[Xen-users] domU migration from Xen 4.8 HyperVisor to Xen 4.4

Discussion:

Alessandro Tugnoli

2018-08-17 13:24:03 UTC

Hi all

I've just upgraded my hypervisor (let be "host1") to Debian 9 "Stretch"
with Xen 4.8 (before upgrade I had Debian 8 "jessie" with Xen 4.4
Hypervisor) and DRBD for High Availability

Everithing works well and I'm able to run all my domU in the hypervisor
just updated but, when I try to migrate one domU to another Host (let be
"host2", that has Debian 8 Jessie and Xen 4.4 Hypervisor and of course
DRBD for High Availability)

it gives me an error:

host1# xl migrate domU host2

usr/lib/xen-4.4/bin/xl: invalid option -- 't'
unknown global option
libxl: error: libxl_utils.c:508:libxl_read_exactly: file/stream
truncated reading banner from migration receiver stream
libxl: info: libxl_exec.c:118:libxl_report_child_exitstatus: migration
transport process [13772] exited with error status 2

If I try the migration from host2 to host1 I get instad:

host2# xl migrate domU host1

migration target: Ready to receive domain.
Saving to migration stream new xl format (info 0x0/0x0/1003)
Loading new save file <incoming migration stream> (new xl fmt info
0x0/0x0/1003)
Savefile contains xl domain config
Parsing config from <saved>
Traceback (most recent call last):
File "/usr/lib/xen-4.8/bin/convert-legacy-stream", line 15, in <module>
from xen.migration import legacy, public, libxc, libxl, xl
ImportError: No module named xen.migration
libxl: error: libxl_stream_read.c:342:stream_header_done: Invalid ident:
expected 0x4c6962786c466d74, got 0x0000000000000000
libxl: error: libxl_utils.c:396:libxl_read_exactly: file/stream
truncated reading ipc msg header from domain 19 save/restore helper
stdout pipe
libxl: error: libxl_exec.c:129:libxl_report_child_exitstatus: domain 19
save/restore helper [-1] died due to fatal signal Broken pipe
migration sender: libxl_domain_suspend failed (rc=-3)
libxl: info: libxl_exec.c:118:libxl_report_child_exitstatus: migration
target process [6462] exited with error status 255
Migration failed, resuming at sender.

Is this normal because the hypervisor has different toolstack version?

I'm just testing these command only to be sure that I will be able to
migrate domU after upgrading my host to Xen 4.8

Thanks in advance

Best regards

Alex

Roger Pau Monné

2018-08-20 08:57:27 UTC

Permalink

Post by Alessandro Tugnoli
Hi all
I've just upgraded my hypervisor (let be "host1") to Debian 9 "Stretch" with
Xen 4.8 (before upgrade I had Debian 8 "jessie" with Xen 4.4 Hypervisor) and
DRBD for High Availability
Everithing works well and I'm able to run all my domU in the hypervisor just
updated but, when I try to migrate one domU to another Host (let be "host2",
that has Debian 8 Jessie and Xen 4.4 Hypervisor and of course DRBD for High
Availability)
host1# xl migrate domU host2
usr/lib/xen-4.4/bin/xl: invalid option -- 't'
unknown global option
libxl: error: libxl_utils.c:508:libxl_read_exactly: file/stream truncated
reading banner from migration receiver stream
libxl: info: libxl_exec.c:118:libxl_report_child_exitstatus: migration
transport process [13772] exited with error status 2
host2# xl migrate domU host1
migration target: Ready to receive domain.
Saving to migration stream new xl format (info 0x0/0x0/1003)
Loading new save file <incoming migration stream> (new xl fmt info
0x0/0x0/1003)
Savefile contains xl domain config
Parsing config from <saved>
File "/usr/lib/xen-4.8/bin/convert-legacy-stream", line 15, in <module>
from xen.migration import legacy, public, libxc, libxl, xl
ImportError: No module named xen.migration
expected 0x4c6962786c466d74, got 0x0000000000000000
libxl: error: libxl_utils.c:396:libxl_read_exactly: file/stream truncated
reading ipc msg header from domain 19 save/restore helper stdout pipe
libxl: error: libxl_exec.c:129:libxl_report_child_exitstatus: domain 19
save/restore helper [-1] died due to fatal signal Broken pipe
migration sender: libxl_domain_suspend failed (rc=-3)
libxl: info: libxl_exec.c:118:libxl_report_child_exitstatus: migration
target process [6462] exited with error status 255
Migration failed, resuming at sender.
Is this normal because the hypervisor has different toolstack version?

