A Beginner's Guide To LVM - Page 7
Afterwards we prepare /dev/md0 and /dev/md1 for LVM:
pvcreate /dev/md0 /dev/md1
server1:~# pvcreate /dev/md0 /dev/md1
Physical volume "/dev/md0" successfully created
Physical volume "/dev/md1" successfully created
and extend our fileserver volume group:
vgextend fileserver /dev/md0 /dev/md1
server1:~# vgextend fileserver /dev/md0 /dev/md1
Volume group "fileserver" successfully extended
The outputs of
pvdisplay
and
vgdisplay
should look like this:
server1:~# pvdisplay
--- Physical volume ---
PV Name /dev/sdb1
VG Name fileserver
PV Size 23.29 GB / not usable 0
Allocatable yes (but full)
PE Size (KByte) 4096
Total PE 5961
Free PE 0
Allocated PE 5961
PV UUID USDJyG-VDM2-r406-OjQo-h3eb-c9Mp-4nvnvu
--- Physical volume ---
PV Name /dev/sdd1
VG Name fileserver
PV Size 23.29 GB / not usable 0
Allocatable yes
PE Size (KByte) 4096
Total PE 5961
Free PE 146
Allocated PE 5815
PV UUID qdEB5d-389d-O5UA-Kbwv-mn1y-74FY-4zublN
--- Physical volume ---
PV Name /dev/md0
VG Name fileserver
PV Size 23.29 GB / not usable 0
Allocatable yes
PE Size (KByte) 4096
Total PE 5961
Free PE 5961
Allocated PE 0
PV UUID 7JHUXF-1R2p-OjbJ-X1OT-uaeg-gWRx-H6zx3P
--- Physical volume ---
PV Name /dev/md1
VG Name fileserver
PV Size 23.29 GB / not usable 0
Allocatable yes
PE Size (KByte) 4096
Total PE 5961
Free PE 5961
Allocated PE 0
PV UUID pwQ5AJ-RwVK-EebA-0Z13-d27d-2IdP-HqT5RW
server1:~# vgdisplay
--- Volume group ---
VG Name fileserver
System ID
Format lvm2
Metadata Areas 4
Metadata Sequence No 14
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 4
Act PV 4
VG Size 93.14 GB
PE Size 4.00 MB
Total PE 23844
Alloc PE / Size 11776 / 46.00 GB
Free PE / Size 12068 / 47.14 GB
VG UUID dQDEHT-kNHf-UjRm-rmJ3-OUYx-9G1t-aVskI1
Now we move the contents of /dev/sdb1 to /dev/md0 and the contents of /dev/sdd1 to /dev/md1, then we remove /dev/sdb1 and /dev/sdd1 from LVM:
pvmove /dev/sdb1 /dev/md0
pvmove /dev/sdd1 /dev/md1
vgreduce fileserver /dev/sdb1 /dev/sdd1
pvremove /dev/sdb1 /dev/sdd1
Now only /dev/md0 and /dev/md1 should be left as physical volumes:
pvdisplay
server1:~# pvdisplay
--- Physical volume ---
PV Name /dev/md0
VG Name fileserver
PV Size 23.29 GB / not usable 0
Allocatable yes (but full)
PE Size (KByte) 4096
Total PE 5961
Free PE 0
Allocated PE 5961
PV UUID 7JHUXF-1R2p-OjbJ-X1OT-uaeg-gWRx-H6zx3P
--- Physical volume ---
PV Name /dev/md1
VG Name fileserver
PV Size 23.29 GB / not usable 0
Allocatable yes
PE Size (KByte) 4096
Total PE 5961
Free PE 146
Allocated PE 5815
PV UUID pwQ5AJ-RwVK-EebA-0Z13-d27d-2IdP-HqT5RW
Now we format /dev/sdb1 with fd (Linux RAID autodetect):
fdisk /dev/sdb
server1:~# fdisk /dev/sdb
The number of cylinders for this disk is set to 32635.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Command (m for help): <-- m
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)
Command (m for help): <-- t
Selected partition 1
Hex code (type L to list codes): <-- fd
Changed system type of partition 1 to fd (Linux raid autodetect)
Command (m for help): <-- w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
Do the same with /dev/sdd1:
fdisk /dev/sdd
Next add /dev/sdb1 to /dev/md0 and /dev/sdd1 to /dev/md1:
mdadm --manage /dev/md0 --add /dev/sdb1
server1:~# mdadm --manage /dev/md0 --add /dev/sdb1
mdadm: added /dev/sdb1
mdadm --manage /dev/md1 --add /dev/sdd1
server1:~# mdadm --manage /dev/md1 --add /dev/sdd1
mdadm: added /dev/sdd1
Now the two RAID arrays will be synchronized. This will take some time, you can check with
cat /proc/mdstat
