Raid with this set up..

Discussion in 'macOS' started by ayeying, Mar 17, 2009.

  1. ayeying macrumors 601

    ayeying

    Joined:
    Dec 5, 2007
    Location:
    Yay Area, CA
    #1
    Okay, I don't know much about RAID but since I have 2x500GB drives in this, I want to try it.

    This is what I want:

    Drive 1 - 500GB
    - P1 (500GB)
    Drive 2 - 500GB
    - P2 (250GB)
    - P3 (250GB)

    Drive 1 has 1 partition, 500GB in size.
    Drive 2 has 2 partitions, 250GB per in size.

    I want to set up a RAID 0, software based, between Drive 1 w/ P1 and Drive 2 but with only P2 not including P3.

    Would this work or is the RAID set up exclusive to the drive itself and I cannot partition stuff?

    I want to set up 500+250 GB for OSX and the rest for Boot Camp.
     
  2. jonbravo77 macrumors 6502a

    jonbravo77

    Joined:
    Feb 20, 2008
    Location:
    Phoenix, AZ
    #2
    I don't think you can set up a raid with a non-partitioned drive and a partitioned drive. I believe the drives have to be equal disk space. You may want to take a look at this to get further understanding on Raid's... As it will explain in the link setting up a Raid 0 is fine for increased storage and speed but if 1 disk fails all the data is lost. I to am not well versed in Raids
     
  3. ayeying thread starter macrumors 601

    ayeying

    Joined:
    Dec 5, 2007
    Location:
    Yay Area, CA
    #3
    Anyone else wanna take a stab at the answer?

    I know how a RAID works... I'm just not sure if this set up is even possible. Both drives would be the same speed (5400RPM) and same size (500GB).

    I understand the risks along with RAID-0 also. I'm willing to take that risk, provided i have back ups of my system regularly.
     
  4. michaelwithe21 macrumors member

    michaelwithe21

    Joined:
    Mar 17, 2009
    Location:
    CA
    #4
    Help me help u

    I already posted this somewhere els, but it might help your situation... seeing as I know it works =P

    I'm quite new to the OS (Level) Raid concept provided by the Disk Utility within Leopard OS X 10.5.6 and other OS X OS's, but I saw a great video http://cnettv.cnet.com/2001-1_53-50004485.html showing 2 USB External HD's hooked up to a macbook running a raid to tie them together (striped or mirrored). This concept is simple! But heres my situation:

    I have an iMac 22" 2.4 GHz Intel Core 2 Duo, 4 GB 667 MHz DDR2 SDRAM, Running off of a "298.1 GB WDC WD3200AAJS-40VWA0 Media Hard Drive". I also have an External Drive "465.8 GB WD 5000AAV External Media".

    What I did: Booted to leopard disk, used disk utility to "Merge" a "STRIPED RAID" from my Local (built in 298 GB) HD with a PARTITION of my External (same size 298) as to not waste any left over space on the External (Only as good as the smallest partition). I used 32K block or whatever was default... Everything went very smoothly!

    QUESTIONS:
    1) Does anyone think this could possibly speed up my system in any aspect?
    2) Or slow down my system in any aspect? (because of the USB 2.0 limiter)
    3) Was it "BAD" that I used a partition instead of the whole External hard drive like the video shows?
    4) Minus the "loosing everything if the OS fails", is it a "BAD" idea to use a "Soft" RAID with the HD that your OS runs off of?
    5) Do you know of any "Speed Tests" that would prove this one way or another?

    I herd that you are required to have at least 3 Drives to have a "STRIPED" RAID... but obviously the OS layer of RAID in OS X allows you to use 2.
    I also understand that if my OS fails, than my data on the External (or the Internal for that matter) may not be recoverable. IM OK WITH THIS.

    **Can Striped Raid With Local And External USB Drive Increase System Speeds?**
     
  5. ayeying thread starter macrumors 601

    ayeying

    Joined:
    Dec 5, 2007
    Location:
    Yay Area, CA
    #5
    1) It only speeds up if both drives are running off of SATA internally. USB 2.0 isn't that fast compared to SATA 3.0GB/s.
    2) It could. I don't know the exact answer to that
    3) My question originally is that, if I were to use a partition instead of the entire drive... actually never mind, I just realized it uses the smaller section of the drive... so what I was trying to create, it would mean I only have a 500GB for RAID and another 500GB wasted instead of 750GB raid w/ 250GB free.
    4) No.
    5) XBench?
     
