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Managing RAID on Linux
A person deciding to go with RAID faces a panoply of options and gotchas. Hardware or software? How many controllers? ATA or SCSI (or ataraid)? RAID 1 or RAID 5? Which file system or distribution? 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.com, 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 like nohup mdadm -monitor -mail=paranoidsysadmin@home.com (which, if you haven't guessed, causes the system 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 10 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.
Recommended Readings:- Reliable Linux , by Iaian Campbell, Wiley and Sons, Dec 2001, ISBN: 0471070408. Gives excellent information not only about RAID but on general Linux reliability issues.
- Software RAID in the Linux 2.4 Kernel by Daniel Robbins. (Part Two).
- Linux Journal Article on Software RAID by Joe Edwards, Audin Malmin and Ron Shaker. ( Part Two).
- "How to do a gentoo install on software RAID" by Chris Atwood. Gentoo User Forum.
Robert Nagle (aka Idiotprogrammer )is a Texas technical writer, trainer and Linux aficionado. You can purchase Managing RAID on Linux from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
Ask him into your heart today!
although personally I prefer spraying it on my weed. That shit gets your SO FAHKED UP!!! (Esp. Flying Insects RAID!)
In designing a combatives program, there are many discerning factors that must be taken into considera- tion. The first-ever Special Forces Combatives Course that will be discussed in this article is designed for a special breed of soldier. A Special Forces soldier is the most elite fighting man in the United States Army, and possibly the world. He is trained in all areas of combat: communications, demolitions, light weaponry, medical, and intelligence. All SF members are airborne qualified, with many specializing in HALO (High Altitude, Low Opening), SCUBA, STABO (extraction methods), and SERE (Survival, Evasion, Resistance, Escape).
The Special Forces uses unconventional warfare. The very mention of the name brings visions of Vietnam and John Wayne. The Green Beret symbolizes all that America stands for: truth, strength, and pride in being American. Special Forces teams have high-priority missions, sometimes going weeks or months without contact with friendly units. The Special Forces Combatives Course enhances the physical at- tributes, mental awareness, and self-confidence of the SF soldier. Also, due to the type of missions he is assigned, a thorough knowledge of combatives is often necessary to raise the Special Forces soldier's capabilities to a level whereby he will be successful. The Special Forces Combatives Course provides the medium to build a better fighting man, both physically and mentally.
The SF combatives training program furnishes comprehensive physical development, cardiovascular and aerobic conditioning, and develops anaerobic endurance, muscular strength, flexibility and agility. A combination of these physiological factors develops a soldier who is in overall top physical condition-a requirement for the Special Forces mission.
In the Special Forces Combatives Course, Green Berets receive training in the Filipino arts of kali, escrima and arnis. While the Filipino arts emphasize weapons training-especially sticks and bladed weapons-the techniques are also applicable to empty hand fighting.
From a psychological standpoint, the Special Forces Combatives Course is also quite beneficial. The inner knowledge that, if stripped of all weapons, one still has the skills necessary to effectively defend oneself, greatly increases a soldier's self-confidence. Special combatives training, above that of the average soldier, enhances a Green Beret's self-identity and pride in what Special Forces stands for.
The nature of the Special Forces mission means an increased possibility for close-combat encounters. Special Forces combatives training is designed specifically for close combat and is geared for total annihilation. A soldier untrained for close combat might become wounded and/or die in such a situation and thus fail in his mission. A soldier who is properly trained in close combat will effectively neutralize his enemy and accomplish his mission.
The Special Forces Combatives Course is divided into nine basic components: physical fitness, sentry neutralization, Filipino martial arts, kicking, punching and hand strikes, grappling and throwing, knife techniques, equipment training, and mental/philosophical training.
Physical Fitness
A Special Forces soldier must have outstanding endurance, strength, and skill. He must be able to overcome obstacles, kill or disable the enemy in hand-to-hand combat with or without a weapon, and advance swiftly, silently, and effectively. The Special Forces devotes a great deal of time and effort toward making its fighting men the best in the world.
The physical fitness program for the Special Forces Combatives Course is geared toward achieving high fitness levels in the shortest time possible through strenuous physical exercises. This program is divided into five "gates" or stations: upper body, middle body, lower body, reaching, and aerobics. These stations are further subdivided into variables. The variables are based on data drawn from tests and studies conducted over a number of years, as well as personal experiences of the instructors. The exercises include conventional Army programs, tai chi reaches, Ranger push-ups, Tiger push-ups, martial arts stretching, isometric resistance, SCUBA sit-ups, and boxing reachbacks.
Sentry Neutralization
Sentry neutralization is taught utilizing empty-hand, garrote, and knife techniques. Not only are the actual killing movements taught and practiced, but also the philosophy of close-quarter termination, stealth, stalking, visual domination, spring power, timing, environmental control, and spontaneous reactions (both of yourself and the sentry target). Realism in all situations is stressed to its highest point. Two-man sentry neutralization techniques are presented for absolute control of an armed guard.
