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Hard Drives Made for RAID Use

Posted by CowboyNeal on from the little-spinny-different dept.

An anonymous reader writes "Hard drive giant Western Digital recently released a very interesting product, hard drives designed to work in a RAID. The Caviar RE SATA 320 GB is an enterprise level drive without native command queueing and uses an SATA interface. In works better in RAID than other drives because of features like its time-limited error recovery and 32-bit CRC error checking, so it is an option when previously only SCSI drives would be considered."

9 of 201 comments (clear)

  1. Typo! by Anonymous Coward · · Score: 3, Informative

    "In works better in RAID..."

    You should change "In" to "It"

    Thank you very much.

  2. SATA version may be new, but features are not new by ptbarnett · · Score: 4, Informative
    Western Digital has been selling an EIDE version with this feature set for a while:

    http://www.wdc.com/en/products/Products.asp?DriveI D=92

    I bought one to replace what I thought was a bad drive in a RAID configuration about a year ago.

  3. TechReport by JohnnyBigodes · · Score: 4, Informative

    Proper TechReport's review here.

    Go read. Now!

  4. Re:Slashdot: Stories Made For Ad Use by ptbarnett · · Score: 4, Informative
    Is that newegg just not having correct data or is there something special about these drives (or are they designed to be "used" less)?

    It's not an error by NewEgg. Follow the link to the manufacturer's site, and you'll see the same specification:

    http://www.wdc.com/en/products/Products.asp?DriveI D=114

  5. Re:Slashdot: Stories Made For Ad Use by cperciva · · Score: 5, Informative

    On the newegg link they list the MTBF as 1 million hours. Google tells me that that is about 114 years. How can it have such high mtbf?

    MTBF is defined as [short time period] * [number of drives tested] / [number of drives which failed within that time period]. An MTBF of 114 years doesn't mean that half of the drives will survive for 114 years without a failure; it means that if you run 114 drives for a year, you should expect to have 1 failure.

    A more intuitive way of conveying the same information is to say that the drives have an expected failure rate of no more than 1E-6 per hour.

    --
    Tarsnap: Online backups for the truly paranoid
  6. Re:Slashdot: Stories Made For Ad Use by Rasta+Prefect · · Score: 5, Informative
    On the newegg link they list the MTBF as 1 million hours. Google tells me that that is about 114 years. How can it have such high mtbf? Is that newegg just not having correct data or is there something special about these drives (or are they designed to be "used" less)?

    Easy: You, like most people, don't know what MTBF means. MTBF is only meaningful in context with the expected lifespan of the device. This is probably somewhere in the neighborhood of 5 years, or about 43,800 hours. Essentially, what the manufacturer is saying is "Based on some data, we estimate that if you run x number of these drives, the average time between failures will be 1,000,000/x hours, up until the expected lifespan of the drive, at which point all bets are off"

    For computer hardware this is always some sort of extrapolated estimate, since they have of course not actually been testing the drive for it's expected lifespan, or it would be obsolete by the time they released it.

    --
    Why?
  7. Re:About time by Ilgaz · · Score: 3, Informative

    Well, serial attached scsi started to ship

    http://www.adaptec.com/sas/index.html?source=home_ story1a_SAS_technology_home

    Pro level already moving but I suspect it will be OK for home with enterprise features it offers.

    I checked a bit you know ;)

  8. Buffalo TeraStation by chocolatetrumpet · · Score: 4, Informative

    Buffalo TeraStation

    Supports RAID 5.

    I emailed if external USB hard drives could be added and swapped to a raid 5 array, and if it can be done "on the fly"...

    but all I got was this lousy message:

    "Please call (800) 456-9799 x. 2013 between 8:30 and 5:30 CT and our presales guys will be able to assist you."

    I'm one of those weird people that would rather communicate in writing. Oh well - no sale.

    --
    Spoon not. Fork, or fork not. There is no spoon.
  9. synchronized spindles? by adrianmonk · · Score: 3, Informative

    I would think if these drives are really designed for RAID (like other drives have been in the past), then they would have support for synchronized spindles.

    The idea behind synchronized spindles is that in order to read data from a disk, you have to wait for the platter to come around part of a revolution for your data to become available, just like picking up your suitcase on the luggage carousel at the airport. How long you need to wait is a matter of luck, because the disk can be assumed to be in a random position when you decide you want your data. When you have RAID without synchronized spindles and you want data that's bigger than the stripe width (or when you're writing and need to update the parity), you have to wait for multiple disks, and they will tend to be spread out so that you tend to wait longer than if you were just waiting for one. With synchronized spindles, as soon as the whole group hits the right position, you've got what you're looking for, and you're done.

    So, the point is, not having synchronized spindles tends to increase average access time, so having synchronized spindles is a desirable feature for a drive designed specifically for RAID.