Failed to create VM using configuration specified by Remus

Failed to create VM using configuration specified by Remus

[Minjia Zhang]

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I fail to use remus with xen-unstable (4.1)+ Linux-2.6.18.8:

[root@server1 img]# xm create rhel5.hvm
Using config file "./rhel5.hvm".
Error: Device 768 (tap) could not be connected.
server1:9000|aio:/dev/vgxen/hvmsnap does not exist

Am I missing something? Any hints will be appreciated.

According to Brendan's instruction on http://dsg.cs.ubc.ca/remus/doc.html
the config should like following:
disk = [ 'tap:remus:bkup:9000|aio:/dev/vmdisk/myguest,xvda1,w' ]

According to my understanding，remus doesn't need the support of DRBD, cause
it can continuously send memory state to backup server as well as write
operation and network
packages. So, what I do is to only ensure that /dev/vgxen/hvmsnap existing
on both the primary and the backup and contain identical data.

My config file:
  1 import os, re
  2 arch = os.uname()[4]
  3 if re.search('64', arch):
  4     arch_libdir = 'lib64'
  5 else:
  6     arch_libdir = 'lib'
  7 kernel = '/usr/lib/xen/boot/hvmloader'
  8 builder = 'hvm'
  9 memory = '512'
 14 disk = [ 'tap:remus:server1:9000|aio:/dev/vgxen/hvmsnap,hda,w']
 16 vif = ['type=ioemu, mac=00:1c:3e:17:22:13']
 17 #boot = 'dc'
 18 boot = 'c'
 19 name = 'Rhel5-hvm1'
 20 acpi = 1
 21 apic = 1
 22 device_model = '/usr/' + arch_libdir + '/xen/bin/qemu-dm'
 23 vnc=1
 24 vncdisplay=2
 25 sdl=0
 26 opengl=1
 27 vnclisten="0.0.0.0"
 28 vncpasswd=''
 29 serial='pty'
"hvm.hvm" 29L, 975C



Thanks for any help.

Best

--Minjia

-- 
-- 
Best Regards

Minjia Zhang

Huazhong University of Science and Technology

Room 328,Dong 8 Building 8, No.1037 Luoyu Road, Wuhan 430074, P.R.C.

Tel: +86-159-2625-3437

Email:zhangninja@gmail.com <Email%3Azhangninja@gmail.com>

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Re: Failed to create VM using configuration specified by Remus

[Brendan Cully]

On Friday, 02 April 2010 at 22:29, Minjia Zhang wrote:
> I fail to use remus with xen-unstable (4.1)+ Linux-2.6.18.8:
> 
> [root@server1 img]# xm create rhel5.hvm
> Using config file "./rhel5.hvm".
> Error: Device 768 (tap) could not be connected.
> server1:9000|aio:/dev/vgxen/hvmsnap does not exist
> 
> Am I missing something? Any hints will be appreciated.
> 
> According to Brendan's instruction on http://dsg.cs.ubc.ca/remus/doc.html
> the config should like following:
> disk = [ 'tap:remus:bkup:9000|aio:/dev/vmdisk/myguest,xvda1,w' ]
> 
> According to my understanding，remus doesn't need the support of DRBD, cause
> it can continuously send memory state to backup server as well as write
> operation and network
> packages. So, what I do is to only ensure that /dev/vgxen/hvmsnap existing
> on both the primary and the backup and contain identical data.

That's correct.

