A8V promise controller question: can ide Raid & Sata Raid both be used simultaneously?

Discussion in 'Asus' started by Bucky, Mar 6, 2005.

  1. Bucky

    Bucky Guest

    Hey.

    I have not set up my A8V system yet, and it will be a while I think.
    I was wondering something. There is a parallel Raid connection on the
    board, can it be used at the same time as the Sata Raid of that
    controller?

    In fact, can all three Raid setups be used at the same time, for 6
    total Raid drives?
     
    Bucky, Mar 6, 2005
    #1
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  2. Bucky

    Wayne Fulton Guest


    There are two, the VIA controller and the Promise controller.

    Each disk controller handles four disks (2 SATA, 2 Parallel), and each
    can do RAID (or can do individual drives too). They can both be used.
    I have two RAID disks on the Promise, and one disk and one CD on the VIA

    Each controller is very versitile, many choices and combinations,
    including multiple RAID arrays. I dont know if all eight drives can be
    in one RAID array, but I dont otherwise see how we might have 4 arrays
    with only 4 drives?

    The A8V manual has a section on RAID at section 5-6.
    Also the A8V CD has some manuals on RAID.
     
    Wayne Fulton, Mar 6, 2005
    #2
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  3. Bucky

    Paul Guest

    In theory, you could put four drives on the 20378 and two on the
    Southbridge.

    But the problem is, putting two parallel drives on the 20378 means
    accesses to the two drives can interfere with one another on the IDE
    cable and reduce your performance. If you put four drives on there,
    I would pair a SATA drive with a parallel drive, to make a RAID 0
    or RAID 1. If you do RAID0+1, there might be an advantage to putting a
    SATA+PATA as striped pairs, then mirroring the two pairs against
    one another, but there is still the potential for the IDE cable
    to become a limit. For best performance, I would use no more than
    two drives on the Promise 20378, and either make the drives 2xSATA
    or SATA+PATA, but avoid PATA+PATA. If you don't care about
    performance, any combo will work.

    You can use the Promise 20378 for single drives if you want, and
    there is an ATA driver available if you don't want to RAID. Since
    the Promise doesn't support ATAPI, hard drives are a good thing to
    use with the ATA driver. (That means your CD/DVD ATAPI devices
    go on the Southbridge.)

    Southbridge RAID implementations can sometimes be faster than
    PCI chips, like the Promise 20378, because they may gain access
    to the North-South bus, without going through a bandwidth limiting
    PCI bridge. If you don't currently own the disk drives intended for
    this system, buy 2xSATA and then test them on both interfaces, and
    make your choice that way.

    And, if you are doing a striped array, don't put the boot partition
    on there, because if a stripe breaks, you won't be able to boot.
    RAIDs are just a PITA to maintain, so there better be a good reason
    to use one. If you use the mirror option, for example, you still
    need to do backups (a power supply failure can burn both drives
    and your data would still be lost). Also, a comfirmed RAID addict
    would put a UPS on the computer, so a power failure can never
    desynchronize a mirrored array.

    HTH,
    Paul
     
    Paul, Mar 6, 2005
    #3
  4. Bucky

    Bucky Guest

    Paul, how likely can a striped RAID break, and what about just going
    0+1. I know nothing about RAID really, having never used it. I have
    only used SCSI non RAID. I wanted to put Windows on the RAID for
    maximum speed, as my thinking was that speeding up Windows hard drive
    accesses would speed up my system considerably.

    Paul, could you tell me more about RAID, and/or refer me to a good
    site that tells more.

    I am thinking that, well, if I put my non critical stuff on a mirrored
    array (and yes, I have three UPSs, they just need batteries, but they
    work, APC 620 & 630s that have network connections) and on non RAID
    IDE I would be covered.

    What about JBOD? What is RAID 0, RAID 1, and is RAID 0+1 a
    combination of striping and mirroring in some way?

    Also, what is the story on RAID 5? Does it require 4 hard drives, and
    if so, why didn't Asus build it into the A8V board?

    Also, thank you VERY much for your excellent reply. I appreciate
    everyone's help here.
     
    Bucky, Mar 6, 2005
    #4
  5. Bucky

    Paul Guest

    For a simple two disk stripe, if either of the two drives fails,
    your data is toast. So, that is double the risk of a failure.
    Now, if you think your disks are truly of heroic quality, go right
    ahead and stripe the boot disk.

    A 0+1 will certainly fix most simple media failures (but not
    the "burned by the PSU" type failure). The problem is, most users
    do not experiment with the four disks and learn how to handle a
    failure, so when the chips are down, they don't know which disk(s)
    to grab and replace, and they don't know what buttons in the
    interface are safe to click or not (like, is "delete array" a
    safe button ?). And the manual is just useless at explaining all
    the issues. So, you have four disks in your hands, you know
    something is busted, but you are paralyzed with fear when it
    comes time to fix it.

    I prefer my accidents to be simple ones. Using a single disk for
    my computer, the disk either works, or it is toast. Maintenance
    is simple - do backups, buy a replacement disk if the current
    one breaks. If I want speed, I can buy a single 15K RPM SCSI disk,
    with a >90MB/sec data rate.

    One thing you might do, is visit a web site like Promise or Highpoint
    or the like, and download a manual for a real RAID card. There might
    be more background info in a real RAID card manual, then the five
    pages you get in a mobo manual.
    RAID5 can be done on as few as three drives.

    JBOD stands for Just A Bunch Of Disks.

    0+1 consists of two pairs of disks, each pair is a stripe, and
    the pairs mirror one another. If a single disk fails, one stripe
    breaks, but the pair of disks in the other stripe take over.

    I'm afraid for the rest of your questions, you'll have to hit
    a search engine. Due to my lack of experience, there are better
    sources of info out there than I can provide.

    To find out about fast disks, www.storagereview.com is a good
    place to look. They have a performance database, and they keep
    track of disk speeds, noise and heat. That is where I go, to
    figure out which brand of disk to buy. For general discussions
    about building arrays, the forums at 2cpu.com are a lot of fun.
    The 2cpu people do a lot of server stuff, and that is where
    RAID is a good thing, in a server environment.

    Paul
     
    Paul, Mar 6, 2005
    #5
  6. Bucky

    Paul Guest

    Someone posted this link about Sil0680 in this group. Notice
    how the guy in this thread, does a lot of experiments with
    his RAID array and learns how to use it. Trying all sorts
    of things, before there is valuable data on the array, will
    pay off later. (BTW - the Sil0680 is just about the worst
    controller there is - it is actually not a hardware RAID,
    but relies on firmware/software to make it go. Slow as
    molasses, and the silicon chip is "as old as the hills" :)
    The chip was designed when the company was called CMD, then
    Siimage bought the company, and has been flogging the 0680
    ever since.)

    http://forums.storagereview.net/index.php?showtopic=15712

    Paul
     
    Paul, Mar 6, 2005
    #6
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