Pkg xen devel - Dec 2012 - Bug#695645: xen-utils-common: xm block-attach does not create /dev/xvd* devices on dom0

Package: xen-utils-common
Version: 4.1.3-6
Severity: minor

Dear Maintainer,

I am trying to run the following command on a dom0 Debian server in order to
mount a vmware vmdk.  I don't want to use kpartx or losetup as they have
poor write performance and I'm hoping blktap will provide better
performance.

xm block-attach 0 tap:vmdk:/mnt/backup/3MSYDDP01/3MSYDDP01_2-flat.vmdk
/dev/xvda1 w 0

However /dev/xvda1 is not created.  I have loaded to following modules for good
measure:

modprobe blktap
modprobe xen-blkback
modprobe xen-blkfront
modprobe xen-evtchn
modprobe xenfs
modprobe xen-gntalloc
modprobe xen-gntdev
modprobe xen-netback
modprobe xen-netfront
modprobe xen-pciback
modprobe xen-pcifront
modprobe xen_wdt

And tried manually creating the blokc device beforehand.

mknod /dev/xvda1 b 220 0

I searched for answers and found nothing that suggests that shouldn't work?

-- System Information:
Debian Release: wheezy/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 3.2.0-4-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages xen-utils-common depends on:
ii  gawk            1:4.0.1+dfsg-2
ii  lsb-base        4.1+Debian8
ii  python          2.7.3~rc2-1
ii  ucf             3.0025+nmu3
ii  udev            175-7
ii  xenstore-utils  4.1.3-6

xen-utils-common recommends no packages.

xen-utils-common suggests no packages.

-- debconf-show failed

On Tue, 2012-12-11 at 15:05 +1100, James Robertson
wrote:
> Package: xen-utils-common
> Version: 4.1.3-6
> Severity: minor
> 
> Dear Maintainer,
> 
> I am trying to run the following command on a dom0 Debian server in
> order to mount a vmware vmdk.  I don't want to use kpartx or losetup
> as they have poor write performance and I'm hoping blktap will provide
> better performance.
> 
> xm block-attach 0
> tap:vmdk:/mnt/backup/3MSYDDP01/3MSYDDP01_2-flat.vmdk /dev/xvda1 w 0
> 
> However /dev/xvda1 is not created.
There is no blktap driver in the main line kernels. You could try the
blktap dkms package which is in Wheezy.

Since that it blktap2 you probably want to setup the tap device using
tap-ctl directly rather than creating an xvd device in dom0, doing it
via xm likely won't work anyway.

I don't know the specifics of how to do this though -- perhaps google or
the upstream xen-users@ list can help.

There are also various offline conversion tools which you could
consider.

Ian.
-- 
Ian Campbell
Current Noise: Suffocation - Entrails Of You

A classic is something that everyone wants to have read
and nobody wants to read.
		-- Mark Twain, "The Disappearance of Literature"

Thanks, I have reviewed tap-ctl and it should provide what I need.

Bug report can be closed.

Thanks again.
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