raid????

Discussion in 'OT Technology' started by nicklovgren, Sep 4, 2005.

  1. nicklovgren

    nicklovgren The only thing that really worried me was the ethe

    Joined:
    Jan 19, 2005
    Messages:
    2,232
    Likes Received:
    0
    Location:
    wisconsin
    how hard is raid to set up?
    would i be better off buying a raid card?
    and what is the raid where 2 hds are shared and one is mirroring those two?
    :eek3:
     
  2. Peyomp

    Peyomp New Member

    Joined:
    Jan 11, 2002
    Messages:
    14,017
    Likes Received:
    0
    RAID 0 is striping. You put every other sector of data on alternating (in the case of a 2 disk array) disks. This increases read speeds for large files. But it doubles the risk of data loss through disk failure.

    RAID 1 is when two hard drives mirror one another. In Windows 2K, you do not need to buy a RAID card. In fact, most RAID cards (Promise, etc.) that are targetted at the home are worse than OS Software RAID.

    To setup RAID 1 you go into disk setup... somewhere. You know, I can't explain how to do it... but its under disk properties. You mirror the contents of one drive onto the other, and you're off. Takes a few minutes, but its easy. I suggest you look this up on google.

    The second disk that you add needs to be identical to the first: same part number from same manufacturer.

    To setup other types of RAID cannot be done while the system is up, unless you have an expensive hardware RAID card. Some of those will convert from a single disk to different kinds of arrays on the fly, but they are usually SCSI, and are expensive (few hundred dollars at least).

    The only setup that people actually use that I can think of that you are describing is RAID 5 on three disks. The data is striped across all 3 disks, but you only get the capacity for 2. google://"RAID 5" for cost:benefit analysis. Otherwise there is RAID 10/0+1, where two disks stripe, and two disks mirror. This is a good setup for just about anything, but requires 4 disks.

    If this is for anything but a server application, where you are willing to spend alot of money on a hardware SCSI RAID controller (and one or two expensive SATA controllers, but only the best made)... then forget RAID 5. It does not perform worth a shit on cheap controllers.
     
  3. Yep

    Yep Knick knack paddy whack, give the old dog a bone

    Joined:
    Jan 22, 2001
    Messages:
    4,603
    Likes Received:
    0
    Location:
    South Jersey
    I think my next build will have Raid 0 Raptor's with my extra IDE drives as image storage.
     
  4. Peyomp

    Peyomp New Member

    Joined:
    Jan 11, 2002
    Messages:
    14,017
    Likes Received:
    0
    That will work swell until... you lose one drive, and then all your data is gone. For me, RAID 1 is what I'll use on my home systems. The reads are quicker, and the writes are the same as one disk.
     
  5. nicklovgren

    nicklovgren The only thing that really worried me was the ethe

    Joined:
    Jan 19, 2005
    Messages:
    2,232
    Likes Received:
    0
    Location:
    wisconsin
    i'm thinking of running raid 5 on my next puter.....will i even notice a difference though ya think....i'm running windows xp
     
  6. Yep

    Yep Knick knack paddy whack, give the old dog a bone

    Joined:
    Jan 22, 2001
    Messages:
    4,603
    Likes Received:
    0
    Location:
    South Jersey
    That's why I'll have a second drive dedicated to storing a backup image.

    Even still two 74GB Raptors in RAID 0 still have a better reliability rate than 1 single Maxtor IDE or WD hard drive.
     
  7. Repentinus

    Repentinus New Member

    Joined:
    Aug 13, 2005
    Messages:
    586
    Likes Received:
    0
    Location:
    Lawton, OK
    Actually no it doesn't. By putting two HDs in RAID 0 you double your chance of failure than by having just one HD. That's because you are screwed if EITHER drive fails.
     
  8. deusexaethera

    deusexaethera OT Supporter

    Joined:
    Jan 27, 2005
    Messages:
    19,712
    Likes Received:
    0
    I built my friend a computer with the following setup:

    OS and My Documents: Drive0
    Games, Programs, and Swap File: Drive1 + Drive2 = Raid0

    This setup puts the OS and My Documents out of harm's way, and it allows the computer to access replaceable data (things that can be reinstalled in case of failure) at a much faster speed and gives the Swap File an extra boost of speed as well. He loves it; no complaints since day 1.

    And since the motherboard was designed with RAID0+1 over SATA connections, no RAID card was needed and each drive gets a connection all to itself -- so they don't have to share bandwidth (which would defeat the purpose of RAID entirely).
     
  9. deusexaethera

    deusexaethera OT Supporter

    Joined:
    Jan 27, 2005
    Messages:
    19,712
    Likes Received:
    0
    Exactly. You double the risk because you can't rescue the data on the one remaining disk -- every unit of data has been chopped in half and half of each unit has just been erased. With a Raid1 you cut the risk in half because you have two copies of every single unit of data -- both disks have to die at the same time for the data to disappear.
     
  10. Yep

    Yep Knick knack paddy whack, give the old dog a bone

    Joined:
    Jan 22, 2001
    Messages:
    4,603
    Likes Received:
    0
    Location:
    South Jersey
    The raptors are rated at somewhere around 1.2 million hours of continuous use and have a 5-year warranty, so I'm not too concerned about failure rate.

    I also made mention of the word "imaging", which it seems, everyone is overlooking. Imaging = Zero data loss in a failure.
     
  11. Peyomp

    Peyomp New Member

    Joined:
    Jan 11, 2002
    Messages:
    14,017
    Likes Received:
    0
    But that would require a disk double the size of the individual disks in the 2-disk RAID 0 array, and you would incur alot of overhead by mirroring between dissimilar disks. Whats more, I don't know how many computers you've had, but disk failures long before the expected operating life of the drive are hardly rare.

    It sounds like what you actually want is RAID 10/0+1. 4 disks: 2 mirrored sets of striped disks.
     
    Last edited: Sep 6, 2005
  12. Peyomp

    Peyomp New Member

    Joined:
    Jan 11, 2002
    Messages:
    14,017
    Likes Received:
    0
    Unless you're willing to pay at least several hundred dollars for the top of the line SATA hardware RAID card (there are only a few SATA cards that aren't software based... nevermind what the box says), or a good SCSI RAID card, both of which need a big cache to handle the logic associated with RAID 5 with good performance... then no. Forget RAID 5.

    You can get smaller disks, but get 4 of them, and run a RAID 10 array.
     
  13. Peyomp

    Peyomp New Member

    Joined:
    Jan 11, 2002
    Messages:
    14,017
    Likes Received:
    0
    Another way to increase disk performance is to put your OS directories and your application/media directories on separate disks. Separate partitions helps as well. On a database server, for instance, you would see a RAID 1 array for the OS and applications, and then a separate RAID array (be it 1, 10/0+1, or 5) for the database data.
     

Share This Page