when the process is finished. The output looks like this for an unfinished process:
server1:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid5] [raid4] [raid6] [raid10]
md1 : active raid1 sdd1[2] sde1[0]
24418688 blocks [2/1] [U_]
[=>...................] recovery = 6.4% (1586560/24418688) finish=1.9min speed=198320K/sec
md0 : active raid1 sdb1[2] sdc1[0]
24418688 blocks [2/1] [U_]
[==>..................] recovery = 10.5% (2587264/24418688) finish=2.8min speed=129363K/sec
unused devices: <none>
and like this when the process is finished:
server1:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid5] [raid4] [raid6] [raid10]
md1 : active raid1 sdd1[1] sde1[0]
24418688 blocks [2/2] [UU]
md0 : active raid1 sdb1[1] sdc1[0]
24418688 blocks [2/2] [UU]
unused devices: <none>
If you have a look at PV Size in the output of
pvdisplay
you will see that 2 * 23.29GB = 46.58GB are available, however only 40GB (share) + 5GB (backup) + 1GB (media) = 46GB are used which means we could extend one of our logical devices with about 0.5GB. I've already shown how to extend an ext3 logical volume (share), so we will resize media now which uses reiserfs. reiserfs filesystems can be resized without unmounting:
lvextend -L1.5G /dev/fileserver/media
server1:~# lvextend -L1.5G /dev/fileserver/media
Extending logical volume media to 1.50 GB
Logical volume media successfully resized
resize_reiserfs /dev/fileserver/media
server1:~# resize_reiserfs /dev/fileserver/media
resize_reiserfs 3.6.19 (2003 www.namesys.com)
resize_reiserfs: On-line resizing finished successfully.
The output of
df -h
looks like this:
server1:~# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 19G 666M 17G 4% /
tmpfs 78M 0 78M 0% /lib/init/rw
udev 10M 92K 10M 1% /dev
tmpfs 78M 0 78M 0% /dev/shm
/dev/sda1 137M 17M 114M 13% /boot
/dev/mapper/fileserver-share
40G 177M 38G 1% /var/share
/dev/mapper/fileserver-backup
5.0G 144K 5.0G 1% /var/backup
/dev/mapper/fileserver-media
1.5G 33M 1.5G 3% /var/media
If we want our logical volumes to be mounted automatically at boot time, we must modify /etc/fstab again (like in chapter 3):
mv /etc/fstab /etc/fstab_orig
cat /dev/null > /etc/fstab
vi /etc/fstab
Put the following into it:
# /etc/fstab: static file system information. # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc defaults 0 0 /dev/sda2 / ext3 defaults,errors=remount-ro 0 1 /dev/sda1 /boot ext3 defaults 0 2 /dev/hdc /media/cdrom0 udf,iso9660 user,noauto 0 0 /dev/fd0 /media/floppy0 auto rw,user,noauto 0 0 /dev/fileserver/share /var/share ext3 rw,noatime 0 0 /dev/fileserver/backup /var/backup xfs rw,noatime 0 0 /dev/fileserver/media /var/media reiserfs rw,noatime 0 0 |
If you compare it to our backup of the original file, /etc/fstab_orig, you will notice that we added the lines:
/dev/fileserver/share /var/share ext3 rw,noatime 0 0
/dev/fileserver/backup /var/backup xfs rw,noatime 0 0
/dev/fileserver/media /var/media reiserfs rw,noatime 0 0
Now we reboot the system:
shutdown -r now
After the system has come up again, run
df -h
again. It should still show our logical volumes in the output:
server1:~# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 19G 666M 17G 4% /
tmpfs 78M 0 78M 0% /lib/init/rw
udev 10M 100K 10M 1% /dev
tmpfs 78M 0 78M 0% /dev/shm
/dev/sda1 137M 17M 114M 13% /boot
/dev/mapper/fileserver-share
40G 177M 38G 1% /var/share
/dev/mapper/fileserver-backup
5.0G 144K 5.0G 1% /var/backup
/dev/mapper/fileserver-media
1.5G 33M 1.5G 3% /var/media
Now we are finished with our LVM on RAID1 setup.
