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Trevor Bentley

2008-Sep-18 19:55 UTC

[Xen-users] Migration stalls with 2.6.26.5 kernel

Hello,

I have been struggling through the task of moving our infrastructure 
over to Xen VMs.  We were initially using Ubuntu packages for both dom0 
and our domUs, but experienced extreme instability so we moved to 
CentOS, which has been much more reliable for dom0.   Since we already 
had a bunch of Ubuntu VMs, we left them using the Ubuntu 2.4.24-19-xen 
kernel, but this has turned out to be a mistake -- we get frequent 
kernel oopses during heavy disk I/O.  We modified the kernel to add 
NFS-root support, but that is the only change we made to the original 
config.  All of our domUs mount their root file systems over NFS.

My problem is that I tried to upgrade the domU kernels to the latest 
kernel.org stable release (2.6.26.5) and did manage to get it working 
after some initial trouble (TCP checksum offloading was breaking NFS).  
However, the new kernel will not live migrate anymore.  When I execute 
the live migrate command:

# xm migrate --live testvm 192.168.1.20

Migration hangs forever.  The VM changes name to "migrate-testvm" and 
keeps running normally on the system it was on, and appears as
"testvm"
with state "-br---" on the destination machine with 0 CPU time.  I
left
tcpdump running on the destination machine and captured an 84MB pcap 
file which looked pretty normal up until all traffic just completely 
stopped.  If I just change the "kernel=" line in the config script to 
the Ubuntu kernel migration works again.

Here''s my VM configuration:
-------------------                                  
name        = ''testvm''
kernel      = ''/xen_vm/global/kernels/vmlinuz-2.6.26.5''
ramdisk     = ''/xen_vm/global/kernels/initrd.img-xen-latest''
memory      = ''256''
disk        =
[''tap:aio:/xen_vm/global/swaps/testvm.img,xvda1,w'']
vif         = [
                ''mac=00:16:3e:5b:8d:5d,bridge=xenbr0'',
                ''mac=00:16:3e:99:9b:e7,bridge=xenbr1''
              ]
on_poweroff = ''destroy''
on_reboot   = ''restart''
on_crash    = ''restart''
extra       = ''2 console=hvc0 root=/dev/nfs
ip=:192.168.1.12::::eth1:''
nfs_server  = ''192.168.1.12''
nfs_root    = ''/xen_vm/testvm''
-------------------


xend.log on source:
-------------------
[2008-09-18 15:51:11 xend 3751] DEBUG (balloon:127) Balloon: 786956 KiB 
free; need 2048; done.
[2008-09-18 15:51:11 xend 3751] DEBUG (XendCheckpoint:89) [xc_save]: 
/usr/lib/xen/bin/xc_save 33 38 0 0 1
-------------------

xend.log on destination:
-------------------
...
[2008-09-18 15:51:11 xend.XendDomainInfo 3331] DEBUG 
(XendDomainInfo:1350) XendDomainInfo.construct: None
[2008-09-18 15:51:11 xend 3331] DEBUG (balloon:127) Balloon: 262832 KiB 
free; need 2048; done.
...
[2008-09-18 15:51:11 xend 3331] DEBUG (blkif:24) exception looking up 
device number for xvda1: [Errno 2] No such file or directory:
''/dev/xvda1''
[2008-09-18 15:51:11 xend 3331] DEBUG (DevController:110) DevController: 
writing {''backend-id'': ''0'',
''virtual-device'': ''51713'',
''device-type'':
''disk'', ''state'': ''1'',
''backend'':
''/local/domain/0/backend/tap/10/51713''}
to /local/domain/10/device/vbd/51713.
...
[2008-09-18 15:51:12 xend 3331] DEBUG (XendCheckpoint:198) 
restore:shadow=0x0, _static_max=0x100, _static_min=0x100,
[2008-09-18 15:51:12 xend 3331] DEBUG (balloon:127) Balloon: 262832 KiB 
free; need 262144; done.
[2008-09-18 15:51:12 xend 3331] DEBUG (XendCheckpoint:215) [xc_restore]: 
/usr/lib/xen/bin/xc_restore 24 10 1 2 0 0 0
-------------------


Xen version: xen-3.0-x86_32p
dom0: 2.6.18-92.1.10.el5xen

Anybody know what would cause this, or have any suggestions for tracking 
down the problem?  I did find a post from someone who was seeing 
identical behavior who claimed he fixed it by enabling CPU Hotplug 
support, but I already have that enabled in the kernel.

