Best stripe size for two 1TB caviar blacks RAID 0? v

Discussion in 'Mac Pro' started by Wild-Bill, Mar 26, 2010.

  1. Wild-Bill macrumors 68030

    Wild-Bill

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    #1
    Hi. I just got another 1tb drive and I'd like to go raid-0, but I don't know the optimum stripe size
    OS drive is on a seperate hdd ( soon to be ssd ) and the current 1tb houses the user file, movies, etc..
    I just backed up the 1 tb w/ files on it to a new 2 tb wd green.

    Once I establish the RAID-0 on the two 1tb drives, I'll copy over the files to the new array. Not sure if creating the array would wipe out my files, so better safe than sorry.

    Any advice on optimum stripe size? Also, I was curious as to whether or not the array would affect the ability to sleep the drives when not in use.

    Thanks.
     
  2. belvdr macrumors 603

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    #2
    It depends on the size of the files. In general, a 128KB stripe is decent choice.
     
  3. Wild-Bill thread starter macrumors 68030

    Wild-Bill

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    #3
    Well, there are a multitude of sizes actually. In addition to housing my Users folder, I've got movies on there, my iTunes library, Aperture library, basically everything execpt Snow Leopard which is on a second drive.

    So 128k is the best stripe size for this?
     
  4. nanofrog macrumors G4

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    #4
    64k is typically the default, as it gives a balance for both small and large files. If there's more large files, then the larger stripe size will help you, hence the mention of the 128k stripe IMO.

    What we need though, is a good idea of the exact sizes there, and at least an approximation of their % (small vs. large). Without it, we're just guessing.
     
  5. Wild-Bill thread starter macrumors 68030

    Wild-Bill

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    #5
    Thanks for the replies. I'd say its about 50/50 big files to small files ratio. All of my Documents, Downloads, Movies, etc are on it. So I guess I'll go with the 64k stripe size then.

    Also, does anyone know if having a RAID setup on some of your drives will have an effect on the power-saving option to spin down drives when not in use? Or will the array be active at all times?? Just curious.

    As an aside, I ran XBench on my 74 gig Raptor, and a single 1TB Caviar Black. I will be installing my SSD once I create the array and then use SuperDuper to copy the files from the 2TB WD Green to the new array. I'll XBench the array and also xBench the SSD.
    I ordered the ProCaddy2 from TransIntl to properly mount two hard drives in the lower optical bay. I'm going to put a 500 gig in there and the SSD. The main four bays will be the two 1TB array, the 2TB WD Green, and a 750 WD Caviar Black that is devoted to Logic Studio projects. The 500 will be for backing up the files on the 750, and for making a backup of the SSD. I will finally have a proper backup strategy in place. Will probably set the Mac Pro to wake up every Friday in the middle of the night and have the scheduled "smart" backups then.
     
  6. gotzero macrumors 68040

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    #6
    I run 64k on my stripe of two of the 640GB Caviar Blacks. It might be possible to eek out some small bit of better performance, but the array is more than fast enough for what I use it for, so I accepted it and moved on.
     
  7. nanofrog macrumors G4

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    #7
    It seems like 64k is where you want to be then, unless you're access isn't balanced equally.

    Assuming you're using Disk Utility (no mention of a hardware controller), then the OS still has control of the drives, and the power management functions will still work (spin up/down once activity is resumed/timed out).
     
  8. Wild-Bill thread starter macrumors 68030

    Wild-Bill

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    #8
    New SSD woes now........

    Thanks nanofrog and gotzero.

    Here is something that is stumping me now... Rather than create a new thread hopefully I can get some answers from someone....

    Ok, so the Intel SSD is in the lower optical bay, along with a spare 500 gig Seagate. I cannot, for the life of me, get the Intel firmware upgrade ISO disk to recognize the SSD. Says "Intel SSD is not attached or disabled".