> My config file:
>   1 import os, re
>   2 arch = os.uname()[4]
>   3 if re.search('64', arch):
>   4     arch_libdir = 'lib64'
>   5 else:
>   6     arch_libdir = 'lib'
>   7 kernel = '/usr/lib/xen/boot/hvmloader'
>   8 builder = 'hvm'
>   9 memory = '512'
>  14 disk = [ 'tap:remus:server1:9000|aio:/dev/vgxen/hvmsnap,hda,w']
>  16 vif = ['type=ioemu, mac=00:1c:3e:17:22:13']
>  17 #boot = 'dc'
>  18 boot = 'c'
>  19 name = 'Rhel5-hvm1'
>  20 acpi = 1
>  21 apic = 1
>  22 device_model = '/usr/' + arch_libdir + '/xen/bin/qemu-dm'
>  23 vnc=1
>  24 vncdisplay=2
>  25 sdl=0
>  26 opengl=1
>  27 vnclisten="0.0.0.0"
>  28 vncpasswd=''
>  29 serial='pty'
> "hvm.hvm" 29L, 975C

This config looks ok to me. You'll get an error like that with pygrub,
which doesn't work with the Remus disk replication yet, but your HVM
config looks correct. I've just tested 32-bit HVM ubuntu on
xen-4.0-testing (rc9), and this syntax works here.

I don't suppose you have any more information in /var/log/daemon.log
or the xen logs (e.g., /var/log/xen/xend.log) ?

Re: Failed to create VM using configuration specified by Remus

[Minjia Zhang]

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Hi, Brendan,
Thank you very much for your reply and help. I've tested Remus with
xen-unstable-4.0 and the latest linux-2.6.18-xen.hg.  The remus seems to
work well. The previous error seems caused by using an old version of
linux-2.6.18-xen.hg and I've fixed it.

I encounter some problem when try to run remus with two vms on one
single physical  machine,like:
remus vm1 backup
remus vm2 backup
The first command can run correctly, while the second line get error and
give the following messages. Can Remus provide two vms (on one physical
machine) the fault tolerance simultaneously?

[root@server1 test]# remus 34 server2

ERROR Internal error: Can't create lock file for suspend event channel

WARNING: suspend event channel unavailable, falling back to slow xenstore
signalling

Had 0 unexplained entries in p2m table

 1: sent 64491, skipped 725, delta 3425ms, dom0 75%, target 75%, sent
617Mb/s, dirtied 10Mb/s 1085 pages

 2: sent 1083, skipped 2, delta 43ms, dom0 100%, target 100%, sent 825Mb/s,
dirtied 12Mb/s 16 pages

 3: sent 15, skipped 1, Start last iteration

PROF: suspending at 1271404630.401318

installing buffer on imq0

RTNETLINK answers: File exists

ERROR Internal error: Suspend request failed

ERROR Internal error: Domain appears not to have suspended

Save exit rc=1

Traceback (most recent call last):

  File "/usr/bin/remus", line 359, in ?

    run(cfg)

  File "/usr/bin/remus", line 340, in run

    for buf in bufs:

  File "/usr/bin/remus", line 277, in postsuspend

    buf.postsuspend()

  File "/usr/bin/remus", line 159, in postsuspend

    self._setup()

  File "/usr/bin/remus", line 185, in _setup

    self.rth.talk(req.pack())

  File "usr/lib/python2.4/site-packages/xen/remus/netlink.py", line 314, in
talk

IOError: error sending message


On Tue, Apr 6, 2010 at 5:30 AM, Brendan Cully <brendan@cs.ubc.ca> wrote:

