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Re: [Xen-users] Driver/Backend Domains

To: Fasiha Ashraf <feehapk@xxxxxxxxxxx>
Subject: Re: [Xen-users] Driver/Backend Domains
From: Matthew Mallozzi <matt.mallozzi@xxxxxxxxxx>
Date: Fri, 03 Jul 2009 19:58:33 -0700
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No luck, but thanks for the tip - I did only have 8 before, and now I'm up to 256.

Is anyone familiar with the execution path of xm block-attach, so that I might be able to trace what's going on and where it's failing? I've followed it through the source until xm sends the request to xend, and that's where I lose it.

Fasiha Ashraf wrote:
"Error: Device 51744 (vbd) could not be connected. Hotplug
scripts not working.", which is quite vague."

You might have smaller no of loopback devices in your domain. By the default there are only 8 loops available. but you can increase the limit up to 256 max this way:-
1- Add this line to /etc/modprobe.conf
    options loop max_loop=256
2- The other way is to add 'loop' to /etc/modules
     and add the same above mentioned option in /etc/modprobe.d/options

Fasiha Ashraf

--- On *Fri, 3/7/09, Matthew Mallozzi /<matt.mallozzi@xxxxxxxxxx>/* wrote:

    From: Matthew Mallozzi <matt.mallozzi@xxxxxxxxxx>
    Subject: [Xen-users] Driver/Backend Domains
    To: xen-users@xxxxxxxxxxxxxxxxxxx
    Date: Friday, 3 July, 2009, 7:20 AM

    Forgot to mention - I also put the option "blkif=1" in the
    configuration file for the intended driver domain.
    What is required for a PV domU to act as a driver domain for a block
    device?  My goal is to attach a disk image file located within the
    to dom0 as a block device.  The command I am running in dom0 is
       xm block-attach 0 file:/root/hdisk.img /dev/xvdb w 2,
    where hdisk.img is the disk image file in domU, xvdb is the name
    of the
    intended device node in dom0, and 2 is the domain ID of the domU.

    My domU is a PV guest with its kernel replaced by the kernel from
    and I have copied over both /etc/xen/scripts and
    /usr/lib/python2.4/site-packages/xen from dom0 to the guest.  However,
    whenever I attempt the above command, it sits for a while and then
    returns with "Error: Device 51744 (vbd) could not be connected.
    scripts not working.", which is quite vague.

    Thank you!

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