Starting to piece together my next machine...

Discussion in 'OT Technology' started by deusexaethera, Feb 3, 2008.

  1. deusexaethera

    deusexaethera OT Supporter

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    ...in my imagination, anyway. I want to wait to see whether AMD can pull the microcode they gave to the BIOS companies out of the shitter before I make a move, but assuming they get things sorted, I'll be going with a Phenom 4-core setup. (Maybe an Opteron 4-core, if/when they hit the market.)

    My question isn't about the CPU, though, but about the RAID controller. Now that I've got one machine with a RAID, it's pretty much a given that I'll keep equipping my main machines with them henceforth. So here's one that caught my eye, it has a good rating and a decent price, and I want to find out if anyone has any opinions about it and/or other suggestions that deliver more bang:buck.

    [​IMG]
     
  2. redfred18t

    redfred18t New Member

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    just wondering, what are the benefits of having raid? from what I've read (just a snippet) , it seems that if you have one HD fail, you're focked.
     
  3. Doc Brown

    Doc Brown Don't make me make you my hobby

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    Only on RAID 0, because it's not redundant.

    I'm mostly in the same boat as you, since I haven't ran a RAID.
    But also, from what I understand, if you use a shitty controller you can run into more trouble if a drive fails.

    Hence the $300+ range of what Deus is looking at.
     
  4. deusexaethera

    deusexaethera OT Supporter

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    No, that's what happens if you don't run a RAID. Doc and Jolly are right about RAID0 -- it splits data between all the drives, but it doesn't store backup data to reconstruct a drive if it dies, so you lose everything on all the drives at once. That's what you're thinking of, and I tried that once and learned my lesson.

    A real RAID uses one or two drives to store backup data (actually called "parity") that's calculated based on the files you put on the array. If any one drive (or two drives, if you opted for that kind of setup) dies, the calculations are reversed and the missing data is reconstructed. The only real RAID that doesn't work like this is RAID1; RAID1 just stores two identical copies of everything instead.

    - - -

    Oh, Doc, if you want a cheap yet effective RAID controller, Newegg is still selling the PNY S-Cure controllers using the NetCell processors for something like 30 bucks. If I didn't already own two, I'd be tempted to buy another.
     
  5. Doc Brown

    Doc Brown Don't make me make you my hobby

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    I would be interested for sure. Especially with a $30 controller.
    Only problem for me is that RAID has to be installed during the operating installation, no?

    I've got my Acronis backup tweaked really good, and I would hate to have to start all over so that I could run RAID.
     
  6. deusexaethera

    deusexaethera OT Supporter

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    The NetCell-based controller emulates an IDE channel, so Windows thinks it's talking to an IDE disk. It does this without special drivers, too, which is a plus. I moved my stuff to the RAID using Norton Ghost, and since the card doesn't need any drivers to work right, it just picked up where it left off.

    On my father's audio rig, I actually installed the RAID controller first, then plugged in a single disk, then cloned his existing drive to the single-disk RAID. After that was done, I shut down and added the two extra disks to the RAID controller, booted up again, and told it to expand the single-disk RAID to include all three disks. The NetCell's one downfall is that it took a couple of days (yes, days) for it to expand the RAID, but it worked nonetheless, and doing it that way saved me having to swipe one of my Firewire external drives from my office for the weekend.
     
  7. deusexaethera

    deusexaethera OT Supporter

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    Okay, I've found the hot-swap bay I'm going to use, too.

    [​IMG]

    No, your eyes don't deceive you. Those are four 2.5" bays, packed into a single 5.25" bay. Why would I do this? Because as nice as my Raptors are, they are huge power hogs, and if SATA2 laptop drives are good enough for use in "Enterprise Solutions" (i.e. big fucking servers), then they're good enough for any desktop machine I'm going to build. This thing will let me have my RAID and probably cut the wattage of my machine by 1/3 in the process.

    The only question is: do I get one, or two? :naughty:
     
    Last edited: Feb 4, 2008
  8. Gob

    Gob Illusion, Michael. A trick is something a whore do OT Supporter

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    I'm sort of in the same boat as Doc Brown. I've never set up a RAID, but that S-Cure card in the 30 buck range makes it tempting to try out. I hope you don't mind a couple of newbie questions.
    Do all the drives need to be identical? I have two 750gb Seagate drives and a 400gb Seagate.
    Is there a performance increase or is it just a redundancy thing?
    All the drives are spinning when data is accessed correct? So its possible that the power supply may need to be upgraded?
     
  9. Doc Brown

    Doc Brown Don't make me make you my hobby

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    That does look sweet, no doubt. But what about cooling on that?
     
  10. Doc Brown

    Doc Brown Don't make me make you my hobby

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    I thought it was only 15 watts per drive, but I'm seeing number around 35 on google. Either way, it's not very much to add two drives.

    I asked a ton of questions about RAID on another thread about it, and if I recall, you can mix different drives.
    But if the size is different then the larger drive is limited to the amount the smaller drive can hold.

    Of course I probably don't have that right either.

    :mamoru:
     
  11. deusexaethera

    deusexaethera OT Supporter

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    1. The disks don't have to be identical; however, it's recommended for two reasons:

    1a. The data is split evenly between the disks, meaning that each disk will only hold as much data as the smallest disk in the array.

    1b. Identical disks will behave predictably compared to each other, which makes it easier for the RAID controller to tell when one has failed; using mismatched disks makes it more likely that the RAID controller will mistake a slower-responding disk for a failed disk, which isn't the end of the world, but it is annoying when you have to rebuild the array over and over for no good reason.

