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1. Introduction

  1. Q: What is RAID?
    A: RAID stands for "Redundant Array of Inexpensive Disks", and is meant to be a way of creating a fast and reliable disk-drive subsystem out of individual disks.
  2. Q: What is this document?
    A: This document is a tutorial/HOWTO/FAQ for users of the Linux MD kernel extension, the associated tools, and their use. The MD extension implements RAID-0 (stripping), RAID-1 (mirroring), RAID-4 and RAID-5 in software. That is, with MD, no special hardware or disk controllers are required to get many of the benefits of RAID. This document is NOT an introduction to RAID; you must find this elsewhere.
  3. Q: What levels of RAID does the Linux kernel implement?
    A: Striping (RAID-0) and linear concatenation are a part of the stock 2.x series of kernels. This code is of production quality; it is well understood and well maintained. It is being used in some very large USENET news servers. RAID-1, RAID-4 & RAID-5 are not present in the stock kernel; a separate patch needs to be applied to get this functionality. The current snapshots should be considered beta quality; that is, there are no known bugs but there are some rough edges and untested system setups. RAID-1 hot reconstruction has been recently introduced (August 1997) and should be considered alpha quality. RAID-5 hot reconstruction will be alpha quality any day now.
  4. Q: Where do I get it?
    A: Software RAID-0 and linear mode are a stock part of all current Linux kernels. Patches for Software RAID-1,4,5 are available from http://luthien.nuclecu.unam.mx/~miguel/raid. See also the quasi-mirror ftp://linux.kernel.org/pub/linux/daemons/raid/ for patches, tools and other goodies.
  5. Q: Are there other Linux RAID references?
    A:
  6. Q: Who do I blame for this document?
    A: Linas Vepstas slapped this thing together. However, most of the information, and some of the words were supplied by

    Copyrights

    • Copyright (C) 1994-96 Marc ZYNGIER
    • Copyright (C) 1997 Gadi Oxman, Ingo Molnar, Miguel de Icaza
    • Copyright (C) 1997 Linas Vepstas
    • By copyright law, additional copyrights are implicitly held by the contributors listed above.

    Thanks all for being there!


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