LVM and RAID

LVM and RAID

LVM (Logical Volume manager):-

LVM is an extensible partitioning tool using which we can modify or resize any partition without changing our existing data.

/dev/hdax

                                                Figure

/dev/hdax

In order to create LV ( logical volume) we need to create a partition.

#fdisk /dev/had

Press( m for Help): n

l : logical

p : Physical

Type ‘l’

First Cylinder : Press Enter

Last Cylinder (+sizeM or +sizeK) : +100M

Command : t                          : t for change the type

Partition no : x                                   : x is the number of partititon

Type : 8e                                 : 8e for LVM

Command : w

#partprobe

Now we create a Physical Volume (PV)

#pvcreate /dev/hda8

Display the PV Information

#pvdisplay

Now we create Volume group

#vgcreate Vg00 /dev/hda8

Display the Vg information

#vgdisplay

Finally we create a logical volume

#lvcreate –n lv00 –L+50M vg00

Where

-n : logical name

-L: size

Display the LV information

#lvdisplay

After creating the logical volume, we need to format

#mkfs.ext3 /dev/vg00/lv00

Finally we mount it on /lvm

#mkdir /lvm

#mount /dev/vg00/lv00 /lvm

Extending the size of LVM

#lvextend –L+50M /dev/vg00/lv00

After adding we need to run resize2fs command in order to assign file system type to the added size

#resize2fs /dev/vg00/lv00

Reducing the size of LVM

#lvreduce –L-20M /dev/vg00/lv00

If the size of the logical volume is full and we need more space to store data we need to create new partition , change its type to LVM by ‘8e’ then create the physical volume and add that with volume group (vg00)

#vgextend vg00 /dev/hda9

After that extend the size of logical volume

In order to delete the logical volume

#umount /lvm

#lvremove /dev/vg00/lv00

#vgremove vg00

#pvremove /dev/hda9

#pvremove /dev/hda8

Then finally using the fdisk remove hda8 and hda9

 RAID (Redundant Array Of Inexpensive Disk):-

RAID is a series of disk which can save your data even if there is catastrophic failure on one of the disk

RAID are classified as RAID0, RAID1 and RAID 5

RAID 0 : require minimum 2 HDD and also known as stripping without parity

RAID 1: require minimum 2 HDD and also known as disk mirroring

RAID 5: minimum 3 HDD requirement and also known as stripping with parity

First we create the two partition say each of 100MB and then change its type to (‘fd’) Raid

Now we create a RAID

#mdadm –C /dev/md0 –level=1 –raid-disks=2 /dev/hda8 /dev/hda9

Now check the raid

#cat /proc/mdstat

‘OR’

#mdadm --detail /dev/md0

Format the newly created RAID

#mkfs.ext3 /dev/md0

Now mount it

#mkdir /raid

#mount /dev/md0 /raid

In order to check first we fail any one of the partition

#mdadm --manage /dev/md0 --fail /dev/hda8

Check the status of the RAID

#mdadm --detail /dev/md0

Removing the failure partition

#mdadm --manage /dev/md0 --remove /dev/hda8

To add new disk partition

#mdadm --manage /dev/md0 --add /dev/hda10

Note:

In order to add new partition first we create the partition and change  its type to ‘fd’

Thanks ,