  6. michaelwithe21 macrumors member

    michaelwithe21

    Joined:
    Mar 17, 2009
    Location:
    CA
    #6
    Thank you ayeying

    ayeying... as far as "My question was originally is that, if I were to use a partition instead of the entire drive... actually never mind, I just realized it uses the smaller section of the drive... so what I was trying to create, it would mean I only have a 500GB for RAID and another 500GB wasted instead of 750GB raid w/250GB free."

    Im probably miss understanding you, so ignore if I am =P: of course you can partition the bigger drive to fit the other (as not to "waist space"), just make sure you "partition" the left over raid slice and you can still use it as a backup or watever... in my case using STRIPED (the other kind I know mirrors so you actually get half sized), I was able to get a total of 595GB STRIPED RAID with a left over Partition (backup) with 167GB... none was waisted, just had to be used as a separate drive is all =)... again, please ignore if I completely missed the point =P

    Here is my XBench Results after my Striped RAID "See above for computer and more info" with a Partitioned USB External.. Unfortunately I did not know about this app until after I made the switch.
    BUT: does anyone see anything in the Disk Test or other that might show Increased or Decreased Speeds caused by the Striped RAID?

    Results 161.76
    System Info
    Xbench Version 1.3
    System Version 10.5.6 (9G55)
    Physical RAM 4096 MB
    Model iMac7,1
    Drive Type iMacHD
    CPU Test 151.47
    GCD Loop 282.25 14.88 Mops/sec
    Floating Point Basic 136.52 3.24 Gflop/sec
    vecLib FFT 112.46 3.71 Gflop/sec
    Floating Point Library 150.42 26.19 Mops/sec
    Thread Test 220.51
    Computation 212.74 4.31 Mops/sec, 4 threads
    Lock Contention 228.87 9.85 Mlocks/sec, 4 threads
    Memory Test 159.64
    System 163.87
    Allocate 239.01 877.74 Kalloc/sec
    Fill 137.51 6685.84 MB/sec
    Copy 145.97 3014.98 MB/sec
    Stream 155.62
    Copy 142.82 2949.84 MB/sec
    Scale 149.84 3095.64 MB/sec
    Add 166.42 3545.11 MB/sec
    Triad 166.14 3554.24 MB/sec
    Quartz Graphics Test 194.67
    Line 177.93 11.85 Klines/sec [50% alpha]
    Rectangle 229.93 68.65 Krects/sec [50% alpha]
    Circle 187.85 15.31 Kcircles/sec [50% alpha]
    Bezier 187.08 4.72 Kbeziers/sec [50% alpha]
    Text 198.13 12.39 Kchars/sec
    OpenGL Graphics Test 182.99
    Spinning Squares 182.99 232.13 frames/sec
    User Interface Test 352.37
    Elements 352.37 1.62 Krefresh/sec
    Disk Test 80.42
    Sequential 76.62
    Uncached Write 89.60 55.01 MB/sec [4K blocks]
    Uncached Write 91.29 51.65 MB/sec [256K blocks]
    Uncached Read 43.90 12.85 MB/sec [4K blocks]
    Uncached Read 136.87 68.79 MB/sec [256K blocks]
    Random 84.62
    Uncached Write 45.11 4.78 MB/sec [4K blocks]
    Uncached Write 159.36 51.02 MB/sec [256K blocks]
    Uncached Read 89.40 0.63 MB/sec [4K blocks]
    Uncached Read 130.86 24.28 MB/sec [256K blocks]

    Anyone See anything in the Disk Test or other that might show Increased or Decreased Speeds caused by the Striped RAID?

    NEW Questions:
    1) Does the OS decide (by speed) which Slice (HD) gets used for Files (or how often)?
    2) Is there any way to see how much of each Slice is using (space or CPU)?
    3) Or any way to "prefer" the Sata HD so as not to cause lag when not needed?
     

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