xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

[Madjik]

Hi,

I'm currently trying xen 4.1.1 with the 3.0.0-rc5 (heard that it now 
contains the xen code to run as front or back xen domain).

Everything seems to run fine, except that I am trying since a  few hours 
to mount a .vhd file in the dom0.

What I tried so far:

to create a blank vhd file (this is working):
host# vhd-util create -n /storage/test.vhd -s 20G

Then i try to mount the file in dom0 (as stated in a blktap2 README file)
host# tapdisk2 -n vhc:/storage/test.vhd

it fails, returning:
tapdisk2: invalid option -- 'n'
usage: tapdisk2 <-u uuid> <-c control socket>

Then i've tried:
host# tap-ctl  list

It returns:
blktap kernel module not installed

Then tried too:
host# xl block-attach 0 tap:vhd:/storage/test.vhd xvda w 0

It does not complain but nothing happens.

Am I getting something wrong about how to do it ? Does the 3.0.0-rc5 
kernel is missing something ?
(look like there is no blktap module in the kernel tree, but blkback 
that I enabled, don't know if it's the same)

I have no more ideas about what to try next. Any clue ?

Thanks a lot for your help!

Kind regards,
Sébastien

Re: xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

[Ian Campbell]

On Wed, 2011-06-29 at 03:06 +0100, Madjik wrote:
> Hi,
> 
> I'm currently trying xen 4.1.1 with the 3.0.0-rc5 (heard that it now 
> contains the xen code to run as front or back xen domain).
> 
> Everything seems to run fine, except that I am trying since a  few hours 
> to mount a .vhd file in the dom0.

Everything needed to run a guest is upstream but not everything needed
to run any guest, if you see what I mean. In particular the upstream
kernel contains blkback but not blktap so using a vhd would not be
expected to work today.

I'm afraid blktap is unlikely to be accepted upstream as it is. There is
a plan to remove the kernel component and have guests communicate
directly with the tapdisk process in userspace (via /dev/xen/gtndev et
al). There is no real downside to this since everything goes through
tapdisk anyway. I don't know how advanced that plan is currently.

With the 4.1 release you might be able to use the qdisk (qemu based
backend) to run a VHD but it is known not to perform all that well (and
I don't know off-hand how you enable it). Performance is, AIUI, better
with the upstream qemu port.

Ian.

Re: xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

[Stefano Stabellini]

On Thu, 30 Jun 2011, Ian Campbell wrote:
> On Wed, 2011-06-29 at 03:06 +0100, Madjik wrote:
> > Hi,
> > 
> > I'm currently trying xen 4.1.1 with the 3.0.0-rc5 (heard that it now 
> > contains the xen code to run as front or back xen domain).
> > 
> > Everything seems to run fine, except that I am trying since a  few hours 
> > to mount a .vhd file in the dom0.
> 
> Everything needed to run a guest is upstream but not everything needed
> to run any guest, if you see what I mean. In particular the upstream
> kernel contains blkback but not blktap so using a vhd would not be
> expected to work today.
> 
> I'm afraid blktap is unlikely to be accepted upstream as it is. There is
> a plan to remove the kernel component and have guests communicate
> directly with the tapdisk process in userspace (via /dev/xen/gtndev et
> al). There is no real downside to this since everything goes through
> tapdisk anyway. I don't know how advanced that plan is currently.
> 
> With the 4.1 release you might be able to use the qdisk (qemu based
> backend) to run a VHD but it is known not to perform all that well (and
> I don't know off-hand how you enable it). Performance is, AIUI, better
> with the upstream qemu port.

If you want to run 3.0.0-rc5 as dom0 your best bet would be to convert
your vhd file to a raw file, setup LVM, then dd the raw file into a new
LVM volume. This in order to get the best performances.

Otherwise the easiest thing to do would be to clone a kernel tree that
contains blktap2, I believe Daniel has one based on 3.0, see the thread
"xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2".

Re: xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

[Ian Campbell]

On Thu, 2011-06-30 at 11:55 +0100, Stefano Stabellini wrote:
> On Thu, 30 Jun 2011, Ian Campbell wrote:
> > On Wed, 2011-06-29 at 03:06 +0100, Madjik wrote:
> > > Hi,
> > > 
> > > I'm currently trying xen 4.1.1 with the 3.0.0-rc5 (heard that it now 
> > > contains the xen code to run as front or back xen domain).
> > > 
> > > Everything seems to run fine, except that I am trying since a  few hours 
> > > to mount a .vhd file in the dom0.
> > 
> > Everything needed to run a guest is upstream but not everything needed
> > to run any guest, if you see what I mean. In particular the upstream
> > kernel contains blkback but not blktap so using a vhd would not be
> > expected to work today.
> > 
> > I'm afraid blktap is unlikely to be accepted upstream as it is. There is
> > a plan to remove the kernel component and have guests communicate
> > directly with the tapdisk process in userspace (via /dev/xen/gtndev et
> > al). There is no real downside to this since everything goes through
> > tapdisk anyway. I don't know how advanced that plan is currently.
> > 
> > With the 4.1 release you might be able to use the qdisk (qemu based
> > backend) to run a VHD but it is known not to perform all that well (and
> > I don't know off-hand how you enable it). Performance is, AIUI, better
> > with the upstream qemu port.
> 
> If you want to run 3.0.0-rc5 as dom0 your best bet would be to convert
> your vhd file to a raw file, setup LVM, then dd the raw file into a new
> LVM volume. This in order to get the best performances.
> 
> Otherwise the easiest thing to do would be to clone a kernel tree that
> contains blktap2, I believe Daniel has one based on 3.0, see the thread
> "xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2".