Thanks,

Trevor

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Nemeth, Tamas

2008-Sep-18 20:13 UTC

head link

Re: [Xen-users] Migration stalls with 2.6.26.5 kernel

Hi!

Migrating, save, restore, etc. are scheduled for 2.6.27. Balloning is
also broken in early 2.6.26. I don''t know if it is still broken. Even
using more than one vcpu makes most domU kernels unrelianbe. The only
reliable and fully-supported kernels seem to be the original xen.org
kernels (2.8.18.8) both as dom0 and domU. I''ve had a lot of struggle
related to tis topic.

Cheers:

Tamas

PS:

Take a look at the archives of the xen-devel mailing list at
around Tue, 22 Jul 2008 18:11:26 -0600! 	Thread: [Xen-devel] PROBLEM:
Xen ballon driver seems to be broken 


2008. 09. 18, csütörtök keltezéssel 15.55-kor Trevor Bentley ezt
írta:> Hello,
> 
> I have been struggling through the task of moving our infrastructure 
> over to Xen VMs.  We were initially using Ubuntu packages for both dom0 
> and our domUs, but experienced extreme instability so we moved to 
> CentOS, which has been much more reliable for dom0.   Since we already 
> had a bunch of Ubuntu VMs, we left them using the Ubuntu 2.4.24-19-xen 
> kernel, but this has turned out to be a mistake -- we get frequent 
> kernel oopses during heavy disk I/O.  We modified the kernel to add 
> NFS-root support, but that is the only change we made to the original 
> config.  All of our domUs mount their root file systems over NFS.
> 
> My problem is that I tried to upgrade the domU kernels to the latest 
> kernel.org stable release (2.6.26.5) and did manage to get it working 
> after some initial trouble (TCP checksum offloading was breaking NFS).  
> However, the new kernel will not live migrate anymore.  When I execute 
> the live migrate command:
> 
> # xm migrate --live testvm 192.168.1.20
> 
> Migration hangs forever.  The VM changes name to "migrate-testvm"
and
> keeps running normally on the system it was on, and appears as
"testvm"
> with state "-br---" on the destination machine with 0 CPU time. 
I left
> tcpdump running on the destination machine and captured an 84MB pcap 
> file which looked pretty normal up until all traffic just completely 
> stopped.  If I just change the "kernel=" line in the config
script to
> the Ubuntu kernel migration works again.
> 
> Here''s my VM configuration:
> -------------------                                  
> name        = ''testvm''
> kernel      = ''/xen_vm/global/kernels/vmlinuz-2.6.26.5''
> ramdisk     =
''/xen_vm/global/kernels/initrd.img-xen-latest''
> memory      = ''256''
> disk        =
[''tap:aio:/xen_vm/global/swaps/testvm.img,xvda1,w'']
> vif         = [
>                 ''mac=00:16:3e:5b:8d:5d,bridge=xenbr0'',
>                 ''mac=00:16:3e:99:9b:e7,bridge=xenbr1''
>               ]
> on_poweroff = ''destroy''
> on_reboot   = ''restart''
> on_crash    = ''restart''
> extra       = ''2 console=hvc0 root=/dev/nfs
ip=:192.168.1.12::::eth1:''
> nfs_server  = ''192.168.1.12''
> nfs_root    = ''/xen_vm/testvm''
> -------------------
> 
> 
> xend.log on source:
> -------------------
> [2008-09-18 15:51:11 xend 3751] DEBUG (balloon:127) Balloon: 786956 KiB 
> free; need 2048; done.
> [2008-09-18 15:51:11 xend 3751] DEBUG (XendCheckpoint:89) [xc_save]: 
> /usr/lib/xen/bin/xc_save 33 38 0 0 1
> -------------------
> 
> xend.log on destination:
> -------------------
> ...
> [2008-09-18 15:51:11 xend.XendDomainInfo 3331] DEBUG 
> (XendDomainInfo:1350) XendDomainInfo.construct: None
> [2008-09-18 15:51:11 xend 3331] DEBUG (balloon:127) Balloon: 262832 KiB 
> free; need 2048; done.
> ...
> [2008-09-18 15:51:11 xend 3331] DEBUG (blkif:24) exception looking up 
> device number for xvda1: [Errno 2] No such file or directory:
''/dev/xvda1''
> [2008-09-18 15:51:11 xend 3331] DEBUG (DevController:110) DevController: 
> writing {''backend-id'': ''0'',
''virtual-device'': ''51713'',
''device-type'':
> ''disk'', ''state'': ''1'',
''backend'':
''/local/domain/0/backend/tap/10/51713''}
> to /local/domain/10/device/vbd/51713.
> ...
> [2008-09-18 15:51:12 xend 3331] DEBUG (XendCheckpoint:198) 
> restore:shadow=0x0, _static_max=0x100, _static_min=0x100,
> [2008-09-18 15:51:12 xend 3331] DEBUG (balloon:127) Balloon: 262832 KiB 
> free; need 262144; done.
> [2008-09-18 15:51:12 xend 3331] DEBUG (XendCheckpoint:215) [xc_restore]: 
> /usr/lib/xen/bin/xc_restore 24 10 1 2 0 0 0
> -------------------
> 
> 
> Xen version: xen-3.0-x86_32p
> dom0: 2.6.18-92.1.10.el5xen
> 
> Anybody know what would cause this, or have any suggestions for tracking 
> down the problem?  I did find a post from someone who was seeing 
> identical behavior who claimed he fixed it by enabling CPU Hotplug 
> support, but I already have that enabled in the kernel.
> 
> Thanks,
> 
> Trevor
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Thiago Camargo Martins Cordeiro

