228 lines
8.2 KiB
HTML
228 lines
8.2 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
|
|
<HTML>
|
|
<HEAD>
|
|
<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
|
|
<TITLE>Software-RAID HOWTO: Introduction</TITLE>
|
|
<LINK HREF="Software-RAID-0.4x-HOWTO-2.html" REL=next>
|
|
|
|
<LINK HREF="Software-RAID-0.4x-HOWTO.html#toc1" REL=contents>
|
|
</HEAD>
|
|
<BODY>
|
|
<A HREF="Software-RAID-0.4x-HOWTO-2.html">Next</A>
|
|
Previous
|
|
<A HREF="Software-RAID-0.4x-HOWTO.html#toc1">Contents</A>
|
|
<HR>
|
|
<H2><A NAME="s1">1. Introduction</A></H2>
|
|
|
|
<P>
|
|
<OL>
|
|
<LI><B>Q</B>:
|
|
What is RAID?
|
|
<BLOCKQUOTE>
|
|
<B>A</B>:
|
|
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. In the PC world, "I" has come to
|
|
stand for "Independent", where marketing forces continue to
|
|
differentiate IDE and SCSI. In it's original meaning, "I" meant
|
|
"Inexpensive as compared to refrigerator-sized mainframe
|
|
3380 DASD", monster drives which made nice houses look cheap,
|
|
and diamond rings look like trinkets.
|
|
</BLOCKQUOTE>
|
|
|
|
</LI>
|
|
<LI><B>Q</B>:
|
|
What is this document?
|
|
<BLOCKQUOTE>
|
|
<B>A</B>:
|
|
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 (striping), 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.
|
|
|
|
<P>This document is <B>NOT</B> an introduction to RAID;
|
|
you must find this elsewhere.
|
|
</BLOCKQUOTE>
|
|
|
|
</LI>
|
|
<LI><B>Q</B>:
|
|
What levels of RAID does the Linux kernel implement?
|
|
<BLOCKQUOTE>
|
|
<B>A</B>:
|
|
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.
|
|
|
|
<P>RAID-1, RAID-4 & RAID-5 are a part of the 2.1.63 and greater
|
|
kernels. For earlier 2.0.x and 2.1.x kernels, patches exist
|
|
that will provide this function. Don't feel obligated to
|
|
upgrade to 2.1.63; upgrading the kernel is hard; it is *much*
|
|
easier to patch an earlier kernel. Most of the RAID user
|
|
community is running 2.0.x kernels, and that's where most
|
|
of the historic RAID development has focused. The current
|
|
snapshots should be considered near-production quality; that
|
|
is, there are no known bugs but there are some rough edges and
|
|
untested system setups. There are a large number of people
|
|
using Software RAID in a production environment.
|
|
<P>
|
|
<P>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.
|
|
<P>
|
|
<P>A word of caution about the 2.1.x development kernels:
|
|
these are less than stable in a variety of ways. Some of
|
|
the newer disk controllers (e.g. the Promise Ultra's) are
|
|
supported only in the 2.1.x kernels. However, the 2.1.x
|
|
kernels have seen frequent changes in the block device driver,
|
|
in the DMA and interrupt code, in the PCI, IDE and SCSI code,
|
|
and in the disk controller drivers. The combination of
|
|
these factors, coupled to cheapo hard drives and/or
|
|
low-quality ribbon cables can lead to considerable
|
|
heartbreak. The <CODE>ckraid</CODE> tool, as well as
|
|
<CODE>fsck</CODE> and <CODE>mount</CODE> put considerable stress
|
|
on the RAID subsystem. This can lead to hard lockups
|
|
during boot, where even the magic alt-SysReq key sequence
|
|
won't save the day. Use caution with the 2.1.x kernels,
|
|
and expect trouble. Or stick to the 2.0.34 kernel.
|
|
</BLOCKQUOTE>
|
|
|
|
</LI>
|
|
<LI><B>Q</B>:
|
|
I'm running an older kernel. Where do I get patches?
