http:// www.cio.com/article/print/499671

From multicore to many-core to hard-to-describe-in-a-single-word core
But Kunle Olukotun, then a newly minted professor of electrical engineering at Stanford, saw that the party couldn’t go on forever. The microprocessors of the day couldn’t scale up as efficiently as you’d expect through the mere addition of ever more and ever faster transistors, the two things that Moore’s Law provided

http://spectrum.ieee.org/semiconductors/processors/multicore-cpus-processor-proliferation/0

This document is intended to help Linux and Internet users who are learning by doing. While this is a great way to acquire specific skills, sometimes it leaves peculiar gaps in one’s knowledge of the basics ? gaps which can make it hard to think creatively or troubleshoot effectively, from lack of a good mental model of what is really going on.

I’ll try to describe in clear, simple language how it all works. The presentation will be tuned for people using Unix or Linux on PC-class machines. Nevertheless, I’ll usually refer simply to ?Unix? here, as most of what I will describe is constant across different machines and across Unix variants.

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Particularly for hard disks, the tool in charge is smartctl from the package smartmontools. IDE disks (if they?re not of the age of dinosaurs) have an integrated self-testing tool called SMART which means ?Self-Monitoring, Analysis and Reporting Technology?. Modern SCSI disks have it too if they?re SCSI 3 or newer. It happens that inside the disk chipset there are routines to check parameters of disk health: spin-up time, number of read failures, temperature, life elapsed? And all of those parameters are not only registered by the disk chipset, but they have designated security limits and both parameters and limits can be checked by software who access the disk using the appropriate I/O instructions.

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There’s a good chance the most powerful chip inside your PC, in raw computational terms, is on your graphics card. So, how did graphics get so powerful, what are graphics cards good for right now and how on earth do you choose from the baffling array of 3D chipsets on offer?

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As with every other component, motherboards have come a long way from the original IBM PC of 1981. If you’re old enough to remember the first De Lorean DMC-12, perhaps the original PC XT mobo still casts some dark shadow over your memory? At the time there were certainly wonders to behold; these days, they simply look a mess with integration the last thing on the designers mind and all the IO having to be decidedly off-board.

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Want to get an idea of what speed advantage adding an expensive hardware RAID card to your new server is likely to give you? You can benchmark the performance difference between running a RAID using the Linux kernel software RAID and a hardware RAID card. My own tests of the two alternatives yielded some interesting results.

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Everybody who owns a computer will someday need to dispose of a disk drive. Before you do, it is a good idea to cleanse the drive, so no one can read your sensitive information. Deleting files and reformatting is not sufficient; determined effort can still reveal data from a drive even after it appears to be gone. To do a more thorough job, I suggest using wipe.

You need to take special pains because files that are “deleted” are not really gone. Most operating systems, including Linux and its ext2 filesystem, just delete the pointer to a deleted file; the data still exists on the drive. It is not effectively removed until every bit of the space it was occupying on the drive has been overwritten. Even then there are ways, albeit difficult, to analyze the drive and extract data. The only way, short of melting the drive, to ensure the data is gone for good is to overwrite the drive several times with random data.

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The storage capacity and data retrieval speeds of Hard Disks have increased multiple folds in last few years. However for large business organizations, which not only need to store terabytes of invaluable data but access them frequently as well. These organizations cannot afford to let their systems go offline even for a short duration of time. Moreover they cannot even think of loosing even small amount of data due to disk failure or for that matter any other reason.

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It’s a given that all disks eventually die, and it’s easy to see why. The platters in a modern disk drive rotate more than a hundred times per second, maintaining submicron tolerances between the disk heads and the magnetic media that store data. Often they run 24/7 in dusty, overheated environments, thrashing on heavily loaded or poorly managed machines. So, it’s not surprising that experienced users are all too familiar with the symptoms of a dying disk. Strange things start happening. Inscrutable kernel error messages cover the console and then the system becomes unstable and locks up. Often, entire days are lost repeating recent work, re-installing the OS and trying to recover data. Even if you have a recent backup, sudden disk failure is a minor catastrophe.
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External hard drives aren’t as fast as internal models, but they are great for backups and are easy to install. Ratings and rankings can change due to pricing and technology changes, so check back frequently for the latest info.

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Need more storage? The top-ranked internal hard drives will fill the bill. Ratings and rankings can change due to pricing and technology changes, so check back frequently for the latest info.

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