2008-Sep-18 20:19 UTC

head link

Re: [Xen-users] Migration stalls with 2.6.26.5 kernel

Trevor,

 Let me talk about my experience with distros that have supported Xen on
their trees.

 The most stable packaged Xen-3.2 is on Debian Lenny with kernel 2.6.18-xen
from Debian Etch. See http://wiki.debian.org/Xen - Installation on lenny.

 If your are "nutz", use Debian Lenny with Xen-3.3 and
Linux-2.6.18.8-xen-3.3 from xen.org compiled by you.

 I have tried Ubuntu Hardy with kernel 2.6.24-21-xen and it ins''t
stable at
all, I can''t use nosmp with it, some aacraid bugs. My dom0 are all
Ubuntu
Hardy with Xen-3.3 and Linux 2.6.18.8-xen from xen.org, but now I have a
problem with pythom-xml package. On Debian I do not see any bug or
instability.

 That''s my opinion!

ps.: Sorry about my english...   ;-)

Regards,
Thiago

2008/9/18 Trevor Bentley <trevor.bentley@sherpasolutions.net>
> Hello,
>
> I have been struggling through the task of moving our infrastructure over
> to Xen VMs.  We were initially using Ubuntu packages for both dom0 and our
> domUs, but experienced extreme instability so we moved to CentOS, which has
> been much more reliable for dom0.   Since we already had a bunch of Ubuntu
> VMs, we left them using the Ubuntu 2.4.24-19-xen kernel, but this has
turned
> out to be a mistake -- we get frequent kernel oopses during heavy disk I/O.
>  We modified the kernel to add NFS-root support, but that is the only
change
> we made to the original config.  All of our domUs mount their root file
> systems over NFS.
>
> My problem is that I tried to upgrade the domU kernels to the latest
> kernel.org stable release (2.6.26.5) and did manage to get it working
> after some initial trouble (TCP checksum offloading was breaking NFS).
>  However, the new kernel will not live migrate anymore.  When I execute the
> live migrate command:
>
> # xm migrate --live testvm 192.168.1.20
>
> Migration hangs forever.  The VM changes name to "migrate-testvm"
and keeps
> running normally on the system it was on, and appears as "testvm"
with state
> "-br---" on the destination machine with 0 CPU time.  I left
tcpdump running
> on the destination machine and captured an 84MB pcap file which looked
> pretty normal up until all traffic just completely stopped.  If I just
> change the "kernel=" line in the config script to the Ubuntu
kernel
> migration works again.
>
> Here''s my VM configuration:
> -------------------                                  name        =
''testvm''
> kernel      = ''/xen_vm/global/kernels/vmlinuz-2.6.26.5''
> ramdisk     =
''/xen_vm/global/kernels/initrd.img-xen-latest''
> memory      = ''256''
> disk        =