Migration to older versions is not supported, albeit it might work.
Only migration between equal or newer versions is supported. Migration
from 4.4 to 4.8 should work, but migration from 4.8 to 4.4 is likely
to fail as you have noted above.

Roger.

Alessandro Tugnoli

2018-08-20 10:17:46 UTC

Permalink

Thank you, i supposed that.
I've asked about migration from older to newer version of hypervisor
because I'm doing an upgrade of my two Xen Hypervisor hosts from xen 4.4
to 4.8 by moving all the VM on the other host before upgrade to avoid
services downtime.
So, to be clear, I started with both hosts with Xen 4.4 and some VM on
host1 and some on host2, so I "live" moved all the VM of host1 to host2
then I've upgraded host1 to xen 4.8 (of course host2 still have xen
4.4) and, after upgrade I would to move back my VM on host1 in order to
proceed to the upgrade of host2 but I've encountered the problem of
migration from older version to a newer of Xen :(

Hope this clarify

So what's the best way to upgrade a cluster with 2 Xen Host without
services downtime ?

thanks in advance
best regards
alex

Post by Roger Pau MonnÃ©

--
***********************************************************************
Dr. Alessandro Tugnoli

ISMN - CNR Area della Ricerca di Bologna
via Gobetti, 101 - 40129 Bologna ITALY

Phone: +39 051 639 8035
Fax: +39 051 639 8130
Email: ***@area.bo.cnr.it
************************************************************************

Roger Pau Monné

2018-08-20 11:04:35 UTC

Permalink

Post by Alessandro Tugnoli
Thank you, i supposed that.
I've asked about migration from older to newer version of hypervisor because
I'm doing an upgrade of my two Xen Hypervisor hosts from xen 4.4 to 4.8 by
moving all the VM on the other host before upgrade to avoid services
downtime.
So, to be clear, I started with both hosts with Xen 4.4 and some VM on host1
and some on host2, so I "live" moved all the VM of host1 to host2 then I've
upgraded host1 to xen 4.8 (of course host2 still have xen 4.4) and, after
upgrade I would to move back my VM on host1 in order to proceed to the
upgrade of host2 but I've encountered the problem of migration from older
version to a newer of Xen :(
Hope this clarify
So what's the best way to upgrade a cluster with 2 Xen Host without services
downtime ?

If both hosts are using the same Xen version you should move
everything to one host, update the now empty host, move all DomUs to
the newly updated host and finally update the remaining host.

Post by Alessandro Tugnoli
thanks in advance
best regards
alex

Can you check that you have /usr/lib/xen-4.8/lib/python/ in your
PYTHONPATH?

You might need something like:

export PYTHONPATH=$PYTHONPATH:/usr/lib/xen-4.8/lib/python/

But I'm no expert on Python.

Roger.

Alessandro Tugnoli

2018-08-20 11:34:06 UTC

Permalink

If both hosts are using the same Xen version you should move
everything to one host, update the now empty host, move all DomUs to
the newly updated host and finally update the remaining host.

yes is what I've tried but the migration fails also from old->new and
that was strange
(i can understand that the migration won't work from new to old of course)

So, by now I had shut down manually all my domUs, reactivated them on
other host (thanks to drbd synchronization of course),
upgrade the server and activated them back again on the upgraded host!

Post by Alessandro Tugnoli
thanks in advance
best regards
alex

Can you check that you have /usr/lib/xen-4.8/lib/python/ in your
PYTHONPATH?
export PYTHONPATH=$PYTHONPATH:/usr/lib/xen-4.8/lib/python/
But I'm no expert on Python.
Roger.

Sure, I hadn't use PYTHONPATH until now but I can try this and see if it
works on next upgrade!

thanks

bye

alex
--
***********************************************************************
Dr. Alessandro Tugnoli

ISMN - CNR Area della Ricerca di Bologna
via Gobetti, 101 - 40129 Bologna ITALY

Phone: +39 051 639 8035
Fax: +39 051 639 8130
Email: ***@area.bo.cnr.it
************************************************************************