My hard drive speed has dramatically decreased!?

Discussion in 'Mac Pro' started by MegaMillions, Jul 7, 2009.

  1. MegaMillions macrumors regular

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    Feb 1, 2009
    #1
    A couple weeks ago when I did an xbench test, my startup disk got around 110.

    Now I get around 80.

    Results for Sequential Write 4K blocks is now around 45 mb/sec instead of around 70 mb, and almost every result has a similar change in speed.

    The only thing I can think of that's different in the computer is an additional 4GB of ram.. but I don't see how that could have anything to do with this.

    I don't notice a difference in computer performance.

    edit: I also just noticed, to my astonishment, that my startup disc now has 40GB more free space than it did a week or two ago. I did not delete 40GB of data. !?!?!
     
  2. Tesselator macrumors 601

    Tesselator

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    #2
    Common causes:

    • Over-heating. Just once for a few minutes can kill an HDDs performance for the rest of it's life. Solution: Replace the drive ASAP.

    • Current temperature. HDDs can and usually do, run slower the higher the temps get. If it got 100 MB/s at 27C it's quite possible that it would only get 70 MB/s at say, something like 45C. Solution: smcFanControl.

    • Data occupancy. As an HDD or RAID becomes increasingly full it also becomes increasingly slow. An HDD at 30% full that gets 100 MB/s in all probability would only get 70 MB/s when 70% full. Solution: Offload some data to another drive or back-up unit.

    Also check the S.M.A.R.T. to make sure it's operating within it's limits. S.M.A.R.T. data gets completely reset periodically (weekly maybe?) so you have to check and recheck 2 or 3 times within about 24~48hrs or something to really tell what's going on.
     
  3. MegaMillions thread starter macrumors regular

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    #3
    What about the 40GB of extra free space, but no data missing? Does that have an explanation?

    It's a 500GB drive and there is 150GB available, and it isn't running over 30 C right now.... so, is the speed pretty much killed for good?

    I guess it's time to get that 1TB Western Digital Caviar Black.
     
  4. zmttoxics macrumors 65816

    zmttoxics

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    May 20, 2008
    #4
    What model of computer is this? If you could have the ram in the wrong configuration causing the speed decrease. The 40GB free could have come from temp files that were removed when you rebooted to install the new ram.
     
  5. MegaMillions thread starter macrumors regular

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    #5
    August 2006 3.0Ghz Quad Mac Pro. For two and a half years i've had 2x 512mb ram in slots 1 and 2 riser A, and 2x 512mb on slots 1 and 2 riser B. Yesterday I installed 2 x 2GB on slots 3 and 4 of riser A. The ram is operating perfectly.
     
  6. bearcatrp macrumors 68000

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    #6
    You should put the larger sticks towards the mother board. Would suggest you run the test after a reboot, then run it again after its been running for awhile. You will see a difference, not real big though.
     
  7. MegaMillions thread starter macrumors regular

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    #7
    So, riser A slots 1 and 2 should be the 2GB chips? And then riser B slots 1 and 2 would be 2 512s, and Riser A slots 3 and 4 would be the other 2 512s?

    Should I try without the 2GB chips at all once, just to see if maybe they cause the problem?
     
  8. zmttoxics macrumors 65816

    zmttoxics

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    #8
    Ya, you did it wrong. According to the manual, it is supposed to be 2 to top tray, then next 2 to bottom tray. http://manuals.info.apple.com/en_US/Mac_Pro_User_Guide.pdf

    This is important for dual channel / smp cpu setups (which you have).
     
  9. MegaMillions thread starter macrumors regular

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    #9
    That's how I did it. There were 2 512 chips on each riser, and the next two I added, I added to the top riser....
     
  10. bearcatrp macrumors 68000

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    #10
    Yep. From what i have read, the sticks closest to the mobo will fill first. Thats why apple states to fill the front ones first before filling the back ones.
     
  11. MegaMillions thread starter macrumors regular

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    #11
    The "front ones" are slots 1 and 2 on each riser, yes? The ones closest to the mobo.
     
  12. zmttoxics macrumors 65816

    zmttoxics

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    #12
    Oops, been a long day. I read that as "in riser A" again.
     
  13. MegaMillions thread starter macrumors regular

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    #13
    Okay so what do I try with the Ram?

    This is what the configuration is now:

    [​IMG]

    edit: o_O, the hard drive speed is back up.... it just got a 108.71 from xbench. The uncached writes are back up to 67 mb/sec, etc.

    I didn't change anything!

    edit 2: on subsequent tests the speeds are now over 70 mb/sec. Totally back to normal.
     
