System Admin Questions 3

Q: - Can we resize the size of a partition?
Yes, we can resize the size of partition by “parted” command.
#parted /dev/sda

print

To resize the partition, use the resize command followed by the minor number for the partition, the starting place in megabytes, and the end place in megabytes. For example:

resize 3 1024 2048

After resizing the partition, use the print command to confirm that the partition has been resized correctly, is the correct partition type, and is the correct file system type.

Q: - What is LVM?
LVM stands for Logical Volume Manager. LVM, is a storage management solution that allows administrators to divide hard drive space into physical volumes (PV), which can then be combined into logical volume groups (VG), which are then divided into logical volumes (LV) on which the filesystem and mount point are created.  

Q: - What are the steps to create LVM?
- Create physical volumes by “pvcreate” command

#pvcreate /dev/sda2
- Add physical volume to volume group by “vgcreate” command

#vgcreate VLG0 /dev/sda2
- Create logical volume from volume group by “lvcreate” command.

#lvcreate -L 1G -n LVM1 VLG0
Now create file system on /dev/sda2 partition by “mke2fs” command.

#mke2fs -j /dev/VLG0/LVM1

Q: - What is the difference between LVM and RAID?
RAID provides redundancy but LVM doesn’t provide Redundancy.

Q: - What are LVM1 and LVM2?
LVM1 and LVM2 are the versions of LVM.
LVM2 uses device mapper driver contained in 2.6 kernel version.
LVM 1 was included in the 2.4 series kernels.

Q: - What is Volume group (VG)?
The Volume Group is the highest level abstraction used within the LVM. It gathers together a collection of Logical Volumes and Physical Volumes into one administrative unit.

Q: - What is physical extent (PE)?
Each physical volume is divided chunks of data, known as physical extents; these extents have the same size as the logical extents for the volume group.

Q: - What is logical extent (LE)?
Each logical volume is split into chunks of data, known as logical extents. The extent size is the same for all logical volumes in the volume group.

Q: - Explain LVM snapshot?
LVM snapshots allow the administrator to create a new block device which presents an exact copy of a logical volume, frozen at some point in time.

Q: - How you will check on Your server or system device-mapper is installed or not?
Check the following file.
#cat /proc/misc

if this file contains "device-mapper" term it means device mapper is installed on your system.

Q: - How are snapshots in LVM2 different from LVM1?
In LVM2 snapshots are read/write by default, whereas in LVM1, snapshots were read only.

Q: - What is the maximum size of a single LV?
For 2.4 based kernels, the maximum LV size is 2TB.
For 32-bit CPUs on 2.6 kernels, the maximum LV size is 16TB.
For 64-bit CPUs on 2.6 kernels, the maximum LV size is 8EB.

Q: - If a volume group named as VG0 already exists but i need to extend this volume group up to 4GB.Explain all steps?
Firstly create Physical volume (/dev/sda7) of size 4GB.

Now run following command.
vgextend VG0 /dev/sda7

Q: - If a volume group VG0 have 3 PV's (/dev/sda6, /dev/sda7, /dev/sda8) but i want to remove /dev/sda7 pv from this VG0?
vgreduce VG0 /dev/sda7

Q: - Which command is used to extend a logical volume?
lvextend --size + /dev//

resize2fs /dev//

Q: - Tell me all steps to remove a LVM?
To remove a logical volume from a volume group, first unmount it with the umount command:

umount /dev//

and then use the lvremove command:

lvremove /dev/

For more Questions click here