Why is my RAID HD just as slow as my non-RAID HD?

Discussion in 'Mac Accessories' started by icrude, Dec 30, 2014.

  1. icrude macrumors regular

    Joined:
    Dec 29, 2006
    #1
    Ran the blackmagic test on a WD 6TB RAID HD and was writing 60MB/s and 40MB/s reading. That is almost identical to my WD 2TB non-RAID HD, both running over FW800. Am I missing something here?
     
  2. bennibeef macrumors 6502

    Joined:
    May 22, 2013
    #2
    What RAID number are you using? 0,1,5,6?

    Or did you mean with "a" WD 6TB RAID HD it you really meant one drive and it was labeled as a RAID-ready drive? Well then you got no raid. You can only use RAID with >1 drives.
     
  3. icrude thread starter macrumors regular

    Joined:
    Dec 29, 2006
    #3
    Well it's a 6tb enclosure with 2 drives in it and it's showing up as one big 6tb drive so I'm guessing it's 2 3tb drives raid?
     
  4. ColdCase, Dec 30, 2014
    Last edited: Dec 30, 2014

    ColdCase macrumors 68030

    Joined:
    Feb 10, 2008
    Location:
    NH
    #4
    It could be two 6 TB drives in mirror (RAID1)... but I doubt it. It could also be two drive concatenated instead of RAID0. What does the enclosure manual indicate?

    Perhaps your connection is the bottleneck. Are you sure you are running FW 800 speeds? Open the "about this mac" and system report. Check the speeds to those drives..

    BTW, I have a single fast 7200 RMP drive that performs the same or better than two slow 4200 rpm green drives in a RAID0.
     
  5. matreya, Dec 30, 2014
    Last edited: Dec 30, 2014

    matreya macrumors 65816

    matreya

    Joined:
    Nov 14, 2009
    #5
    Yes, you're using FW800 for a start. If you want fast drives, you'll need to upgrade your Mac and use Thunderbolt.

    You won't get faster speeds over FW800 than 60 MB/sec.
     
  6. ssmed macrumors 6502

    ssmed

    Joined:
    Sep 28, 2009
    Location:
    UK
    #6
    Are you using the Apple thunderbolt/firewire adaptor, this seems slower than natively plugging in FW. I think FW is likely to be your problem, but the speeds you report seem quite slow even so. USB3 would be better if available.
     
  7. paulrbeers macrumors 68040

    Joined:
    Dec 17, 2009
    #7
    That's max speed for FW800. Theoretical max for FW800 is 100MB/s but it's really only about 60MB/s in real life.
     
  8. mmomega macrumors demi-god

    mmomega

    Joined:
    Dec 30, 2009
    Location:
    DFW, TX
    #8
    Exactly what paul and others described.
    Your limiting factor is FW800 at this point.

    You could have a RAID0 with 4 SSD's that are capable of 2,000MB/s but you are limited to whatever connection you use.

    FW400 = 50MB/s
    USB 2 = 60MB/s
    FW800 = 97MB/s
    Gigabit Ethernet = 125MB/s
    USB 3 = 640MB/s
    Thunderbolt = 1250MB/s
    Thunderbolt 2 = 2500MB/s

    These are all max theoretical speeds you could achieve. Usually you will see about 15% less than max, maybe a little more maybe less but that gives you a good idea of what you should be seeing using one of those connection speeds.

    Also to keep in mind is the enclosure and RAID type on the other end of the connection. A single HDD is only capable of roughly 125MB/s.
    So even if you're connecting with USB 3 which can transfer 640MB/s your limiting factor is now your HDD.
    If you RAID0,6,10 your drives you're looking at potentially doubling your transfer speed. So 2 HDD = 250MB/s, 3 drives = 750MB/s and so on.
    Again you won't always achieve this max but it gives you an idea of where you should be.
     
  9. MCAsan macrumors 601

    MCAsan

    Joined:
    Jul 9, 2012
    Location:
    Atlanta
    #9
    As indicated, until you get to transport speeds in the TB1 range, you may not benefit from a specific type of drives ( SSD vs HDD) or a specific configuration of the drives (RAID 0, RAID 1, JBOD).
     
  10. poiihy macrumors 68020

    poiihy

    Joined:
    Aug 22, 2014
    #10
    I have a 2 TB WD Green that gets ~100MB/s :rolleyes:
     
  11. paulrbeers macrumors 68040

    Joined:
    Dec 17, 2009
    #11
    I'm not sure what this post is even about. He simply stated he has two slow drives in RAID 0 that perform slower than a 7200rpm drive. Many new 7200rpms can get something like 180MB/s which easily could beat two of your drives in RAID 0....

    :rolleyes:
     
  12. poiihy macrumors 68020

    poiihy

    Joined:
    Aug 22, 2014
    #12
    What :eek:

    I must be in the past with 320 and 500GB drives at 60MB/s :confused:
     
  13. paulrbeers macrumors 68040

    Joined:
    Dec 17, 2009
    #13
    You don't even understand do you? The OP pointed out it is connected to firewire800 for which (like all your usb 2.0 posts) is a slow interface and 60MB/s is the max the OP will get. I would have thought you would understand this but then again....
     
  14. poiihy macrumors 68020

    poiihy

    Joined:
    Aug 22, 2014
    #14
    I'm talking about internal SATA drives. My 500GB in MBP is about 60MB/s. 320GB in iMac is about the same.
     
  15. paulrbeers macrumors 68040

    Joined:
    Dec 17, 2009
    #15
    What the heck?!?! are you drunk? Would you go back and read all of your posts?!?! You first talked about your Green drive and how that was 100MB/s which had no bearing on this thread. Then you made some comment about old drives, which again had NOTHING to do with this thread, and now you are talking about some internal 500GB drive in your MBP and a 320GB drive in your iMac which AGAIN has NO bearing on a thread about an external drive hooked to a FW800 port.

    Seriously, I'm going to assume English is not your first language or else you have a serious reading comprehension problem (and judging from previous threads you have started that this is a serious issue for you)....
     
  16. poiihy macrumors 68020

    poiihy

    Joined:
    Aug 22, 2014
    #16
    No I thought you were talking about my hard drives were external FireWire drives limited at 60MB/s.

    My first post was a comment to "BTW, I have a single fast 7200 RMP drive that performs the same or better than two slow 4200 rpm green drives in a RAID0." You replied to that and caused an off-topic discussion.
     

Share This Page