  14. bearcatrp macrumors 68000

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    #14
    Also, i have read that the 512 sticks are slower than the bigger ones. Trying to find the article for you.
     
  15. geoffreak macrumors 68020

    geoffreak

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    #15
    It is a good idea if you keep around 40% of your boot drive free to keep the speed at a maximum.
     
  16. bearcatrp macrumors 68000

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    #16
    Put the 2gb moduals in riser A dimm 1 and 2.

     
  17. MegaMillions thread starter macrumors regular

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    Feb 1, 2009
    #17
    [​IMG]

    Charming. What now?

    edit:

    And after a reboot.....

    [​IMG]

    I'm putting the 2GB chips back in slots 3 and 4 NOW!

    edit 2:

    Okay Now i'm frustrated. After putting them all back in their original locations, the 2GB chips are still only reading as 1GB.

    [​IMG]

    edit 3: And now.... after another reboot, the computer only reads the 512 chips. *sigh* HELP!

    edit 4: I've taken out the 2GB chips. Should I get them replaced? Why did they only start doing this after I attempted to move them?
     
  18. geoffreak macrumors 68020

    geoffreak

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    #18
    Have you tried kicking the computer? Sometimes just yelling at it is enough. If that doesn't work, it at least makes you feel better ;)
     
  19. MegaMillions thread starter macrumors regular

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    Feb 1, 2009
    #19
    Hahaha, no I haven't done that yet.

    OWC will replace them for me. The tech support guy was as baffled as me. I think i'm gonna try putting them in again in slots 3 and 4 riser A, in a few hours.

    He said that it's best to keep the 4x512 as matched pairs one above the other, which is what I thought.
     
  20. Tesselator macrumors 601

    Tesselator

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    #20
    I guess it's either the OS cleaning up, cleaning up belatedly, or just your mistake.

    If that much space on the HDD went belly up then more than likely you would notice some other error conditions. The HDD would lock, the drive wouldn't work at all, the OS would freeze or complain, etc. Also it wouldn't say that space was free and available like you're saying it is.

    But do a surface scan on the drive to be sure. There's one in Disk Utility.app I think.
     
  21. Tesselator macrumors 601

    Tesselator

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    #21
    ??? :confused:

    [​IMG]

    Also i notice lots of finicky-ness about RAM slots and risers in the 2006 ~ 2008 Mac Pros! Sometimes the sensors refuse to work, RAM is improperly identified, RAM is seen at all, etc. etc. Just reseating everything usually helps. I had to reseat the risers 3 times recently to get the thermal sensors to be recognized. Weird stuff! :p
     
  22. MegaMillions thread starter macrumors regular

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    #22
    Wait so, I should put the 2GB chips in slots 1 and 2 of Riser A, and put the 4x512 ALL on riser B? That makes no sense, but that's what that diagram shows.

    Why did it work at all with the 2GB chips in slots 3 and 4 of Riser A, and the 512s in 1 and 2, and 1 and 2, before?
     
  23. hehejames macrumors member

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    NYC
    #23
    Oh my god... Your the dude telling everyone "http://forums.macrumors.com/showthread.php?p=8036273&posted=1#post8036273" Upgrade your RAM on Mac Pro blah blah blah..., but don't seem to be able to follow the instructions or how to properly install your ram. puhahahahha

    Sorry, but you are too funny! :D
     
  24. MegaMillions thread starter macrumors regular

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    #24
    I am a highly experienced mac technician. I've never had a client whose problem I could not solve. Everywhere that I have looked at the directions for installing Mac Pro memory, it has clearly stated, Riser A, 1 and 2, then Riser B, 1 and 2, then Riser A, 3 and 4, then Riser B, 3 and 4. These are the instructions at OWC, and that's what worked perfectly until I tried to move them.

    I know how the computer works, and I know how installing RAM works. In fact, the guy at OWC told me I did it right initially, and that it wasn't a good idea to put the 2GB closer to the motherboard, and split the pairs of 512s from each other. It worked perfectly that way.
     
  25. Tesselator macrumors 601

    Tesselator

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    #25
    ??? :confused:

    That's not what the diagram shows.

    A1, A2, B1, B2 is where your 2GB DIMMs go. (4x2GB) = 8GB

    A3, A4, B3, B4 is where your 512MB DIMMs go. (4x512MB) = 2GB

    You always want the larger DIMMs in the lowest numbered slots.


    PS: I don't think it helps to make people bleed for their mistakes. Gawd if everyone did that to me with all the blunders I've made so far I'd be suicidal and a half. :p
     

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