Um, that's this thread ;-)

Ian.

Re: xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

[Ian Campbell]

On Thu, 2011-06-30 at 12:00 +0100, Ian Campbell wrote:
> On Thu, 2011-06-30 at 11:55 +0100, Stefano Stabellini wrote:
> > On Thu, 30 Jun 2011, Ian Campbell wrote:

> > Otherwise the easiest thing to do would be to clone a kernel tree that
> > contains blktap2, I believe Daniel has one based on 3.0, see the thread
> > "xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2".
> 
> Um, that's this thread ;-)

Oh wait. the same person has started two threads, with the exact same
subject but from different email addresses.

Sebastian / Madjik -- please don't do that!

Ian.

Re: xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

[Sébastien Riccio]

Sorry, that was not intentional. Although I don't understand how I 
managed to
send the original mail from both mail accounts accounts :/


On 30.06.2011 13:02, Ian Campbell wrote:
> On Thu, 2011-06-30 at 12:00 +0100, Ian Campbell wrote:
>> On Thu, 2011-06-30 at 11:55 +0100, Stefano Stabellini wrote:
>>> On Thu, 30 Jun 2011, Ian Campbell wrote:
>>> Otherwise the easiest thing to do would be to clone a kernel tree that
>>> contains blktap2, I believe Daniel has one based on 3.0, see the thread
>>> "xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2".
>> Um, that's this thread ;-)
> Oh wait. the same person has started two threads, with the exact same
> subject but from different email addresses.
>
> Sebastian / Madjik -- please don't do that!
>
> Ian.
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>

xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

[Sébastien Riccio]

Hi,

I'm currently trying xen 4.1.1 with the 3.0.0-rc5 (heard that it now 
contains the xen code to run as front or back xen domain).

Everything seems to run fine, except that I am trying since a  few hours 
to mount a .vhd file in the dom0.

What I tried so far:

to create a blank vhd file (this is working):
host# vhd-util create -n /storage/test.vhd -s 20G

Then i try to mount the file in dom0 (as stated in a blktap2 README file)
host# tapdisk2 -n vhc:/storage/test.vhd

it fails, returning:
tapdisk2: invalid option -- 'n'
usage: tapdisk2 <-u uuid> <-c control socket>

Then i've tried:
host# tap-ctl  list

It returns:
blktap kernel module not installed

Then tried too:
host# xl block-attach 0 tap:vhd:/storage/test.vhd xvda w 0

It does not complain but nothing happens.

Am I getting something wrong about how to do it ? Does the 3.0.0-rc5 
kernel is missing something ?
(look like there is no blktap module in the kernel tree, but blkback 
that I enabled, don't know if it's the same)

I have no more ideas about what to try next. Any clue ?

Thanks a lot for your help!

Kind regards,
Sébastien

Re: xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

[Daniel Stodden]

On Tue, 2011-06-28 at 22:08 -0400, Sébastien Riccio wrote:
> Hi,
> 
> I'm currently trying xen 4.1.1 with the 3.0.0-rc5 (heard that it now 
> contains the xen code to run as front or back xen domain).
> 
> Everything seems to run fine, except that I am trying since a  few hours 
> to mount a .vhd file in the dom0.
> 
> What I tried so far:
> 
> to create a blank vhd file (this is working):
> host# vhd-util create -n /storage/test.vhd -s 20G
> 
> Then i try to mount the file in dom0 (as stated in a blktap2 README file)
> host# tapdisk2 -n vhc:/storage/test.vhd

tap-ctl create -n vhd:/storage/test.vhd # :)

As a rule of thumb, there's no excuse to call tapdisk2 on the command
line. Should actually rather have gone into libexec.

Daniel

> it fails, returning:
> tapdisk2: invalid option -- 'n'
> usage: tapdisk2 <-u uuid> <-c control socket>
> 
> Then i've tried:
> host# tap-ctl  list
> 
> It returns:
> blktap kernel module not installed
> 
> Then tried too:
> host# xl block-attach 0 tap:vhd:/storage/test.vhd xvda w 0
> 
> It does not complain but nothing happens.
> 
> Am I getting something wrong about how to do it ? Does the 3.0.0-rc5 
> kernel is missing something ?
> (look like there is no blktap module in the kernel tree, but blkback 
> that I enabled, don't know if it's the same)
> 
> I have no more ideas about what to try next. Any clue ?
> 
> Thanks a lot for your help!
> 
> Kind regards,
> Sébastien
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

