Data Migration Using LVM Mirroring

[m3lyan]

http://saharageeks.com/2011/07/26/migrated-data-using-lvm-mirroring/

in the below we will describe how to Migrated Data using Linux LVM ,
and how to change quorum disk

lets assume that We have RHEL 5.4 linux hosts that have volume group:
vgdata
vgdata have 3 PV /dev/mapper/mpath1 /dev/mapper/mpath2 /dev/mapper/
mpath3 each is 100G
and one Logical Volume :lvdata with 250G size.

Where /dev/mapper/mpath1 /dev/mapper/mpath2 /dev/mapper/mpath3 from HP
EVA storage system
and we present 300 GB disk from EMC VNX storage system which is /dev/
mapper/mpath4

we need to migrated data to mpath4, and change quorum disk to /dev/
mapper/mpath5

mpath5 is alos from EMC VNX storage system



so lets dance

1-rescan scsi bus for all HBA

echo “- – -” > /sys/class/scsi_host/host0/scan

2-
#check which disks from EMC VNX and which disks from HP EVA
multipathd -k
show topology

Example below show that mpath0 is 5G disk from IBM
multipathd> show topology
mpath0 (360050768018380367000000000000049) dm-0 IBM,2145
[size=5.0G][features=1 queue_if_no_path][hwhandler=0 ]
\_ round-robin 0 [prio=100][enabled]
\_ 1:0:3:0 sdg 8:96 [active][ready]
\_ 1:0:1:0 sde 8:64 [active][ready]
\_ round-robin 0 [prio=20][enabled]
\_ 1:0:0:0 sda 8:0 [active][ready]
\_ 1:0:2:0 sdc 8:32 [active][ready]
3-

we need to mirror data on logical volume lvdata to mapth4:-



[root@localhost lvdata] pvcreate /dev/mapper/mpath4

Physical volume “/dev/mapper/mpath4″ successfully created

[root@localhost lvdata] vgextend vgdata /dev/mapper/mpath4

Volume group “vgdata” successfully extended

[root@localhost lvdata] vgdisplay -v vgdata # to check PVs insde
vgdata
[root@localhost lvdata] lvconvert -m 1 –corelog vgdata/lvdata /dev/sde

vgdata/lvdata: Converted: 9.5%

vgdata/lvdata: Converted: 25.4%

vgdata/lvdata: Converted: 41.8%

vgdata/lvdata: Converted: 59.9%

vgdata/lvdata: Converted: 73.8%

vgdata/lvdata: Converted: 89.0%

vgdata/lvdata: Converted: 100.0%

Logical volume lvdata converted.

[root@localhost lvdata]



4-

#check mirroring status
[root@localhost ~] lvs

LV VG Attr LSize Origin Snap% Move Log Copy% Convert

lvdata vgdata mwi-ao 25.00G 100.00

[root@localhost ~]

# Once Copying Done 100
#check which PV belong to logical volume lvdata



[root@localhost lvdata] lvs -a -o+devices | grep lvdata

lvdata vgdata mwi-ao 25.00G
100.00 lvdata_mimage_0(0),lvdata_mimage_1(0)

[lvdata_mimage_0] vgdata iwi-ao
25.00G /dev/mapper/mpath1 (0)

[lvdata_mimage_0] vgdata iwi-ao
25.00G /dev/mapper/mpath2 (0)

[lvdata_mimage_0] vgdata iwi-ao
25.00G /dev/mapper/mpath3 (0)

[lvdata_mimage_1] vgdata iwi-ao
25.00G /dev/mapper/mpath4 (0)

[root@localhost lvdata]

## as seen above mpath1,mpath2 and mpath3 make first mirror leg , and
mpath4 make second mirror leg
#split mirror

[root@localhost lvdata] lvconvert -m 0 vgdata/lvdata /dev/mapper/
mpath1 /dev/mapper/mpath2 /dev/mapper/mpath3

Logical volume lvdata converted.

[root@localhost lvdata]

Data Migrated with Zero Downtime

5-

if clustered system and you want to change quorum to mpath5 where
mpath5 is a disk from EMC VNX
[root@localhost lvdata] mkqdis -c /dev/ mapper/mpath5 -l qdisk
edit cluster.conf file

[root@localhost lvdata] vi /etc/cluster.conf
increment version {for example from config_version=”11″ to
config_version=”12″ }
edit quorum device or label in cluster.conf

For example

<quorumd interval=”3″ tko=”23″ votes=”2″ label=”qdisk”>
</quorumd>



Or change device in cluster.conf

<quorumd interval="3" tko="23" votes="2" device= "/dev/mapper/mpath5
">
</quorumd>



save cluster.conf file and exit (wq)
[root@localhost lvdata] ccs_tool update /etc/cluster/cluster.conf
[root@localhost lvdata] cman tool version -r 12



then restart cluster services

#cluster.conf is xml file so be careful while editing this file ,

6- make sure to use defaults 0 0 in /etc/fstab

Enjoy :D

[rami abuoss]

Thanks Musa very nice doc.

 

Rami Abu-Aus

 

---

From: m3lyan <mou...@gmail.com>
To: Jolug <jo...@googlegroups.com>
Sent: Tue, July 26, 2011 11:21:08 PM
Subject: [JoLUG-General] Data Migration Using LVM Mirroring

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[m3lyan]

Hi Rami ,
Kefak ya man . wala zman 3nak

> ### Jordan Linux Users Group ###http://Jolug.org/http://groups.google.com/group/Jolug