    After the first time, I rebooted back in to SL, got the warning that a disk is installed but not initialized (the SSD). So I went ahead and formatted and partitioned it as OSX Journaled. Fine. No problem.
    Now I reboot to the CD-ROM again and the program still can't recognize the SSD. Is this because it's on one of the motherboard SATA slots?? THat's the only thing I can think of. I'd really prefer NOT to dig back into my MP to remove the SSD and hook it up to one of the four internal slots.

    Also, does this firmware even make a difference? Wouldn't having TRIM help it?? Do you think because the drive is blank that it's not recognizing it??

    In the meantime I'm going to SUperDUper my boot drive to it.......

    Thanks again in advance for your replies.
     
  9. Wild-Bill thread starter macrumors 68030

    Wild-Bill

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    #9
    Bump.

    Can anyone help with the post above? ^ ^ ^
    I can't seem to get the Intel ISO to find my SSD to do the firmware upgrade.

    :confused::confused:
     
  10. nanofrog macrumors G4

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    #10
    I'm not quite sure what's going on, but SATA is SATA. The disk is working or you wouldn't have even been able to create the file system on it.

    That said, TRIM is a good idea to have, and the disk being blank wouldn't be the issue. Perhaps the ISO is bad or not compatible with OS X (i.e. Windows & Linux version)?

    Sorry I can't be of more help here. :eek:
     
  11. iMouse macrumors regular

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    #11
    Bad idea, unless...

    WD Caviar Black drives are not designed for RAID. Many have lost data configuring these for RAID due to a function in the drives called Time-Limited Error Recovery.

    You either need to purchase the Caviar RE3 series or look for a utility called WDTLER to enable Time-Limited Error Recovery on the standard Caviar Blacks.

    Beware though. The WDTLER enables/disables TLER on ALL drives connected at one time. I believe the utility is also Win32-only.
     
  12. nanofrog macrumors G4

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    #12
    Consumer drives are fine for software based RAID on a logic board. If it were attached to a proper RAID card, then yes, the REx lines would be appropriate (of WD's offerings).

    That said, enterprise drives are still a good idea, even for software implementation due to their higher reliability IMO, but cost constraints tends to get in the way.
     
  13. VirtualRain macrumors 603

    VirtualRain

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    #13
    I would definitely try connecting it to one of the main drive-bays.
     
  14. gotzero macrumors 68040

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    #14
    On my personal machine, my boot SSDs (Corsair P-Series) are installed in the lower optical bay through the eSATA ports. I have never had an issue with them. Is you machine a 2009? There may be an issue with running through the PCIe bus?
     
  15. nanofrog macrumors G4

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    #15
    It's an '08, and OS X can use HDD's or SSD's attached to the ODD_SATA ports (Windows or Linux cannot; it's an unfortunate issue in the '08 systems). I'm not quite sure if they're capable of loading firmware from them though, and VirtualRain may be correct that the HDD bay is the simple solution for updating the firmware. Once flashed, the drive can be relocated back to the ODD_SATA port. :)
     
  16. gotzero macrumors 68040

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    #16
    Mine is a 2008 too. I do not have much experience with the Intel drives, but I have heard of some issues with 2009 MPs and SATA drives going through the card bus. Worth a check. :)
     
  17. nanofrog macrumors G4

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    #17
    Wild-Bill didn't indicate that any of the drives are attached via a PCIe card though. :confused:

    But moving the SSD to an HDD bay may do the trick (at least to flash the firmware, and move it back to the ODD bay and ODD_SATA port). Worth a shot anyway. ;)
     
  18. Wild-Bill thread starter macrumors 68030

    Wild-Bill

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    #18
    No, no PCIe cards at the moment.

    I will try plugging the SSD into one of the regular bays and see if that will update the firmware for me. Thanks.
     
  19. nanofrog macrumors G4

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    #19
    For some reason, you might want to try bay #2 (I seem to recall something on that port working).

    At any rate, Good Luck, and let us know how it goes. :)
     

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