Below is the Practical steps of LVM concept:
1. Create 3 partition of size 200MB, 300MB, and 400MB
2. Convert the partition into physical volumes
3. Combine the first 2 physical volumes (200MB, and 300MB)
into a volume group.
4. Create a logical volume from this volume group of size 450MB.
****************************************************
Last login: Tue Mar 8 21:45:12 2016 from 192.168.224.1
[root@keshavkummari ~]#
[root@keshavkummari ~]# fdisk -l
Disk /dev/sda: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000a1858
Device Boot Start End Blocks Id System
/dev/sda1 * 1 39 307200 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 39 914 7031808 83 Linux
Partition 2 does not end on cylinder boundary.
/dev/sda3 914 1045 1048576 82 Linux swap / Solaris
Disk /dev/sdb: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xb6683521
Device Boot Start End Blocks Id System
/dev/sdb1 1 14 112423+ 83 Linux
/dev/sdb2 15 15 8032+ 83 Linux
/dev/sdb3 16 16 8032+ 83 Linux
Disk /dev/sdc: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xde3e26fe
Device Boot Start End Blocks Id System
/dev/sdc1 1 1 8001 83 Linux
[root@keshavkummari ~]#
[root@keshavkummari ~]# fdisk /dev/sdc
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (2-130, default 2):
Using default value 2
Last cylinder, +cylinders or +size{K,M,G} (2-130, default 130): +200M
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 3
First cylinder (28-130, default 28):
Using default value 28
Last cylinder, +cylinders or +size{K,M,G} (28-130, default 130): +200M
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Selected partition 4
First cylinder (54-130, default 54):
Using default value 54
Last cylinder, +cylinders or +size{K,M,G} (54-130, default 130): +300M
Command (m for help): p
Disk /dev/sdc: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xde3e26fe
Device Boot Start End Blocks Id System
/dev/sdc1 1 1 8001 83 Linux
/dev/sdc2 2 27 208845 83 Linux
/dev/sdc3 28 53 208845 83 Linux
/dev/sdc4 54 92 313267+ 83 Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@keshavkummari ~]# partprobe /dev/sdc
*********************************************************
Step 1: Create physical volumes:
Syntax: pvcreate <partition1> <partition2> <partition3>
*********************************************************
[root@keshavkummari ~]# pvcreate /dev/sdc2 /dev/sdc3 /dev/sdc4
Physical volume "/dev/sdc2" successfully created
Physical volume "/dev/sdc3" successfully created
Physical volume "/dev/sdc4" successfully created
*********************************************************
Step 2: To see the physical volumes:
*********************************************************
[root@keshavkummari ~]# pvdisplay or pvs
"/dev/sdc2" is a new physical volume of "203.95 MiB"
--- NEW Physical volume ---
PV Name /dev/sdc2
VG Name
PV Size 203.95 MiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID XGcKMj-T11u-kZ4d-N2UA-NdrJ-cuNI-oE3Ttp
"/dev/sdc3" is a new physical volume of "203.95 MiB"
--- NEW Physical volume ---
PV Name /dev/sdc3
VG Name
PV Size 203.95 MiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID 4xWrEA-zhpS-6KII-5kOb-jO21-9mGF-Pzlwgg
"/dev/sdc4" is a new physical volume of "305.93 MiB"
--- NEW Physical volume ---
PV Name /dev/sdc4
VG Name
PV Size 305.93 MiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID aqKZ8V-nniQ-4pUS-OfwY-jKmm-CktX-pcCVB4
*********************************************************
Step 3: Create a volume group
Syntax: vgcreate <volume_group_name> <physical_volume1> <physical_volume2>
*********************************************************
[root@keshavkummari ~]# vgcreate data /dev/sdc2 /dev/sdc3
Volume group "data" successfully created
*********************************************************
Step 4: To see the volume group :
*********************************************************
[root@keshavkummari ~]# vgdisplay
--- Volume group ---
VG Name data
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 1
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 0
Open LV 0
Max PV 0
Cur PV 2
Act PV 2
VG Size 400.00 MiB
PE Size 4.00 MiB
Total PE 100
Alloc PE / Size 0 / 0
Free PE / Size 100 / 400.00 MiB
VG UUID S5L3xc-tasb-JL69-jPNG-gRib-lSfA-Kw1s3y
*********************************************************
Step 5: Create a logical volume
Syntax: lvcreate -L <size> <volume_group_name> -n <logical volume name>
*********************************************************
[root@keshavkummari ~]# lvcreate -L 150mb data -n backupdata
Rounding up size to full physical extent 152.00 MiB
Logical volume "backupdata" created
*********************************************************
Step 6: To see the logical volume:
*********************************************************
[root@keshavkummari ~]# lvdisplay or lvs
--- Logical volume ---
LV Path /dev/data/backupdata
LV Name backupdata
VG Name data
LV UUID tcOHbt-MTDv-jVgV-ftgC-mVfa-SySR-PW5Ye9
LV Write Access read/write
LV Creation host, time keshavkummari.localdomain, 2016-03-08 23:30:07 -0800
LV Status available
# open 0
LV Size 152.00 MiB
Current LE 38
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
*********************************************************
Step 7: Format the logical volume and mount it:
*********************************************************
[root@keshavkummari ~]# mkfs.ext3 /dev/data/backupdata
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
38912 inodes, 155648 blocks
7782 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
19 block groups
8192 blocks per group, 8192 fragments per group
2048 inodes per group
Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729
Writing inode tables: done
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 37 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@keshavkummari ~]# mkdir /backup
[root@keshavkummari ~]# mount /dev/data/backupdata /backup/
*********************************************************
Step 8:
1. The size of the logical volume is to be increased by 400MB.
2. The volume group does not have sufficient free space.
So first extend the volume group.
Extending the volume group:
Syntax: vgextend <volume_group_name> <physical_volume_name>
*********************************************************
[root@keshavkummari ~]# vgextend data /dev/sdc3
Physical volume '/dev/sdc3' is already in volume group 'data'
Unable to add physical volume '/dev/sdc3' to volume group 'data'.
*********************************************************
Step 9: Resizing the logical value:
Syntax: lvresize -L <+size> <logical_volume_name>
*********************************************************
To extend the logical volume by 200MB:
[root@keshavkummari ~]# lvresize -L +200M /dev/data/backupdata
Extending logical volume backupdata to 352.00 MiB
Logical volume backupdata successfully resized
Resize the filesystem:
**********************
[root@keshavkummari ~]# resize2fs /dev/data/backupdata
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/data/backupdata is mounted on /backup; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 2
Performing an on-line resize of /dev/data/backupdata to 360448 (1k) blocks.
The filesystem on /dev/data/backupdata is now 360448 blocks long.
*********************************************************
Step 10: To see the logical volume:
*********************************************************
[root@keshavkummari ~]# lvdisplay
--- Logical volume ---
LV Path /dev/data/backupdata
LV Name backupdata
VG Name data
LV UUID tcOHbt-MTDv-jVgV-ftgC-mVfa-SySR-PW5Ye9
LV Write Access read/write
LV Creation host, time keshavkummari.localdomain, 2016-03-08 23:30:07 -0800
LV Status available
# open 1
LV Size 352.00 MiB
Current LE 88
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
*********************************************************
Step 11: Removing the logical volume:
Syntax: lvremove <logical_volume_name>
*********************************************************
[root@keshavkummari ~]# umount /backup/
[root@keshavkummari ~]# lvremove /dev/data/backupdata
Do you really want to remove active logical volume backupdata? [y/n]: n
Logical volume backupdata not removed
Note: If "y"
then : Logical volume backupdata has been removed successfully.
*********************************************************
NOTE : LVREDUCE IS NOT WORK WITH XFS FILES SYSTEM
Stpe 12: Reducing Logical Volume (LVM)
*********************************************************
To Reduce a logical volume there are 5 steps needed to be done very carefully.
While extending a volume we can extend it while the volume under mount status (online),
but for reduce we must need to unmount the file system before reducing.
5 steps below:
1. unmount the file system for reducing.
[root@keshavkummari ~]# umount /backup/
2. Check the file system after unmount.
[root@keshavkummari ~]# e2fsck -ff /dev/data/backupdata
[root@server ~]# e2fsck -ff /dev/data/backupdata
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/data/backupdata: 11/13328 files (9.1% non-contiguous), 6823/53248 blocks
Note: Must pass in every 5 steps of file-system check if not there might be
some issue with your file-system.
3. Reduce the file system.
[root@server ~]# resize2fs /dev/data/backupdata
resize2fs 1.42.9 (28-Dec-2013)
The filesystem is already 53248 blocks long. Nothing to do!
4. Reduce the Logical Volume size than Current size.
[root@server ~]# lvreduce -L -20M /dev/data/backupdata
Logical volume lvm-minnu successfully resized
5. Recheck the file system for error.
[root@server ~]# e2fsck -ff /dev/data/backupdata
6. Remount the file-system back to stage.
[root@server ~]# mount /dev/data/backupdata /backup
******************** Keshav Kummari ********************
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