Re: xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

[Daniel Stodden]

On Tue, 2011-06-28 at 22:32 -0400, Daniel Stodden wrote:
> On Tue, 2011-06-28 at 22:08 -0400, Sébastien Riccio wrote:
> > Hi,
> > 
> > I'm currently trying xen 4.1.1 with the 3.0.0-rc5 (heard that it now 
> > contains the xen code to run as front or back xen domain).
> > 
> > Everything seems to run fine, except that I am trying since a  few hours 
> > to mount a .vhd file in the dom0.
> > 
> > What I tried so far:
> > 
> > to create a blank vhd file (this is working):
> > host# vhd-util create -n /storage/test.vhd -s 20G
> > 
> > Then i try to mount the file in dom0 (as stated in a blktap2 README file)
> > host# tapdisk2 -n vhc:/storage/test.vhd
> 
> tap-ctl create -n vhd:/storage/test.vhd # :)
> 
> As a rule of thumb, there's no excuse to call tapdisk2 on the command
> line. Should actually rather have gone into libexec.
> 
> Daniel
> 
> > it fails, returning:
> > tapdisk2: invalid option -- 'n'
> > usage: tapdisk2 <-u uuid> <-c control socket>
> > 
> > Then i've tried:
> > host# tap-ctl  list
> > 
> > It returns:
> > blktap kernel module not installed

Yeah, we got blk*back* upstream, but not blktap.

You're building from git? Good.

$ git remote add daniel git://xenbits.xensource.com/people/dstodden/linux.git
$ git fetch daniel
$ git merge daniel/blktap/next-2.6.39

There might be a dedicated blktap/next-3.x at some point, but last time
I checked (which was -rc3), it should merge + build just fine.

$ make menuconfig
    drivers -> block -> "blktap userspace devices" -> m

$ ...
$ modprobe blktap

Daniel

> > Then tried too:
> > host# xl block-attach 0 tap:vhd:/storage/test.vhd xvda w 0
> > 
> > It does not complain but nothing happens.
> > 
> > Am I getting something wrong about how to do it ? Does the 3.0.0-rc5 
> > kernel is missing something ?
> > (look like there is no blktap module in the kernel tree, but blkback 
> > that I enabled, don't know if it's the same)
> > 
> > I have no more ideas about what to try next. Any clue ?
> > 
> > Thanks a lot for your help!
> > 
> > Kind regards,
> > Sébastien
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel
> 
> 

Re: xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

[Sébastien Riccio]

On 29.06.2011 04:32, Daniel Stodden wrote:
> On Tue, 2011-06-28 at 22:08 -0400, Sébastien Riccio wrote:
>> Hi,
>>
>> I'm currently trying xen 4.1.1 with the 3.0.0-rc5 (heard that it now
>> contains the xen code to run as front or back xen domain).
>>
>> Everything seems to run fine, except that I am trying since a  few hours
>> to mount a .vhd file in the dom0.
>>
>> What I tried so far:
>>
>> to create a blank vhd file (this is working):
>> host# vhd-util create -n /storage/test.vhd -s 20G
>>
>> Then i try to mount the file in dom0 (as stated in a blktap2 README file)
>> host# tapdisk2 -n vhc:/storage/test.vhd
> tap-ctl create -n vhd:/storage/test.vhd # :)
>
> As a rule of thumb, there's no excuse to call tapdisk2 on the command
> line. Should actually rather have gone into libexec.
>
> Daniel
>

Hi Daniel,

Thank you for your help. With this command I still get into the
"blktap kernel module not installed"

I'm using xen 4.1.1 compiled from source with a kernel 3.0.0-rc5 dom0 
(compiled with all xen stuff enabled).
Is there missing xen modules in the new kernel ? I try to use most 
recent xen enabled kernel. Is there a 2.3.29
xenfified kernel around ?

Thanks again,
Sébastien

Re: xen 4.1.1 + 3.0.0-rc5 dom0 + blktap2

[Sébastien Riccio]

On 29.06.2011 04:49, Daniel Stodden wrote:
> On Tue, 2011-06-28 at 22:41 -0400, Sébastien Riccio wrote:
>
>> Hi Daniel,
>>
>> Thank you for your help. With this command I still get into the
>> "blktap kernel module not installed"
>>
>> I'm using xen 4.1.1 compiled from source with a kernel 3.0.0-rc5 dom0
>> (compiled with all xen stuff enabled).
>> Is there missing xen modules in the new kernel ? I try to use most
>> recent xen enabled kernel. Is there a 2.3.29
>> xenfified kernel around ?
> Replies racing. See my related later mail. You'll need to merge a
> sufficiently recent blktap, I'd suggest to just pick it from here:
>
> http://xenbits.xensource.com/gitweb/?p=people/dstodden/linux.git;a=shortlog;h=refs/heads/blktap/next-2.6.39
>
> Daniel
>

Hehe, true, some reply racing occured here. I just read your precedent 
mail and it's now everything is crystal clear.

Thanks again for your help!

Best regards,
Sébastien