[''tap:aio:/xen_vm/global/swaps/testvm.img,xvda1,w'']
> vif         = [
>               ''mac=00:16:3e:5b:8d:5d,bridge=xenbr0'',
>               ''mac=00:16:3e:99:9b:e7,bridge=xenbr1''
>             ]
> on_poweroff = ''destroy''
> on_reboot   = ''restart''
> on_crash    = ''restart''
> extra       = ''2 console=hvc0 root=/dev/nfs
ip=:192.168.1.12::::eth1:''
> nfs_server  = ''192.168.1.12''
> nfs_root    = ''/xen_vm/testvm''
> -------------------
>
>
> xend.log on source:
> -------------------
> [2008-09-18 15:51:11 xend 3751] DEBUG (balloon:127) Balloon: 786956 KiB
> free; need 2048; done.
> [2008-09-18 15:51:11 xend 3751] DEBUG (XendCheckpoint:89) [xc_save]:
> /usr/lib/xen/bin/xc_save 33 38 0 0 1
> -------------------
>
> xend.log on destination:
> -------------------
> ...
> [2008-09-18 15:51:11 xend.XendDomainInfo 3331] DEBUG (XendDomainInfo:1350)
> XendDomainInfo.construct: None
> [2008-09-18 15:51:11 xend 3331] DEBUG (balloon:127) Balloon: 262832 KiB
> free; need 2048; done.
> ...
> [2008-09-18 15:51:11 xend 3331] DEBUG (blkif:24) exception looking up
> device number for xvda1: [Errno 2] No such file or directory:
''/dev/xvda1''
> [2008-09-18 15:51:11 xend 3331] DEBUG (DevController:110) DevController:
> writing {''backend-id'': ''0'',
''virtual-device'': ''51713'',
''device-type'':
> ''disk'', ''state'': ''1'',
''backend'':
''/local/domain/0/backend/tap/10/51713''} to
> /local/domain/10/device/vbd/51713.
> ...
> [2008-09-18 15:51:12 xend 3331] DEBUG (XendCheckpoint:198)
> restore:shadow=0x0, _static_max=0x100, _static_min=0x100,
> [2008-09-18 15:51:12 xend 3331] DEBUG (balloon:127) Balloon: 262832 KiB
> free; need 262144; done.
> [2008-09-18 15:51:12 xend 3331] DEBUG (XendCheckpoint:215) [xc_restore]:
> /usr/lib/xen/bin/xc_restore 24 10 1 2 0 0 0
> -------------------
>
>
> Xen version: xen-3.0-x86_32p
> dom0: 2.6.18-92.1.10.el5xen
>
> Anybody know what would cause this, or have any suggestions for tracking
> down the problem?  I did find a post from someone who was seeing identical
> behavior who claimed he fixed it by enabling CPU Hotplug support, but I
> already have that enabled in the kernel.
>
> Thanks,
>
> Trevor
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Ferenc Wagner

2008-Sep-18 21:57 UTC

head link

Re: [Xen-users] Migration stalls with 2.6.26.5 kernel

"Nemeth, Tamas" <nice@titanic.nyme.hu> writes:
> Migrating, save, restore, etc. are scheduled for 2.6.27.
Yes, but the Debian 2.6.26 kernels have the necessary patches
backported, so they migrate just fine.  I don''t know how Ubuntu
kernels relate to those of Debian, but would expect much similarity.
Or simply use the Debian kernel.
-- 
Regards,
Feri.

