CentOS 5
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Migration
  This is the section to use migration function of Xen. It's easy to make GuestOS migrate to another computer with this function.

At least 2 computers are needed if you use this function. (But It's the best if you use 3 computers if possible) Anyway, I can't use 3 computers, so I did migration with 2 computers on here.

First, Create the same environment with primary computer in second computer and mount a directory with NFS that image-file of GuestOS is located in primary computer.

[1] Configure on primary computer
[root@ns ~]#
vi /etc/exports


/home 192.168.0.0/24(rw,sync,no_root_squash)
# add

/var/xen 192.168.0.0/24(rw,sync,no_root_squash)


[root@ns ~]#
/etc/rc.d/init.d/nfs restart

Shutting down NFS mountd:
  [  OK  ]

Shutting down NFS daemon:
  [  OK  ]

Shutting down NFS quotas:
  [  OK  ]

Shutting down NFS services:
  [  OK  ]

Starting nfs services:
  [  OK  ]

Starting nfs quotas:
  [  OK  ]

Starting nfs daemon:
  [  OK  ]

Starting nfs mountd:
  [  OK  ]

[root@ns ~]#
vi /etc/xen/xend-config.sxp


# line 21: make valid and change to 'yes'

(xend-relocation-server
yes
)

# line 33: uncomment

(xend-relocation-port 8002)

# line 58: uncomment

(xend-relocation-hosts-allow '')

# line 59: make it comment

#
(xend-relocation-hosts-allow '^localhost$ ^localhost\\.localdomain$')

[root@ns ~]#
/etc/rc.d/init.d/xend restart

restart xend:
  [  OK  ]
[2] Configure on secondary computer
[root@ns ~]#
xm list

Name
ID
Mem(MiB)
VCPUs
State
Time(s)

Host2
0
510
2
r-----
12.6


[root@ns ~]#
mkdir /var/xen

[root@ns ~]#
mount -t nfs 192.168.0.17:/var/xen /var/xen

[root@ns ~]#
vi /etc/xen/xend-config.sxp


# line 21: uncomment and change to 'yes'

(xend-relocation-server
yes
)

# line 33: uncomment

(xend-relocation-port 8002)

# line 58: uncomment

(xend-relocation-hosts-allow '')

# line 59: uncomment

#
(xend-relocation-hosts-allow '^localhost$ ^localhost\\.localdomain$')

[root@ns ~]#
/etc/rc.d/init.d/xend restart

restart xend:
  [  OK  ]
[3] Move to Primary computer and Execute migration of GuestOS 'rx7'
[root@ns ~]#
xm list

Name
ID
Mem(MiB)
VCPUs
State
Time(s)

Host
0
510
2
r-----
34.6

lan
3
511
2
r-----
10.8

rx7
4
511
2
r-----
13.9

mail
2
511
2
r-----
19.4

www
1
511
2
r-----
12.3

[root@ns ~]#
xm migrate rx7 192.168.0.105
 
# migration

[root@ns ~]#
xm list

Name
ID
Mem(MiB)
VCPUs
State
Time(s)

Host
0
510
2
r-----
34.6

lan
3
511
2
r-----
10.8

mail
2
511
2
r-----
19.4

www
1
511
2
r-----
12.3

# rx7 has just gone like above
[4] Make sure whether 'rx7' has come or not on secondary computer.
[root@ns ~]#
xm list

Name
ID
Mem(MiB)
VCPUs
State
Time(s)

Host2
0
510
2
r-----
34.6

rx7
2
511
2
r-----
0.1

# Wellcome!
  Migration has been success, however, following errors are displayed. Well, it's not good because CPUs on 2 computers are different. It seems we must use the same CPU on primary and secondary computers if we use migration function.
BUG: soft lockup detected on CPU#1!
[<c043ea7f>] softlockup_tick+0x98/0xa6
[<c0408b7d>] timer_interrupt+0x504/0x557
[<c043ecb3>] handle_IRQ_event+0x27/0x51
[<c043ed70>] __do_IRQ+0x93/0xe8
[<c040672b>] do_IRQ+0x93/0xae
[<c053a095>] evtchn_do_upcall+0x64/0x9b
[<c0404ec5>] hypervisor_callback+0x3d/0x48
[<c0407fd1>] raw_safe_halt+0x8c/0xaf
[<c0402bca>] xen_idle+0x22/0x2e
[<c0402ce9>] cpu_idle+0x91/0xab
=======================
[root@ns ~]#
xm migrate rx7 192.168.0.17

[root@ns ~]#
xm list

Name
ID
Mem(MiB)
VCPUs
State
Time(s)

Host2
0
510
2
r-----
36.3

[5] If you don't want to kill network connection at all, use Live-Migration. It's easy to use it. Execute the command 'xm migrate --live'.
//////////// Primary Computer ////////////

[root@ns ~]#
xm list

Name
ID
Mem(MiB)
VCPUs
State
Time(s)

Host
0
510
2
r-----
34.6

lan
3
511
2
r-----
10.8

rx7
4
511
2
r-----
13.9

mail
2
511
2
r-----
19.4

www
1
511
2
r-----
12.3

[root@ns ~]#
xm migrate --live rx7 192.168.0.105

[root@ns ~]#
xm list

Name
ID
Mem(MiB)
VCPUs
State
Time(s)

Host
0
510
2
r-----
34.6

lan
3
511
2
r-----
10.8

mail
2
511
2
r-----
19.4

www
1
511
2
r-----
12.3


//////////// Secondary Computer ////////////

[root@ns ~]#
xm list

Name
ID
Mem(MiB)
VCPUs
State
Time(s)

Host2
0
510
2
r-----
34.6

rx7
2
511
2
r-----
0.1

[root@ns ~]#
xm migrate --live rx7 192.168.0.17

[root@ns ~]#
xm list

Name
ID
Mem(MiB)
VCPUs
State
Time(s)

Host2
0
510
2
r-----
51.6


//////////// Primary Computer ////////////

[root@ns ~]#
xm list

Name
ID
Mem(MiB)
VCPUs
State
Time(s)

Host
0
510
2
r-----
34.6

lan
3
511
2
r-----
10.8

rx7
4
511
2
r-----
13.9

mail
2
511
2
r-----
19.4

www
1
511
2
r-----
12.3

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