The problem is the spam. Very few people want to have their cyber identity tied to their email address in such a direct fashion.
.name zone has about 10,000 Web pages in it. So you can work out the number of domains they have probably sold.
.name domains should not be too worried however. The same thing happened to .tv which spent through its initial VC funding at record pace and was bought out for about a tenth of the amount spent on building the brand. Someone will buy .name, although bidding is not likely to be brisk.
The
The big problem that the new registries face is that they thought that starting a new domain was a license to print money for doing nothing. They simply did not expect that there might be some actual work involved.
$35 sounds a lot by geek consumer standards, but you need a minimum of 2,000 names to cover the cost of hiring one person at that price - including salary, overhead, benefits etc. You need a minimum of 5 people to provide round the clock support.
The business models of the new domains expected people to buy millions of them in the first year. They did not understand that maybe it might take five years to build a critical mass.
It is always easier to look at someone elses business, particularly a successful one and decide that it is essentialy easy to run and cost free than to have your own idea. Look at all the folk who blundered into etail thinking that the economics of that space would somehow be different to the economics of mail order, a business notorious for its low margins and high infrastructure costs. Or look at the folk who blundered into home delivery of groceries, an even lower margin business, building $30 million distribution centers to serve markets that could not possibly support the interest payments, let alone register a profit.
Folk who have
TROLL! You are so full of shit it's not even funny. Please try again.
"To hell with your heathen feather and to hell with your cowardly counsel," Pere Callahan said. He stepped into the aisle and began to hobble down the center aisle, stepping with the grim gait of arthritis. He wasn't as old as the Manni elder, nor nearly so old as Tian's gran-pere (who claimed he was the oldest person not only here but in Calla Lockwood to the south), and yet he seemed somehow older than both. Older than the ages. Some of this no doubt had to do with the haunted eyes that looked out at the world from below the scar on his foreheard (according to Zalia, it had been self-inflicted). More had to do with the sound of him. Although he had been here long and long--enough years to build his strange Man Jesus church and convert half the Calla to his way of spiritual thinking--not even a stranger would have been fooled into believing Pere Callahan was from here. His alienness was in his flat and nasal speech and in the often obscure slang he used ('street-jive," he called it). He had undoubtedly come from one of those other worlds the Manni were always babbling about, although he never spoke of it and Calla Bryn Sturgis was now his home. He had been here since long before Tian Jaffords was born--since town elders like Wayne Overholser and Vaughn Eisenhart had worn short pants--and no one disputed his right to speak, with or without the feather.
Younger than Tian's gran-pere he might be, but Pere Callahan was still the Old Fella.
4
Now he surveyed the men of Call Bryn Sturgis, not even glancing at George Telford. The feather sagged in Telford's hand. He sat down on the first bench, still holding it.
Callahan began with one of his slang-terms, but they were farmers and no one needed to ask for an explanation.
"This is chickenshit."
He surveyed them longer. Most would not return his look. After a moment, even Eisenhart and Adams dropped their eyes. Overholser kept his head up, but under the Old Fella's dry and bitter gaze, the rancher looked petulant rather than defiant.
"Chickenshit," the man in the black coat and turned-around collar repeated. A small gold cross gleamed below the notch in the backwards collar. On his forehead, that other cross--the one he'd supposedly carved in his flesh with his own thumbnail in partial penance for some awful sin--glared under the lamps like a tattoo.
"This young man isn't one of my flock, but he's right, and I think you all know it. You know it in your hearts. Even you, Mr. Overholser. And you, George Telford."
"Know no such thing," Telford said, but his voice was weak and stripped of its former persuasive charm.
"All your lies will cross your eyes, that's what my mother would have told you." Callahan offered Telford a thin smile Tian wouldn't have wanted it pointed in his direction. And then Callahan did turn to him. "I never heard it put better than you put it tonight, boy. Thankee-sai."
Tian raised a feeble hand and managed an even more feeble smile. He felt like a character in a silly festival play, saved at the last moment by some improbable supernatural intervention.
"I know a bit about cowardice," Callahan said, turning to the men on the benches. "I have personal experience, you might say. I know how one cowardly decision leads to another...and another...and another...until it's too late to turn around, too late to change. Mr. Telford, I assure you the tree of which young Mr. Jaffords spoke is not make-believe. The Calla is in dire danger. Your souls are in danger."
"Hail Mary, full of grace," said someone on the left side of the room, "the Lord is with thee. Blessed is the fruit of thy womb, J--"
"Bag it," Callahan snapped. "Save it for Sunday." His eyes, blue sparks in their deep hollows, studied them. "For this night, never mind God and Mary and the Man Jesus. Never mind the sneetches and light-sticks of the Wolves, either. You must fight. You're the men of the Calla, are you not? Then act like men. Stop behaving like dogs crawling on their bellies to lick the boots of a cruel master."