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Trevor Bentley

2008-Sep-19 13:48 UTC

head link

Re: [Xen-users] Migration stalls with 2.6.26.5 kernel

It''s very unfortunate that the Xen is so picky about it''s domU
kernels.
I wonder how hardware providers based on Xen (like Virtual Iron) deal 
with this.  It seems a shame if they have to give you specific kernels 
to use.

Thanks for the Debian tip, though.  I downloaded the binary 
linux-image-* and linux-module-* packages for Lenny, made an initrd with 
the modules, and that kernel boots and migrates.  The first time I 
migrated it, though, migration failed and the domU died with a bunch of 
"WARNING: g.e. still in use!" errors, so once again I''m not
confident
about the stability. 

This leaves me with:
Ubuntu kernel - NFS-root works, migration works, kernel unstable
CentOS kernel - NFS-root broken (ignores no_root_squash)
kernel.org - NFS-root works, migration broken, kernel stable
Debian - NFS-root works, migration works, kernel possibly unstable

It''s unfortunate that it is so much trouble to get this working.  Xen
is
supposed to be making server administration easier, not harder!  
Hopefully it''ll stabilize soon.

Thanks,

Trevor



Thiago Camargo Martins Cordeiro wrote:> Trevor,
>
>  Let me talk about my experience with distros that have supported Xen 
> on their trees.
>
>  The most stable packaged Xen-3.2 is on Debian Lenny with kernel 
> 2.6.18-xen from Debian Etch. See http://wiki.debian.org/Xen - 
> Installation on lenny.
>
>  If your are "nutz", use Debian Lenny with Xen-3.3 and 
> Linux-2.6.18.8-xen-3.3 from xen.org <http://xen.org> compiled by you.
>
>  I have tried Ubuntu Hardy with kernel 2.6.24-21-xen and it ins''t 
> stable at all, I can''t use nosmp with it, some aacraid bugs. My
dom0
> are all Ubuntu Hardy with Xen-3.3 and Linux 2.6.18.8-xen from xen.org 
> <http://xen.org>, but now I have a problem with pythom-xml package.
On
> Debian I do not see any bug or instability.
>
>  That''s my opinion!
>
> ps.: Sorry about my english...   ;-)
>
> Regards,
> Thiago
>
> 2008/9/18 Trevor Bentley <trevor.bentley@sherpasolutions.net 
> <mailto:trevor.bentley@sherpasolutions.net>>
>
>     Hello,
>
>     I have been struggling through the task of moving our
>     infrastructure over to Xen VMs.  We were initially using Ubuntu
>     packages for both dom0 and our domUs, but experienced extreme
>     instability so we moved to CentOS, which has been much more
>     reliable for dom0.   Since we already had a bunch of Ubuntu VMs,
>     we left them using the Ubuntu 2.4.24-19-xen kernel, but this has
>     turned out to be a mistake -- we get frequent kernel oopses during
>     heavy disk I/O.  We modified the kernel to add NFS-root support,
>     but that is the only change we made to the original config.  All
>     of our domUs mount their root file systems over NFS.
>
>     My problem is that I tried to upgrade the domU kernels to the
>     latest kernel.org <http://kernel.org> stable release (2.6.26.5
>     <http://2.6.26.5>) and did manage to get it working after some
>     initial trouble (TCP checksum offloading was breaking NFS).
>      However, the new kernel will not live migrate anymore.  When I
>     execute the live migrate command:
>
>     # xm migrate --live testvm 192.168.1.20 <http://192.168.1.20>
>
>     Migration hangs forever.  The VM changes name to
