Xserve RAID

Discussion in 'Hardware Rumors' started by shadowfax0, Jul 25, 2002.

  1. shadowfax0 macrumors 6502

    Joined:
    May 2, 2002
    #1
    When is this thing coming out? And what were the specs exactly? (Pictures would be nice too :) )
     
  2. job macrumors 68040

    job

    Joined:
    Jan 25, 2002
    Location:
    in transit
    #2
    Ever try to use the "search" function? :)

    That's where I got this pic.

    Thanks to Rower_CPU for posting it earlier.
     

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  3. vitruvius macrumors regular

    Joined:
    Feb 26, 2002
    Location:
    Caracas, Venezuela
    #3
    Xserver design its nicer and cleaner than the RAID, but i guess its not a problem of looks and quality, but more optimisation and Quantity problem
     
  4. mmcneil macrumors regular

    Joined:
    Sep 4, 2001
    Location:
    San Diego, CA
    #4
    Specs?

    The original article was posted under a different thread, however it did not include the spec I am most interested in - the level of RAID supported. Given that it is a hardware controller - I am hoping for level ten.

    What happens when you start with 6 disks, then upgrade to 10? I assume you do a major backup, re-configure, then restore. Anyone know?
     
  5. Rower_CPU Moderator emeritus

    Rower_CPU

    Joined:
    Oct 5, 2001
    Location:
    San Diego, CA
    #5
    Your welcome.;)

    mmcneil-

    Are you referring to 1+0...striping and mirroring? I've never heard of RAID level 10 before...

    I would assume that best practice would be to do what you said.
     
  6. mmcneil macrumors regular

    Joined:
    Sep 4, 2001
    Location:
    San Diego, CA
    #6
    RAID Levels

    According to a recent post and URL -

    Level 5 is the most popular one for big operations. It is more complex. It uses 3 or more drives (often up to 12, and even more). If n is the number of drives, it writes 1/(n-1) of the data to each drive except for one. So if there are 12 drives, it writes 1/11th of the data to each of 11 drives. The last drive is called a "parity drive," and it contains nothing but parity data.

    Level 10 is a lot like 0+1, but it has no limitation on the number of drives. It is a mirror of two big stripes.
     
  7. Rower_CPU Moderator emeritus

    Rower_CPU

    Joined:
    Oct 5, 2001
    Location:
    San Diego, CA
    #7
    Re: RAID Levels

    Interesting..thanks.:)
     
  8. Funkatation macrumors regular

    Joined:
    Dec 29, 2001
    #8
    here's the correct definition of RAID....

    Got it from whatis.com

    "There are at least nine types of RAID plus a non-redundant array (RAID-0):

    * RAID-0. This technique has striping but no redundancy of data. It offers the best performance but no fault-tolerance.
    * RAID-1. This type is also known as disk mirroring and consists of at least two drives that duplicate the storage of data. There is no striping. Read performance is improved since either disk can be read at the same time. Write performance is the same as for single disk storage. RAID-1 provides the best performance and the best fault-tolerance in a multi-user system.
    * RAID-2. This type uses striping across disks with some disks storing error checking and correcting (ECC) information. It has no advantage over RAID-3.
    * RAID-3. This type uses striping and dedicates one drive to storing parity information. The embedded error checking (ECC) information is used to detect errors. Data recovery is accomplished by calculating the exclusive OR (XOR) of the information recorded on the other drives. Since an I/O operation addresses all drives at the same time, RAID-3 cannot overlap I/O. For this reason, RAID-3 is best for single-user systems with long record applications.
    * RAID-4. This type uses large stripes, which means you can read records from any single drive. This allows you to take advantage of overlapped I/O for read operations. Since all write operations have to update the parity drive, no I/O overlapping is possible. RAID-4 offers no advantage over RAID-5.
    * RAID-5. This type includes a rotating parity array, thus addressing the write limitation in RAID-4. Thus, all read and write operations can be overlapped. RAID-5 stores parity information but not redundant data (but parity information can be used to reconstruct data). RAID-5 requires at least three and usually five disks for the array. It's best for multi-user systems in which performance is not critical or which do few write operations.
    * RAID-6. This type is similar to RAID-5 but includes a second parity scheme that is distributed across different drives and thus offers extremely high fault- and drive-failure tolerance. There are few or no commercial examples currently.
    * RAID-7. This type includes a real-time embedded operating system as a controller, caching via a high-speed bus, and other characteristics of a stand-alone computer. One vendor offers this system.
    * RAID-10. This type offers an array of stripes in which each stripe is a RAID-1 array of drives. This offers higher performance than RAID-1 but at much higher cost.
    * RAID-53. This type offers an array of stripes in which each stripe is a RAID-3 array of disks. This offers higher performance than RAID-3 but at much higher cost. "
     
  9. mmcneil macrumors regular

    Joined:
    Sep 4, 2001
    Location:
    San Diego, CA
    #9
    thanks!!

    Hadn't see all the definitions - still like ten for a high performance, high fault-tolerant system. We are looking at an enterprise system a requirement for a high level of reliability and reasonable speed. It will be interesting to actually start comparing the $$ vs performance when we are ready to proceed.
     

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