Mac Pro: JBOD or Software RAID

Discussion in 'Mac Pro' started by DSchwartz88, Jul 10, 2010.

  1. DSchwartz88 macrumors 6502

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    May 18, 2006
    #1
    so here is my question/dilemma. I had a server running in RAID0 that had a drive fail so I lost everything. I will be using a large portion of the storage simply to hold media to stream to my TV, so having one large filesystem doesn't give me any benefits.

    Should I just set up the mac pro with every drive having its own share or should i RAID0 my drives?

    Im leaning towards a JBOD solution but someone more experienced may be able to give me a better point of view.
     
  2. WardC macrumors 68030

    WardC

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  3. DSchwartz88 thread starter macrumors 6502

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    #3
    Just a Bunch Of Disks, it means not RAIDing anything and just having every disk be its own independent partition, keeping all the data on the drive itself, no striping or anything.

    for more info: http://en.wikipedia.org/wiki/Non-RAID_drive_architectures
     
  4. WardC macrumors 68030

    WardC

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    #4
    When I get my new Mac Pro I am either doing RAID0, 10,000rpm Velociraptor, or SSD. Something fast for my boot drive. Haven't decided which option I am going yet.
     
  5. strausd macrumors 68030

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    #5
    You may want to do JBOD considering if one drive goes out in a RAID 0 config, you're gonna lose everything. If a drive goes out in JBOD, then you only lose whats on that one drive. Also, make sure you back up!
     
  6. DSchwartz88 thread starter macrumors 6502

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    #6
    Thats exactly what im doing. I have an Intel X25-M 160GB SSD on the way for my boot drive. Gonna throw my home folder on one of the 2TB drives, and then install 3 x 2TB drives (ill do a 4th in the second optical drive if it comes to that) and use that to hold a bunch of media (HD TV, HD Movies etc for Boxee streaming).

    I have a ReadyNAS Duo with 2 x 1TB drives and its already full...
     
  7. Loa macrumors 68000

    Loa

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    #7
    Hello,

    These days, with very cheap 2TB drives, the only reason I can think of for using JBOD is to allow easier file organization for media storage usage. For anything else, JBOD is pretty much useless.

    The solution to your problem is very easy: RAID0 + back-up. If you need to back-up everything you have on a 8TB RAID0 et, that will be costly. But think about this: backing-up everything for a 8TB JBOD will be just as costly.

    RAID0 didn't make you lose data: the fact that you didn't have back-up made you lose data.

    Loa
     
  8. strausd macrumors 68030

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    #8
    True, but restoring an 8TB RAID 0 will take much longer than a single 2TB drive.
     
  9. DSchwartz88 thread starter macrumors 6502

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    May 18, 2006
    #9
    yeah exactly... I dont have the cash to backup 8TB so im willing to take the risk of only losing 2TB rather than all of it. Yeah yeah I know back up, sure I backup my important stuff, but im really gonna spend all that cash just to back up 8TB of media I could download again in a couple days? idk seems stupid to me.
     
  10. jav6454 macrumors P6

    jav6454

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    #10
    Do SSD. Using a mechanical drive @ 10K rpms is asking for problems.
     
  11. Loa macrumors 68000

    Loa

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    #11
    Then RAID0 what you back-up and use single disks for the rest.

    Loa
     
  12. nanofrog macrumors G4

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    May 6, 2008
    #12
    You need a backup system no matter what you've got, but it's even more critical when using a striped set as the primary array. You're begging for trouble like this if you don't.

    You may run into throughput throttling with all of this attached to the internal SATA ports, as the ICH is limited to ~660MB/s (assuming multiple disks will run simultaneously).

    The 80GB SSD can produce ~250MB/s, and a single 2TB disk ~110MB/s (reads in both cases). For 3x mechanical + the SSD, you get 580MB/s, which is fine. It's the addition of the 4th disk that could hurt you, as you're now at 690MB/s.

    To prevent this, you'd need another SATA controller to take some of the load, and push it across the PCIe lanes instead.

    What are you using it for?

    I ask, as you need to do something about this, but the answer (as well as other information), could get you into the right solution. Time may also be of critical importance, depending on the overall storage configuration, or you could be open to a disaster.

    No, it's not useless.

    Let's say the JBOD is used as a backup solution, and a stripe set is used for the primary data location. Now you get a simultaneous failure (both lose a drive). Instead of losing all of the data, you only lose whatever is on the failed disk in the JBOD set.

    Not ideal, but you'd be amazed how many users don't have a primary backup system, let alone more than one (i.e. on-site + off site, or at least archived to tape or optical media, as would be the case with purchased DVD movies for example).

    Downloaded movies tend to fall into this connundrum, and takes both time and money to re-download everything that's lost the user wants back (assuming the sources aren't DRM hacked copies available on torrent sites).

    It's not ideal, but better than a total loss. You'd be best to get an external enclosure (Port Multiplier chip equiped) and an eSATA card for a large capacity backup solution.

    It will save you a lot of time and money, if you're not getting your content off of torrent sites (in which it's only time, if your ISP doesn't have fees for exceeding data caps).

    The Velociraptor is an enterprise grade drive, and mechanical is still better suited to high write environments than SSD's, particularly MLC based models.

    MLC is fine however for an OS/applications disk, as it spends the vast majority of it's life reading rather than writing data.
     
  13. whwang macrumors regular

    Joined:
    Dec 18, 2009
    #13
    660 MB limit

    Hi nanofog,

    Do you mind elaborating more on what you meant by "hurt?"

    I am going to get a MacPro with an SSD in one of the optical bay as the boot drive, and 4 2TB drives (WD RE4) for data and scratch (and of course backup systems). I plan to partition all the 2TB drives into 0.5TB + 1.5TB, and put the 4x0.5TB partitions into RAID0. This way, each of the 0.5TB partition can produce 130-140 MB/s and therefore 500-560 MB/s in RAID0. Now, if the SSD is running at the same time, the disks will saturate the 660MB/s ICH bandwidth. What kind of "hurt" I will get in addition to not being able to go beyond 660MB/s? If there are no other negative drawbacks, I am happy with just having 660MB/s of throughput.
     
  14. nanofrog macrumors G4

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    May 6, 2008
    #14
    The previous values for the disks are sustained, not burst (burst may or may not matter, depending on your usage).

    At any rate, if you try to push 690MB/s through a 660MB/s pipe, you get throttling, which is a bottleneck. More data trying to get through than the ICH can handle (drives stall momentarily if the disk cache is full). The difference here may not be that big a deal in your case, and can be lived with (thinking it can, given your attitude towards it, as you haven't indicated what the usage is).
     
  15. whwang macrumors regular

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    Dec 18, 2009
    #15
    I am using it for some kind of image processing, with frequent read/write of files of roughly 10-100 MB sizes and occasion read/write of GB size files. I think the pattern is pretty similar to photoshop. Do you think saturating the 660MB limit will have significant negative impact?
     
  16. nanofrog macrumors G4

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    May 6, 2008
    #16
    Not really, as Photoshop seems to do fine with ~250MB/s sustained throughputs (since you've used it as a gauge).
     

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