xen HVMs more than once (once they werenât for HDs, but I 
think they were the other time).  Regardless, emulating SCSI shouldn't provide 
any performance increase once using PV drivers anyway.
        Dustin

From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Nick Couchman
Sent: Monday, January 19, 2009 10:02
To: pasik@xxxxxx
Cc: christoffer@xxxxxxxxx; xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Limited number of phy disks?

As far as I know, the current Qemu implementation in Xen for HVM support does 
not support SCSI.  As James pointed out, though, if you use the GPL PV drivers, 
you can assign as many devices as you want to the HVM domU.  The catch to that 
is that if you ever have to boot with /nogplpv (to disable the GPL PV drivers), 
you'll lose everything except disk devices hda-hdd.

-Nick


-----Original Message-----
From: Pasi KÃrkkÃinen <pasik@xxxxxx>
To: Nick Couchman <Nick.Couchman@xxxxxxxxx>
Cc: christoffer@xxxxxxxxx, xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Limited number of phy disks?
Date: Mon, 19 Jan 2009 16:03:43 +0200

On Sun, Jan 18, 2009 at 02:45:06PM -0700, Nick Couchman wrote:
> I assume you're running as an HVM?  What version of Xen are you using?  
> As far as I know, Xen only support IDE drives in HVM domUs, 
> and it only supports a total of four drives - hda, hdb, hdc, and hdd.
> 

Hi.

Afaik Qemu supports SCSI disk/adapter emulation nowadays too.. 
SCSI disk support is not yet implemented in Xen (version of Qemu)? 

-- Pasi
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