Managing RAID on Linux

Features

• Cover Type: Paperback with 260 pages
• Published by: O'Reilly Media, Inc. December 2002
• Written in: English
• ISBN 10 Number: 1565927303
• ISBN 13 Number: 978-1565927308
• Book Dimensions: 9.1 x 7 x 0.7 inches
• Weighs: 15.5 ounces

Product Description
Redundant Array of Independent Disks (RAID) technology is becoming a standard feature of computer systems that support mission-critical services like file sharing, mail exchange, or Web servers. RAID offers two benefits to these essential systems: improved I/O performance and fail-safe data storage. Although bandwidth problems on networks are well documented, the internal data transfer bottleneck that exists at the hardware level in each system can also leave you with perplexing performance issues. RAID is a cost-effective and easy-to-manage way to alleviate this bandwidth problem by distributing the I/O load seamlessly across multiple disks and controllers. RAID also provides uninterrupted data access through disk mirroring and parity algorithms. That means systems can remain online even during a disk or controller failure. RAID is scalable, making it robust enough for large, high-traffic sites and small, critical systems. By using RAID, system administrators can combine single disks into terabytes worth of data storage. Managing RAID on Linux covers everything system administrators need to know to put together a system that can support RAID. You will learn about the different types of RAID, along with associated technologies and issues, and how to choose the best RAID system for your needs. With a step-by-step, hands-on approach, the author guides you through the installation of either Linux software RAID or a hardware RAID card. The book shows how to build an array and optionally install a high-performance file system. Contents include:

• An introduction to RAID and Linux
• Planning and architecture of your RAID system
• Building a software RAID
• Software RAID tools and references
• Building a hardware RAID
• Performance and tuning of your RAID system

RAID has become the low-cost solution of choice to deal with the ever-increasing demand for data storage space. Written for system administrators, power users, tech managers, and anyone who wants to learn about RAID technology, Managing RAID on Linux sidesteps the often-confusing vendor-specific approach you'll find elsewhere to give you the straight story on RAID. Even non-Linux users will find this book full of valuable material.

About The Author
lives in New York City. He works for azurance.com, an open source and security consulting firm that he co-founded. He has been published in SysAdmin Magazine, Linux Journal, The Perl Journal, and The Journal of Linux Technology.

Reader Reviews
The availability of HOW-TOs and newsgroups is supposed to make the sysadmin's job easier, right? Much as I am a proponent of the 'distributed learning model' for Linux, the endless searching for answers on the Web for setting up Linux RAID was getting to be a royal pain. Sure, there was a RAID how-to and an excellent newgroup, but some of the information is out of date, and the tricks suggested by people a year ago may be no longer needed today. A person deciding to go with RAID faces a panoply of options and gotchas. Hardware or software? How many controllers? ATA or CSI (or ataraid)? RAID 1 or RAID 5? Which file system or disstribution? Kernel options? Mdadm or raidtools? /swap or /boot on raid? Hybrid? Left or right symmetric? One poster pointed out that putting two ATA drives on the same controller could impact performance. Yikes! Didn't I do that? Upon discovering that O'Reilly had just published its Managing RAID on Linux book, looking at sample chapter , I bought the book and let my blood pressure return to normal. RAID is one of these subjects that is really not complex; it's just very hard to find all the information in one place. This is precisely the book to solve the problem. Author Derek Vadala, sysadmin and founder of Azurance, an open source/security consulting firm, has gathered a lot of information and even personal anecdotes to go through the decision making process when going over to RAID. He goes step-by-step through that process, educating us about hard drives, controllers, and bottlenecks along the way. This exhaustive book may be the first to bring RAID to the masses. Although parts of the book (RAID types, file system types) may seem already familiar to experienced Linux users, it is helpful nonetheless to have everything in a nifty little book. A section of file systems provided not only a rundown of the merits and drawbacks of each one, but also a guide to their utilities. I learned for example what "file tails" for Reiser are, and why using them causes performance to degrade after reaching 85% capacity. The book compares raidtools with mdadm as well as lovely commands to email you RAID status reports upon boot). People who use software RAID may skip over the chapter on RAID utilities for the leading RAID controller cards. Still, there was one interesting tidbit: Why, the author asks, do makers of controller cards put all their BIOS utilities on DOS floppies which require us to find a DOS boot disk? Seriously, how many of us carry around DOS boot disks nowadays? The book made me aware for the first time of freedos, an open source solution that solves precisely that problem. The Software RAID stuff was pretty thorough and clarified a lot of things. The book does an excellent job in helping to identify and eliminate bottlenecks and optimizing hard drive performance (using hdparm and various monitoring commands). The anecdotes and case studies definitely clarified which RAID solution is suited for which task. I am less impressed by the book's sections on disaster recovery and troubleshooting. Although these subjects are brought up at several places in the software RAID chapter, the book could have discussed several failure scenarios or used a fault tree (such as the famous Fault Tree in Chapter 9 of the Samba book, a marvel for any tech writer to read). The book doesn't even discuss booting with software RAID until the last ten page of the book and then gives it only a single paragraph (even though the author acknowledges it as "one of the most frequently asked questions on the linux-raid mailing list."). Call me old-fashioned, but isn't the ability to boot into your RAID system ... kinda important? As someone who just spent a significant amount of time troubleshooting RAID booting problems in Gentoo, I for one would have liked more insight into the grub/lilo thing. Also, in the next paragraph in the last chapter on page 228, the author casually mentions that "all /boot and / partitions must be on a RAID-1." Say what? Please pity the poor newbie who religiously follows the instructions in the book but fails to read until the end. I'm not sure what the author meant by this statement, but it required a much more substantial explanation and needed to go into a much earlier chapter. These complaints don't detract very much from this excellent book, a true O'Reilly classic and a model of clarity and helpfulness. This book provides enough knowledge to avoid the dread and uncertainty that comes with trying to tackle Linux RAID. With a book like this, a sysadmin can sleep a little easier. Comment | | (Report this)