> On Friday, 02 April 2010 at 22:29, Minjia Zhang wrote:
> > I fail to use remus with xen-unstable (4.1)+ Linux-2.6.18.8:
> >
> > [root@server1 img]# xm create rhel5.hvm
> > Using config file "./rhel5.hvm".
> > Error: Device 768 (tap) could not be connected.
> > server1:9000|aio:/dev/vgxen/hvmsnap does not exist
> >
> > Am I missing something? Any hints will be appreciated.
> >
> > According to Brendan's instruction on
> http://dsg.cs.ubc.ca/remus/doc.html
> > the config should like following:
> > disk = [ 'tap:remus:bkup:9000|aio:/dev/vmdisk/myguest,xvda1,w' ]
> >
> > According to my understanding，remus doesn't need the support of DRBD,
> cause
> > it can continuously send memory state to backup server as well as write
> > operation and network
> > packages. So, what I do is to only ensure that /dev/vgxen/hvmsnap
> existing
> > on both the primary and the backup and contain identical data.
>
> That's correct.
>
> > My config file:
> >   1 import os, re
> >   2 arch = os.uname()[4]
> >   3 if re.search('64', arch):
> >   4     arch_libdir = 'lib64'
> >   5 else:
> >   6     arch_libdir = 'lib'
> >   7 kernel = '/usr/lib/xen/boot/hvmloader'
> >   8 builder = 'hvm'
> >   9 memory = '512'
> >  14 disk = [ 'tap:remus:server1:9000|aio:/dev/vgxen/hvmsnap,hda,w']
> >  16 vif = ['type=ioemu, mac=00:1c:3e:17:22:13']
> >  17 #boot = 'dc'
> >  18 boot = 'c'
> >  19 name = 'Rhel5-hvm1'
> >  20 acpi = 1
> >  21 apic = 1
> >  22 device_model = '/usr/' + arch_libdir + '/xen/bin/qemu-dm'
> >  23 vnc=1
> >  24 vncdisplay=2
> >  25 sdl=0
> >  26 opengl=1
> >  27 vnclisten="0.0.0.0"
> >  28 vncpasswd=''
> >  29 serial='pty'
> > "hvm.hvm" 29L, 975C
>
> This config looks ok to me. You'll get an error like that with pygrub,
> which doesn't work with the Remus disk replication yet, but your HVM
> config looks correct. I've just tested 32-bit HVM ubuntu on
> xen-4.0-testing (rc9), and this syntax works here.
>
> I don't suppose you have any more information in /var/log/daemon.log
> or the xen logs (e.g., /var/log/xen/xend.log) ?
>



-- 
-- 
Best Regards

Minjia Zhang

Huazhong University of Science and Technology

Room 328,Dong 8 Building 8, No.1037 Luoyu Road, Wuhan 430074, P.R.C.

Tel: +86-159-2625-3437

Email:zhangninja@gmail.com <Email%3Azhangninja@gmail.com>

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Re: Re: Failed to create VM using configuration specified by Remus

[Brendan Cully]

On Friday, 16 April 2010 at 17:09, Minjia Zhang wrote:
> Hi, Brendan,
> Thank you very much for your reply and help. I've tested Remus with
> xen-unstable-4.0 and the latest linux-2.6.18-xen.hg.  The remus seems to
> work well. The previous error seems caused by using an old version of
> linux-2.6.18-xen.hg and I've fixed it.
> 
> I encounter some problem when try to run remus with two vms on one
> single physical  machine,like:
> remus vm1 backup
> remus vm2 backup
> The first command can run correctly, while the second line get error and
> give the following messages. Can Remus provide two vms (on one physical
> machine) the fault tolerance simultaneously?

It should -- I believe I even tried it out once or twice. The errors
below look like they're all pretty trivial to fix.

> [root@server1 test]# remus 34 server2
> 
> ERROR Internal error: Can't create lock file for suspend event channel

I think this is a lock file added to xm migrate? From the sound of it,
it's a global lock rather than per-domain, which would be
unnecessarily conservative. Probably easy to fix.

> WARNING: suspend event channel unavailable, falling back to slow xenstore
> signalling
> 
> Had 0 unexplained entries in p2m table
> 
>  1: sent 64491, skipped 725, delta 3425ms, dom0 75%, target 75%, sent
> 617Mb/s, dirtied 10Mb/s 1085 pages
> 
>  2: sent 1083, skipped 2, delta 43ms, dom0 100%, target 100%, sent 825Mb/s,
> dirtied 12Mb/s 16 pages
> 
>  3: sent 15, skipped 1, Start last iteration
> 
> PROF: suspending at 1271404630.401318
> 
> installing buffer on imq0
> 
> RTNETLINK answers: File exists

Yes, this is also quite a straightforward bug. The remus script
hardcodes imq0 instead of looking for the next available
device. Should be pretty easy to fix -- want to give it a shot?