LVM / Logical Volume Manager

LVM / Logical Volume Manager
LVM / Logical Volume Manager

It can be said as a thin software layer on top of the hard drives and partitions, which creates illusion of continuity and easy of use for managing hard drives replacement, re-partitioning and backups.

It’s common usages are to manage large drives farm by adding a disk, replacing a disk, copy and share the disks without interrupting services running. For small setups there is no need to worry about partition size offering for requirements in future as disks partition can be re-sized easily on run-time, further making backups by taking snapshots and creating single logical volume of multiple physical volumes or entire hard disks functionality is also available.

Features of LVM

  • Re-size volume groups
  • Re-size logical volumes
  • Create read-only snapshot – LVM1
  • Create read-write snapshot – LVM2
  • Strips whole or parts of logical volumes (similar Raid0)
  • Mirror whole or parts of logical volumes (similar Raid1)
  • Move online logical volumes
  • Split or merge volume groups

Almost features can be performed online without disrupting users.

File Types & I/O Rediction

I/O
I/O

I was has having problem in recognizing file types in my studies, therefore to learn I searched and read few documents and found these types under Unix / Linux:-

  • (-) – ASCII/ordinary files
  • (d) – Directories
  • (c) – Character Special Files
  • (b) – Block Special Files
  • (p) – FIFO Files or Pipes

Further everything which carry down with Input Output Redirection over entire Unix / Linux is followed by

  • Standard Input – “0” – Keyboard
  • Standard Output – “1” – Terminal / Display
  • Standard Error – “2” – Terminal / Display

Note:- It will be pleasure if someone would like to contribute more to this post