hardrive and raid question

Discussion in 'Mac Pro' started by macusersince5, Aug 5, 2010.

  1. macusersince5 macrumors member

    macusersince5

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    Mar 13, 2010
    #1
    Ok I have a question about raid and internal mac pro hardrives.

    I have 1 stock mac pro hard drive that has the OS and everything on it. Now I want to purchase three 1.5 tb drives to put in the three empty drive bays of the mac pro. How would I keep my stock hard drive separate from the other three 1.5 hard drives in the system? I want to have the three 1.5 terabyte hard drives act as one big one so I see one partition as 4.5 tb and still see my system drive separate as 650 gb or whatever it was. Can this be done without loosing data or no?
     
  2. Hellhammer Moderator

    Hellhammer

    Staff Member

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    #2
    Yeah, that can be done AFAIK. Just put the new HDs in RAID 0 and they will show as 4.5TB and the 640GB will remain 640GB.
     
  3. macusersince5 thread starter macrumors member

    macusersince5

    Joined:
    Mar 13, 2010
    #3
    ok how to I set that up. I put the three 1.5 tb hardrives in and use the raid utility to set it up and then stick in 650 gb OS hardrive? I am just unfamiliar with how to set this up.
     
  4. spiritlevel macrumors 6502

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    Nov 5, 2007
    #4
    Keep your current hard drive where it is.

    Stick in the new 3 hard drives

    Use Disk Utility to format them into Raid 0

    Job done.

    (Your new drives will have no effect on your current drive)
     
  5. macusersince5 thread starter macrumors member

    macusersince5

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    Mar 13, 2010
  6. VideoFreek macrumors 6502

    VideoFreek

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    #6
    I assume you're aware of the pros and cons of RAID 0? You'll get faster performance, but less reliability. If one disk fails, the entire array is gone and you lose everything! As in any scenario, a solid backup strategy is a must.

    Another option in your case would be RAID 5, much better reliability but at the cost of capacity (approx. 1 disk worth) and performance.

    You have to decide what is more important to you.
     
  7. Vylen macrumors 65816

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    Sydney, Australia
    #7
    On a related note, what (cheap) alternatives are there to Apple's RAID card that provides RAID 5?
     
  8. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #8
    There's multiple cards, and pretty much any other true RAID controller out there is better than the pile of crap Apple RAID Pro card.

    That said, what exactly are you wanting to do (need details in order to help)?

    How many ports?
    How much capacity (not just now, but how much will you need, and when = future expansion)?
    What kind of drives (HDD or SSD)?
    What OS/s?
    What OS is it intended to boot (if at all)?
    What kind of performance do you need (throughputs, or at least detailed specifics for your software usage)?
    Which MP will this be going into (matters, as there will be either extension cable or HDD bay adapters for an internal installation)?
    Or will it all be external (eliminates the need for extension cables and adapters, but now you add in external enclosures and cables)?
    Budget?

    You'd also need to realize at this point, you'd need to be running enterprise grade HDD's if you're going mechanical, and a good UPS (an Online type if at all possible).
     
  9. VideoFreek macrumors 6502

    VideoFreek

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    #9
    Just out of curiosity, am I correct in assuming that your insistence on using a UPS is based on concern about data loss if anything in the cache has not been written out to the array? Doesn't a cache battery take care of this?
     
  10. nanofrog macrumors G4

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    May 6, 2008
    #10
    Yes.

    Both have their limitations (UPS and battery), and ideally, you run both. The UPS's limitation is less time. The battery can last longer (i.e. up to 72hrs or so), but if the file/s are larger than the cache, it's useless to you, as you'll still end up with corrupted file/s (depending on quantity and capacity, as it's possible to have a single file larger than the cache).

    Another thing to consider, is not all RAID card vendors actually offer backup batteries. ATTO for example, is such a company. They claim there's an optional unit, but it's not available anywhere (I've confirmed this over the phone in the past). Their reasoning is the UPS is a better solution, and I agree (instances where only one is possible, whether it's not offered, or budget restrictions; allows the process to be completed prior to the UPS batteries being depleted, so long as it's a sufficiently large enough unit for the tasks the system is used for, assuming the power won't return in time, and there's no backup generator system in place).

    There's no 100% foolproof solution, as even with a backup generator, it can run out of fuel (diesel powered), or the gas lines (natural gas) stop flowing for whatever reason if that's the fuel source.
     
  11. Vylen macrumors 65816

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    #11
    Well, i suppose this is more like research, since I'm planning to get the '10 Mac Pro sooner or later.

    That said, I'm only really interested in RAID 5'ing the internal drives. External ports would be a plus if i ever end up doing that (although I somewhat doubt it). So just one external would do (assuming it supports PM, again, if i ever need it).

    Intending on using HDD's. OS X. Don't think i'll bootcamp windows, but id like to keep that option in the future.

    Don't need blistering fast speeds. Handling RAW photographs. Compiling code. I doubt high speed is need to watch 1080p videos either?

    Budget? No idea - since again.. just research/planning :p But of course, cheapest would be nice.

    I just wish there was software RAID 5 in OS X, cause I'd be content with that haha
     
  12. nanofrog macrumors G4

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    May 6, 2008
    #12
    You'd need an adapter to use internal disks, available at MaxUpgrades (here).

    You can take an internal port externally via the correct cable (SFF-8087 to SFF-8088). The other solution is to use a hybrid card (both internal and external ports; example & price). There are fewer such cards though, and getting an internal port card (2x SFF-8087 ports) would be cheaper, such as the Areca ARC-1222, and use the cable linked (it gets run out of an open PCI bracket, so you'd lose the use of a slot, unless you're willing to cut a hole somewhere on the back of the system).

    Both of these cards can boot OS X (but only OS X or Windows/Linux, not both, as the firmware can only contain EFI or BIOS). But if you install the drivers for another OS, it will still work if the firmware isn't correct to boot it (i.e. boot OS X, but will run under Windows/Linux once the drivers are installed).

    Either of these cards is more than sufficient for what you'll be doing with them from what you've posted (both use the same 1200MHz IOP processor).

    You won't need Boot Camp, as it's just a partition tool (can't share the RAID set with mulitple OS's). You can create multiple arrays on the card however, and go that route (but it won't boot both OS's; see above).

    The way around booting is to use the SATA controller in the system to boot a separate Windows disk (i.e. toss it in the empty optical bay, and attach the cable).

    Please understand, when using a proper hardware RAID card, you'll need to run enterprise grade drives (both of the cards linked are SAS models, but they also run SATA). But if you try to use consumer models, the array won't be stable, even if you do get it to initialize (the recovery timings in consumer models aren't suited for RAID; consumer = 0,0, while enterprise disks = 0,7 - numbers are seconds for read and write respectively). You can't change these values on consumer WD drives any longer (other brands haven't had this option at all).

    No you don't, as software based implementations aren't suited for pairity based arrays (you'll end up with corruption at some point), as it doesn't have an NVRAM solution to the write hole associated with parity based arrays (levels 5 and 6, and carries into nested levels 50 and 60 = 2x parity arrays - 5 or 6 - then stripe both sets together).

    You'll also need to run a good UPS for power protection (preferably an Online type). Batteries exist for some cards, and ideally, is a good thing to have in conjunction with the UPS. But not all cards actually have them available (i.e. ATTO).
     
  13. Vylen macrumors 65816

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    Sydney, Australia
    #13
    Cheers!

    Thanks for all the info. I'll have to bookmark this for later :)
     

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