67 lines
4.6 KiB
HTML
67 lines
4.6 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.21">
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<TITLE>The Linux Networking Overview HOWTO: Enterprise Linux Networking</TITLE>
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<LINK HREF="Networking-Overview-HOWTO-11.html" REL=next>
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<LINK HREF="Networking-Overview-HOWTO-9.html" REL=previous>
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<LINK HREF="Networking-Overview-HOWTO.html#toc10" REL=contents>
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<BODY>
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<A HREF="Networking-Overview-HOWTO-11.html">Next</A>
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<A HREF="Networking-Overview-HOWTO-9.html">Previous</A>
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<A HREF="Networking-Overview-HOWTO.html#toc10">Contents</A>
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<HR>
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<H2><A NAME="s10">10.</A> <A HREF="Networking-Overview-HOWTO.html#toc10">Enterprise Linux Networking</A></H2>
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<P>In certain situations it is necessary for the networking infrastructure to have proper mechanisms to guarantee network availability nearly 100% of the time. Some related techniques are described in the following sections. Most of the following material can be found at the excellent Linas website:
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<A HREF="http://linas.org/linux/index.html">http://linas.org/linux/index.html</A> and in the
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<A HREF="http://metalab.unc.edu/pub/Linux/ALPHA/linux-ha/High-Availability-HOWTO.html">Linux High-Availability HOWTO</A></P>
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<H2><A NAME="ss10.1">10.1</A> <A HREF="Networking-Overview-HOWTO.html#toc10.1">High Availability </A>
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</H2>
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<P>Redundancy is used to prevent the overall IT system from having single points of failure. A server with only one network card or a single SCSI disk has two single points of failure. The objective is to mask unplanned outages from users in a manner that lets users continue to work quickly. High availability software is a set of scripts and tools that automatically monitor and detect failures, taking the appropriate steps to restore normal operation and to notifying system administrators.</P>
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<H2><A NAME="ss10.2">10.2</A> <A HREF="Networking-Overview-HOWTO.html#toc10.2">RAID</A>
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</H2>
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<P>RAID, short for Redundant Array of Inexpensive Disks, is a method whereby information is spread across several disks, using techniques such as disk striping (RAID Level 0) and disk mirroring (RAID level 1) to achieve redundancy, lower latency and/or higher bandwidth for reading and/or writing, and recoverability from hard-disk crashes. Over six different types of RAID configurations have been defined. There are three types of RAID solution options available to Linux users: software RAID, outboard DASD boxes, and RAID disk controllers.</P>
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<P>
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<UL>
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<LI>Software RAID: Pure software RAID implements the various RAID levels in the kernel disk (block device) code. </LI>
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<LI>Outboard DASD Solutions: DASD (Direct Access Storage Device) are separate boxes that come with their own power supply, provide a cabinet/chassis for holding the hard drives, and appear to Linux as just another SCSI device. In many ways, these offer the most robust RAID solution.</LI>
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<LI>RAID Disk Controllers: Disk Controllers are adapter cards that plug into the ISA/EISA/PCI bus. Just like regular disk controller cards, a cable attaches them to the disk drives. Unlike regular disk controllers, the RAID controllers will implement RAID on the card itself, performing all necessary operations to provide various RAID levels.</LI>
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</UL>
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</P>
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<P>Related HOWTOs:
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<UL>
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<LI>
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<A HREF="http://metalab.unc.edu/mdw/HOWTO/mini/DPT-Hardware-RAID.html">http://metalab.unc.edu/mdw/HOWTO/mini/DPT-Hardware-RAID.html</A></LI>
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<LI>
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<A HREF="http://metalab.unc.edu/mdw/HOWTO/Root-RAID-HOWTO.html">http://metalab.unc.edu/mdw/HOWTO/Root-RAID-HOWTO.html</A></LI>
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<LI>
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<A HREF="http://metalab.unc.edu/mdw/HOWTO/Software-RAID-HOWTO.html">http://metalab.unc.edu/mdw/HOWTO/Software-RAID-HOWTO.html</A></LI>
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</UL>
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</P>
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<P>RAID at linas.org:
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<UL>
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<LI>
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<A HREF="http://linas.org/linux/raid.html">http://linas.org/linux/raid.html</A></LI>
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</UL>
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</P>
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<H2><A NAME="ss10.3">10.3</A> <A HREF="Networking-Overview-HOWTO.html#toc10.3">Redundant networking</A>
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</H2>
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<P>IP Address Takeover (IPAT). When a network adapter card fails, its IP address should be taken by a working network card in the same node or in another node. MAC Address Takeover: when an IP takeover occurs, it should be made sure that all the nodes in the network update their ARP caches (the mapping between IP and MAC addresses). </P>
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<P>See the High-Availability HOWTO for more details:
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<A HREF="http://metalab.unc.edu/pub/Linux/ALPHA/linux-ha/High-Availability-HOWTO.html">http://metalab.unc.edu/pub/Linux/ALPHA/linux-ha/High-Availability-HOWTO.html</A></P>
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<HR>
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<A HREF="Networking-Overview-HOWTO-11.html">Next</A>
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<A HREF="Networking-Overview-HOWTO-9.html">Previous</A>
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<A HREF="Networking-Overview-HOWTO.html#toc10">Contents</A>
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