Thursday, 30 January 2014


Most of the time we used to get the task for creating the New Logical Volume in Redhat Linux. Here is the Step by step procedure for adding the disk into Linux Server. Let we can start with our high level plan.

High Level Plan:
1. Identify the New Disk.
2. Create a Physical volume.
3. Create a Volume group.
4. Create a Logical volume.
5. Create a Filesystem on the Logical Volume.
6. Create a Mountpoint and Mount the Logical Volume.
7. Add the entry in /etc/fstab for presist mount.

Checking the currently available disk with using fdisk command
[root@unixrock /]# fdisk -l

Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 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: 0x000d0e67

   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         549     4096000   82  Linux swap / Solaris
Partition 2 does not end on cylinder boundary.
/dev/sda3             549        2611    16567296   83  Linux

Disk /dev/mapper/vg01-LVOL1: 25 MB, 25165824 bytes
255 heads, 63 sectors/track, 3 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: 0x00000000
[root@unixrock /]#
Before Scanning disks we can check the available host scsi connection
[root@unixrock ~]# cat /proc/scsi/scsi
Attached devices:
Host: scsi1 Channel: 00 Id: 00 Lun: 00
  Vendor: NECVMWar Model: VMware IDE CDR10 Rev: 1.00
  Type:   CD-ROM                           ANSI  SCSI revision: 05
Host: scsi2 Channel: 00 Id: 00 Lun: 00
  Vendor: VMware,  Model: VMware Virtual S Rev: 1.0
  Type:   Direct-Access                    ANSI  SCSI revision: 02
[root@unixrock ~]#
from the above output we can see 2 Host scsi connection (One is CDROM, another one is Disk) are present respectively. Now Scanning the new disk
[root@unixrock ~]# echo "- - -" >/sys/class/scsi_host/host2/scan
[root@unixrock ~]#
scanned "host2" according to the "cat /proc/scsi/scsi" output. Checking new disk availability.
[root@unixrock /]# fdisk -l

Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 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: 0x000d0e67

   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         549     4096000   82  Linux swap / Solaris
Partition 2 does not end on cylinder boundary.
/dev/sda3             549        2611    16567296   83  Linux

Disk /dev/mapper/vg01-LVOL1: 25 MB, 25165824 bytes
255 heads, 63 sectors/track, 3 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: 0x00000000


Disk /dev/sdb: 234 MB, 234881024 bytes
8 heads, 56 sectors/track, 1024 cylinders
Units = cylinders of 448 * 512 = 229376 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x8cb5a280

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1         100       22372   83  Linux

Disk /dev/sde: 234 MB, 234881024 bytes
8 heads, 56 sectors/track, 1024 cylinders
Units = cylinders of 448 * 512 = 229376 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x2d576e29

   Device Boot      Start         End      Blocks   Id  System
/dev/sde1               1         100       22372   83  Linux
[root@unixrock /]#
Now we can see 2 Newdisks (/dev/sdb;/dev/sde) has been added. let we can start working on LVM part
Creating Physical Volume
[root@unixrock ~]# pvcreate /dev/sdb1
  Writing physical volume data to disk "/dev/sdb1"
  Physical volume "/dev/sdb1" successfully created
[root@unixrock ~]# 
[root@unixrock ~]# pvs
  PV         VG   Fmt  Attr PSize  PFree
  /dev/sdb1       lvm2 a--  21.85m 21.85m
[root@unixrock ~]#
Creating new Volume group
[root@unixrock ~]# vgcreate vg01 /dev/sdb1
  Volume group "vg01" successfully created
[root@unixrock ~]#
[root@unixrock ~]# vgs
  VG   #PV #LV #SN Attr   VSize  VFree
  vg01   1   0   0 wz--n- 20.00m 20.00m
[root@unixrock ~]#
Creating Logical Volume
[root@unixrock ~]# lvcreate -L 10M -n LVOL1 vg01
  Rounding up size to full physical extent 12.00 MiB
  Logical volume "LVOL1" created
[root@unixrock ~]#
Creating New Filesystem
[root@unixrock ~]# mkfs.ext4 /dev/vg01/LVOL1
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
3072 inodes, 12288 blocks
614 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=12582912
2 block groups
8192 blocks per group, 8192 fragments per group
1536 inodes per group
Superblock backups stored on blocks:
        8193

Writing inode tables: done
Creating journal (1024 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 28 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
[root@unixrock ~]#
Creating Mount point and mounting the logical Volume.
[root@unixrock ~]# mkdir /LVOL1_mnt
[root@unixrock ~]# mount /dev/vg01/LVOL1 /LVOL1_mnt
[root@unixrock ~]# 
[root@unixrock ~]# df -h /LVOL1_mnt
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg01-LVOL1
                       12M  1.2M   10M  11% /LVOL1_mnt
[root@unixrock ~]#
Cool...!!!! We have successfully get the newdisk into LVM control.

I hope this Post will help you whenever you getting the similar request. Please leave your valuable comments and queries, I will get back to you at earliest.