"migrate-testvm"
>     and keeps running normally on the system it was on, and appears as
>     "testvm" with state "-br---" on the destination
machine with 0 CPU
>     time.  I left tcpdump running on the destination machine and
>     captured an 84MB pcap file which looked pretty normal up until all
>     traffic just completely stopped.  If I just change the
"kernel="
>     line in the config script to the Ubuntu kernel migration works again.
>
>     Here''s my VM configuration:
>     -------------------                                  name        >  
''testvm''
>     kernel      =
''/xen_vm/global/kernels/vmlinuz-2.6.26.5''
>     ramdisk     =
''/xen_vm/global/kernels/initrd.img-xen-latest''
>     memory      = ''256''
>     disk        =
[''tap:aio:/xen_vm/global/swaps/testvm.img,xvda1,w'']
>     vif         = [
>                   ''mac=00:16:3e:5b:8d:5d,bridge=xenbr0'',
>                   ''mac=00:16:3e:99:9b:e7,bridge=xenbr1''
>                 ]
>     on_poweroff = ''destroy''
>     on_reboot   = ''restart''
>     on_crash    = ''restart''
>     extra       = ''2 console=hvc0 root=/dev/nfs
ip=:192.168.1.12::::eth1:''
>     nfs_server  = ''192.168.1.12
<http://192.168.1.12>''
>     nfs_root    = ''/xen_vm/testvm''
>     -------------------
>
>
>     xend.log on source:
>     -------------------
>     [2008-09-18 15:51:11 xend 3751] DEBUG (balloon:127) Balloon:
>     786956 KiB free; need 2048; done.
>     [2008-09-18 15:51:11 xend 3751] DEBUG (XendCheckpoint:89)
>     [xc_save]: /usr/lib/xen/bin/xc_save 33 38 0 0 1
>     -------------------
>
>     xend.log on destination:
>     -------------------
>     ...
>     [2008-09-18 15:51:11 xend.XendDomainInfo 3331] DEBUG
>     (XendDomainInfo:1350) XendDomainInfo.construct: None
>     [2008-09-18 15:51:11 xend 3331] DEBUG (balloon:127) Balloon:
>     262832 KiB free; need 2048; done.
>     ...
>     [2008-09-18 15:51:11 xend 3331] DEBUG (blkif:24) exception looking
>     up device number for xvda1: [Errno 2] No such file or directory:
>     ''/dev/xvda1''
>     [2008-09-18 15:51:11 xend 3331] DEBUG (DevController:110)
>     DevController: writing {''backend-id'':
''0'', ''virtual-device'':
>     ''51713'', ''device-type'':
''disk'', ''state'': ''1'',
''backend'':
>     ''/local/domain/0/backend/tap/10/51713''} to
>     /local/domain/10/device/vbd/51713.
>     ...
>     [2008-09-18 15:51:12 xend 3331] DEBUG (XendCheckpoint:198)
>     restore:shadow=0x0, _static_max=0x100, _static_min=0x100,
>     [2008-09-18 15:51:12 xend 3331] DEBUG (balloon:127) Balloon:
>     262832 KiB free; need 262144; done.
>     [2008-09-18 15:51:12 xend 3331] DEBUG (XendCheckpoint:215)
>     [xc_restore]: /usr/lib/xen/bin/xc_restore 24 10 1 2 0 0 0
>     -------------------
>
>
>     Xen version: xen-3.0-x86_32p
>     dom0: 2.6.18-92.1.10.el5xen
>
>     Anybody know what would cause this, or have any suggestions for
>     tracking down the problem?  I did find a post from someone who was
>     seeing identical behavior who claimed he fixed it by enabling CPU
>     Hotplug support, but I already have that enabled in the kernel.
>
>     Thanks,
>
>     Trevor
>
>     _______________________________________________
>     Xen-users mailing list
>     Xen-users@lists.xensource.com
<mailto:Xen-users@lists.xensource.com>
>     http://lists.xensource.com/xen-users
>
>
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