|
|
<BLOCKQUOTE>
|
|
<B>A</B>:
|
|
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
|
|
<A HREF="http://luthien.nuclecu.unam.mx/~miguel/raid">http://luthien.nuclecu.unam.mx/~miguel/raid</A>.
|
|
See also the quasi-mirror
|
|
<A HREF="ftp://linux.kernel.org/pub/linux/daemons/raid/">ftp://linux.kernel.org/pub/linux/daemons/raid/</A>
|
|
for patches, tools and other goodies.
|
|
</BLOCKQUOTE>
|
|
|
|
</LI>
|
|
<LI><B>Q</B>:
|
|
Are there other Linux RAID references?
|
|
<BLOCKQUOTE>
|
|
<B>A</B>:
|
|
<UL>
|
|
<LI>Generic RAID overview:
|
|
<A HREF="http://www.dpt.com/uraiddoc.html">http://www.dpt.com/uraiddoc.html</A>.</LI>
|
|
<LI>General Linux RAID options:
|
|
<A HREF="http://linas.org/linux/raid.html">http://linas.org/linux/raid.html</A>.</LI>
|
|
<LI>Latest version of this document:
|
|
<A HREF="http://linas.org/linux/Software-RAID/Software-RAID.html">http://linas.org/linux/Software-RAID/Software-RAID.html</A>.</LI>
|
|
<LI>Linux-RAID mailing list archive:
|
|
<A HREF="http://www.linuxhq.com/lnxlists/">http://www.linuxhq.com/lnxlists/</A>.</LI>
|
|
<LI>Linux Software RAID Home Page:
|
|
<A HREF="http://luthien.nuclecu.unam.mx/~miguel/raid">http://luthien.nuclecu.unam.mx/~miguel/raid</A>.</LI>
|
|
<LI>Linux Software RAID tools:
|
|
<A HREF="ftp://linux.kernel.org/pub/linux/daemons/raid/">ftp://linux.kernel.org/pub/linux/daemons/raid/</A>.</LI>
|
|
<LI>How to setting up linear/stripped Software RAID:
|
|
<A HREF="http://www.ssc.com/lg/issue17/raid.html">http://www.ssc.com/lg/issue17/raid.html</A>.</LI>
|
|
<LI>Bootable RAID mini-HOWTO:
|
|
<A HREF="ftp://ftp.bizsystems.com/pub/raid/bootable-raid">ftp://ftp.bizsystems.com/pub/raid/bootable-raid</A>.</LI>
|
|
<LI>Root RAID HOWTO:
|
|
<A HREF="ftp://ftp.bizsystems.com/pub/raid/Root-RAID-HOWTO">ftp://ftp.bizsystems.com/pub/raid/Root-RAID-HOWTO</A>.</LI>
|
|
<LI>Linux RAID-Geschichten:
|
|
<A HREF="http://www.infodrom.north.de/~joey/Linux/raid/">http://www.infodrom.north.de/~joey/Linux/raid/</A>.</LI>
|
|
</UL>
|
|
</BLOCKQUOTE>
|
|
|
|
</LI>
|
|
<LI><B>Q</B>:
|
|
Who do I blame for this document?
|
|
<BLOCKQUOTE>
|
|
<B>A</B>:
|
|
Linas Vepstas slapped this thing together.