    2. It's done for both performance and redundancy. The RAID "level" you choose depends on your priorities:

    RAID0: Splits the data between all drives (called "striping"),but has no redundancy, which increases speed because no processing is required, but if one drive dies all the data is lost because there's no way to reconstruct the missing pieces.

    RAID1: Maintains two identical copies of all data all the time, so if one copy gets trashed, the other copy keeps working. The two copies allow for 2x the read speed, but the write speed is the same as a single disk.

    RAID3: The same as RAID0, except an extra disk is used to store "parity" data that can be used to reconstruct data from any one disk that dies. Read speed increases according to the number of disks, write speed is usually limited to the speed of a single disk because the parity has to be recalculated and it all has to go on the one parity disk.

    RAID5: Same as RAID3, except the parity data is distributed across all the drives in a round-robin pattern. This eliminates the bottleneck when writing data, because the parity doesn't all have to go onto a single disk, but read speed is somewhat slower than RAID3 because each disk has to skip over the parity data that is meaningless to the user.

    RAID6: Same as RAID5, except the amount of parity data is doubled, so two disks can fail at once without the world coming to an end.

    RAID10: A combination of RAID0 and RAID1, in that two identical RAID0's are maintained, to allow for very high read/write speed and no loss of speed if one of the RAID0's fails, but it requires buying 2x as many disks as you really want. Only suitable where cost is no object.

    3. Yes, all disks have to be spinning at the same time. If you've already got all those disks plugged in, then your power supply is already good enough.
     
  12. Doc Brown

    Doc Brown Don't make me make you my hobby

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    I'll be a sumbitch. I had that right.

    :eek3:
     
  13. deusexaethera

    deusexaethera OT Supporter

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    It has a fan that blows out the front of the cage -- or if it doesn't blow out, I'm sure it can be flipped around with minimal effort. In any event, laptop drives almost never get any cooling at all, so any that get plugged into a cage like this are getting spoiled and have nothing to complain about.
     
  14. Doc Brown

    Doc Brown Don't make me make you my hobby

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    Can you do a RAID 1 but with 3 drives for extra redundancy?
     
  15. deusexaethera

    deusexaethera OT Supporter

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    Probably. I can't imagine anyone except banks and tanks would have a setup like that though.
     
  16. Doc Brown

    Doc Brown Don't make me make you my hobby

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    Ok, another question then. If I setup a normal RAID 1 with two discs,
    would I be able to access those drives via a third drive, with a normal drag and drop procedure?

    edit*

    And by that I mean, copying files from the RAID array onto a third drive?
     
  17. deusexaethera

    deusexaethera OT Supporter

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    Yes, you can copy files to/from the array. It wouldn't be much use if you couldn't do that.

    And since we're talking about a RAID1 here, you could delete the RAID array altogether and still be able to copy files off one of the disks, since each disk in a RAID1 maintains a full, identical copy of everything. That wouldn't work on any other kind of RAID, though.
     
  18. Doc Brown

    Doc Brown Don't make me make you my hobby

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    Huh. This could be a good thing then. Maybe, lol.

    I mainly want to be able to back up the files onto an external drive that's not plugged in all the time. Less chance of losing everything that way.
     
  19. deusexaethera

    deusexaethera OT Supporter

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    That's what my father's computer does. He has the same RAID3 I have, and I built a Firewire external drive for him to copy his shite onto in case the computer explodes.
     
  20. deusexaethera

    deusexaethera OT Supporter

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    Hmm. I just went and actually looked up some numbers, and my three 75GB Raptors are using 30.05 watts, whereas four Scorpios would use 10.00 watts. I guess that's not dropping my power consumption by a third, but 20W * a few years of near-continuous operation should add up to a nice chunk of electricity not consumed. It will also make cooling the machine easier.
     
  21. Gob

    Gob Illusion, Michael. A trick is something a whore do OT Supporter

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    Thanks for the discussion on RAID cards/setup. Its been very helpful. I'll probably try and pick up another 750gb drive and that card when I get my tax return.

    Another quick question though. It appears as though the S-Cure card manufacturer are no longer in business. In the event that the RAID controller failed (I don't know how likely this is?) would it be possible to simply swap out a newer card and have all the data on the drives remain intact. Or is the process more involved than that?
     
  22. deusexaethera

    deusexaethera OT Supporter

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    Yeah, NetCell's out of business. That's why the cards are so cheap.

    No, you can't replace the card with a different brand without destroying the array and making a new one. (Consider it motivation to keep a backup of your data, which you should do anyway.) Of course, at $30 a pop, you can pick up a spare (which can detect your existing array and let you keep using it), and still be $240 less in the hole than I'll be when I get the card I started the thread with.
     
  23. eideteker

    eideteker Who jarked off in my frakkin' coffee? OT Supporter

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    That 5.25" bay is nice, if you get it let us know how it works out. :wavey:
     
  24. Doc Brown

    Doc Brown Don't make me make you my hobby

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    I looked up that card last night and I see they still have the 5 drive cards for just under $40.
    I notice though, that the card is the Sata 150 spec.

    Then I spotted this Promise controller for $74 that has SATA 3.0
    http://www.newegg.com/Product/Product.aspx?Item=N82E16816102063

    Any thoughts?
     
  25. deusexaethera

    deusexaethera OT Supporter

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    Two thoughts:

    1. The Promise controller you posted has only two ports and only supports RAID0 or RAID1. If you were going to set up a simple two-disk RAID1, it would be enough. Otherwise, it wouldn't be.

    2. SATA1 really isn't much of a restriction; if you plug in five disks into a single card, the slot the card is in will be more restrictive than the individual SATA ports.
     

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