Overholser went dark red at that, and began to stand. Diego Adams grabbed his arm and spoke in his ear. For a moment Overholser remained as he was, frozen in a kind of crouch, and then he sat back down. Adams stood up.
"Sounds good, padrone," Adams said in his heavy accent. "Sounds brave. Yet there are still a few questions, mayhap. Haycox asked one of em. How can ranchers and farmers stand against armed killers out of the west?"
"By hiring armed killers of our own," Callahan replied.
There was a moment of utter, amazed silence. It was almost as if the Old Fella had lapsed into another language. At last Diego Adams said--cautiously, "I don't understand."
"Of course you don't," the Old Fella said. "So listen and gain wisdom. Rancher Adams and all of you, listen and gain wisdom. Not six days' ride northeast of us, and bound southwest along the Path of the Beam, come three gunslingers and one 'prentice." He smiled at their amazement--their utter and complete amazement. Then he turned to Tian. "The 'prentice isn't much older than your Heddon and Hedda, but he's already as quick as a snake and as deadly as a scorpion. The others are quicker and deadlier by far. You want hard calibers? They're at hand. I set my watch and warrant on it."
This time Overholser made it all the way to his feet. His face burned as if with a fever. His great pod of a belly trembled. "What children's goodnight story is this?" he asked. "If there ever were such men, they passed out of existence with Gilead. And Gilead has been dust in the wind for a thousand years."
There were no mutterings of support or dispute. No mutterings of any kind. The crowd was still frozen, caught in the reverberation of that one mythic word: gunslingers.
"You're wrong," Callahan said, "but we don't need to fight over it. We can go and see for ourselves. A small party will do, I think. Jaffords here...myself...and what about you, Overholser? Want to come?"
"There ain't no gunslingers!" Overholser roared.
Behind him, Jorge Estrada stood up. "Pere Callahan, God's grace on you--"
"--and you, Jorge."
"--but even if there were gunslingers, how could three stand against forty or sixty? And not forty or sixty normal men, but forty or sixty Wolves?"
"Hear him, he speaks sense!" Eben Took, the storekeeper's son, called out.
"And why would they fight for us?" Estrada continued. "We make it from year to year, but not much more. What could we offer them, beyond a few hot meals? And what man agrees to die for his dinner?"
"Hear him, hear him!" Telford, Overholser, and Eisenhart cried in unison. Others stamped rhythmically up and down on the boards.
The Old Fella waited until the stomping had quit, and then said: "I have books in the Rectory. Half a dozen."
Although most of them knew this, the thought of books--all that paper--still provoked a general sigh of wonder.
"According to one of them, gunslingers were forbidden to take reward. Supposedly because they descend from the line of Arthur Eld."
"The Eld! The Eld!" the Manni whispered, and several raised fists into the air with the first and fourth fingers raised. Hook em horns, the Old Fella thought. Go, Texas. He managed to stifle a laugh, but not the smile that rose on his lips.
"Are ye speaking of hardcases who wander the land, doing good deeds?" Telford asked in a gently mocking voice. "Surely you're too old for such tales, Pere."
"Not hardcases," Callahan said patiently, "gunslingers."
"How do you know, Pere?" Tian heard himself ask. "And how can three men stand against the Wolves?"
One of the gunslingers was actually a woman, but Callahan saw no need to muddy the waters further (although an impish part of him wanted to, just the same). "I know because I know," he said. "As for how three may stand against many--three and an apprentice, actually--that's a question for their dinh. We'll ask him. And they wouldn't be fighting just for their dinners, you know. Not at all."
"What else, then?" Bucky Javier asked.
Callahan knew they were there because he had seen them. He had seen them because the thing under the church floor had awakened. They would want the thing under the floor, and that was good because the Old Fella, who had once run from a town called Jerusalem's Lot in another world, wanted to be rid of it. If he wasn't rid of it soon, it would kill him.
Ka had come to Calla Bryn Sturgis. Ka like a wind.
"In time, Mr. Javier," Callahan said. "All in good time, sai."
Meantime, a whisper had begun in the Gathering Hall. It slipped along the benches like from mouth to mouth, a breeze of hope and fear.
Gunslingers.
Gunslingers to the east, come out of Mid-World.
And it was true, God help them. Arthur Eld's last deadly children, moving toward Calla Bryn Sturgis along the Path of the Beam. Ka like a wind.
"Time to be men," Pere Callahan told them. Beneath the scar on his forehead, his eyes burned like lamps. Yet his tone was not without compassion. "Time to stand up, gentlemen. Time to stand and be true."
Yeah! Wanna make somethin' of it?
Modest doubt is called the beacon of the wise. - William Shakespeare