|
|
However, most of the information,
|
|
and some of the words were supplied by
|
|
<UL>
|
|
<LI>Bradley Ward Allen
|
|
<
|
|
<A HREF="mailto:ulmo@Q.Net">ulmo@Q.Net</A>></LI>
|
|
<LI>Luca Berra
|
|
<
|
|
<A HREF="mailto:bluca@comedia.it">bluca@comedia.it</A>></LI>
|
|
<LI>Brian Candler
|
|
<
|
|
<A HREF="mailto:B.Candler@pobox.com">B.Candler@pobox.com</A>></LI>
|
|
<LI>Bohumil Chalupa
|
|
<
|
|
<A HREF="mailto:bochal@apollo.karlov.mff.cuni.cz">bochal@apollo.karlov.mff.cuni.cz</A>></LI>
|
|
<LI>Rob Hagopian
|
|
<
|
|
<A HREF="mailto:hagopiar@vu.union.edu">hagopiar@vu.union.edu</A>></LI>
|
|
<LI>Anton Hristozov
|
|
<
|
|
<A HREF="mailto:anton@intransco.com">anton@intransco.com</A>></LI>
|
|
<LI>Miguel de Icaza
|
|
<
|
|
<A HREF="mailto:miguel@luthien.nuclecu.unam.mx">miguel@luthien.nuclecu.unam.mx</A>> </LI>
|
|
<LI>Marco Meloni
|
|
<
|
|
<A HREF="mailto:tonno@stud.unipg.it">tonno@stud.unipg.it</A>></LI>
|
|
<LI>Ingo Molnar
|
|
<
|
|
<A HREF="mailto:mingo@pc7537.hil.siemens.at">mingo@pc7537.hil.siemens.at</A>></LI>
|
|
<LI>Alvin Oga
|
|
<
|
|
<A HREF="mailto:alvin@planet.fef.com">alvin@planet.fef.com</A>></LI>
|
|
<LI>Gadi Oxman
|
|
<
|
|
<A HREF="mailto:gadio@netvision.net.il">gadio@netvision.net.il</A>></LI>
|
|
<LI>Vaughan Pratt
|
|
<
|
|
<A HREF="mailto:pratt@cs.Stanford.EDU">pratt@cs.Stanford.EDU</A>></LI>
|
|
<LI>Steven A. Reisman
|
|
<
|
|
<A HREF="mailto:sar@pressenter.com">sar@pressenter.com</A>></LI>
|
|
<LI>Michael Robinton
|
|
<
|
|
<A HREF="mailto:michael@bzs.org">michael@bzs.org</A>></LI>
|
|
<LI>Martin Schulze
|
|
<
|
|
<A HREF="mailto:joey@finlandia.infodrom.north.de">joey@finlandia.infodrom.north.de</A>></LI>
|
|
<LI>Geoff Thompson
|
|
<
|
|
<A HREF="mailto:geofft@cs.waikato.ac.nz">geofft@cs.waikato.ac.nz</A>></LI>
|
|
<LI>Edward Welbon
|
|
<
|
|
<A HREF="mailto:welbon@bga.com">welbon@bga.com</A>></LI>
|
|
<LI>Rod Wilkens
|
|
<
|
|
<A HREF="mailto:rwilkens@border.net">rwilkens@border.net</A>></LI>
|
|
<LI>Johan Wiltink
|
|
<
|
|
<A HREF="mailto:j.m.wiltink@pi.net">j.m.wiltink@pi.net</A>></LI>
|
|
<LI>Leonard N. Zubkoff
|
|
<
|
|
<A HREF="mailto:lnz@dandelion.com">lnz@dandelion.com</A>></LI>
|
|
<LI>Marc ZYNGIER
|
|
<
|
|
<A HREF="mailto:zyngier@ufr-info-p7.ibp.fr">zyngier@ufr-info-p7.ibp.fr</A>></LI>
|
|
</UL>
|
|
|
|
<P><B>Copyrights</B>
|
|
<UL>
|
|
<LI>Copyright (C) 1994-96 Marc ZYNGIER</LI>
|
|
<LI>Copyright (C) 1997 Gadi Oxman, Ingo Molnar, Miguel de Icaza</LI>
|
|
<LI>Copyright (C) 1997, 1998 Linas Vepstas</LI>
|
|
<LI>By copyright law, additional copyrights are implicitly held
|
|
by the contributors listed above.</LI>
|
|
</UL>
|
|
<P>Thanks all for being there!
|
|
</BLOCKQUOTE>
|
|
</LI>
|
|
</OL>
|
|
<HR>
|
|
<A HREF="Software-RAID-0.4x-HOWTO-2.html">Next</A>
|
|
Previous
|
|
<A HREF="Software-RAID-0.4x-HOWTO.html#toc1">Contents</A>
|
|
</BODY>
|
|
</HTML>
|