Tuesday, 10 July 2012

Unix/Linux System Admin Interview Questions And Answers 4

Q: - Tell me the steps to remove the swap file?

Firstly disable the swap file by “swapoff” command.
Remove Swap file entry from /etc/fstab file.
Now remove the swap file by “rm” command.

Q: - What can we do with “parted” command or utility?

- View the existing partition table
- Add partitions from free space or additional hard drives
- Change the size of existing partitions

Q: - How we will check free space on drive /dev/sda with parted command?

#parted /dev/sda
Q: - Can we resize the size of a partition?

Yes, we can resize the size of partition by “parted” command.
#parted /dev/sda
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.

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