Previous 1 2 Next 23 Replies Latest reply: May 17, 2009 6:33 AM by antio
mixedmedia Level 1 (0 points)

I have a late 2006 model 20" iMac with 2.16GHz Core 2 Duo, 250GB Western Digital SATA II hard drive and 2.5GB of RAM.

Recently, the hard drive performance had plunged where the spinning ball had started to appear more frequently, applications started to hanged and it seems to take forever to copy large files from an external HDD. I have read similar problems in other topics and tried all the solutions/workaround given but still cant solve the problem I am having:

1. Tried the Disk Utility to Verify/Repair Disk and also Disk Permissions, restarted in the single user mode to execute the /fsck -fy command, restarted in Safe Mode for the disk check, downloaded AppleJack for diagnostics.

2. Initially using Tiger, purchased Leopard just to ensure there's nothing wrong with software, where I have wiped out the hard drive to make a clean install of Leopard. The problem persists, so I tried to reinstall Leopard again, but nothing did changed.

3. Attempted to erase the hard disk with "write zeros" options, but it takes forever to finish, as in 14 days! Yes, I know this is absurd as I had done this before and it only took around 5-7 hours maximum on this 250GB hard drive. So I proceed with only a plain erase as a try. Still no changes.

4. Did a Western Digital Diagnostics test while booting in Windows XP, which went along for around an hour or so, and the BSOD came out. Need to restore to a previous restore point to boot in again.

5. Found a problem of hard disks being in a PIO state instead of Ultra DMA and I have fixed it in Windows, but still no changes. I do not know if you can fix that in OS X?

That is pretty much what I have done and tried to solve this. But still cant figure out any solutions.

And this is the benchmark results I did in Xbench for the disk performance:

Sequential 1.00
Uncached Write 0.52 0.32 MB/sec [4K blocks]
Uncached Write 0.49 0.28 MB/sec [256K blocks]
Uncached Read 55.31 16.19 MB/sec [4K blocks]
Uncached Read 123.67 62.16 MB/sec [256K blocks]
Random 4.16
Uncached Write 19.01 2.01 MB/sec [4K blocks]
Uncached Write 1.14 0.36 MB/sec [256K blocks]
Uncached Read 44.00 0.31 MB/sec [4K blocks]
Uncached Read 139.69 25.92 MB/sec [25

Where the centre number is just the score for each speed achieved. You can clearly see how low is the disk speed.

Could any of you list the possible causes for this and possibly the solution including the advice of replacing the HDD? It seems like my HDD's busted.

Also, I am looking at purchasing a 500GB WD for a replacement.

Thanks in advance.

iMac 20" Late 2006, Mac OS X (10.5.5), 2.16GHz C2D, 250GB HDD, 256MB X1600, 2.5GB RAM
  • Kappy Level 10 (265,951 points)
    Well, running a Windows disk utility on a Mac drive ought to muck things up pretty well. I hope you have backups. If not I suggest you try to backup your files. Then do the following:

    Extended Hard Drive Preparation

    1. Boot from your OS X Installer Disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Installer menu (Utilities menu for Tiger or Leopard.)

    2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Note the SMART status of the drive in DU's status area. If it does not say "Verified" then the drive is failing or has failed and will need replacing. SMART info will not be reported on external drives. Otherwise, click on the Partition tab in the DU main window.

    3. Set the number of partitions from the dropdown menu (use 1 partition unless you wish to make more.) Set the format type to Mac OS Extended (Journaled.) Click on the Options button, set the partition scheme to GUID (only required for Intel Macs) then click on the OK button. Click on the Partition button and wait until the volume(s) mount on the Desktop.

    4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.

    5. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, check the button for Zero Data and click on OK to return to the Erase window.

    6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.

    Upon formatting completing quit DU to return to the installer. Install OS X. Afterwards you can restore your personal data files and reinstall your third-party software.

    In the future never attempt to use any Windows disk utilities to fix or diagnose a Mac formatted drive.
  • mixedmedia Level 1 (0 points)
    Hi Kappy, thanks for the quick reply.

    I don't know if doing the steps you've outlined make any difference with what I've already tried (boot using the Tiger/Leopard disc, erase the hard drive and make a new partition when installing the OS).

    Anyway, I'll give it one last try using your steps to reformat my hard drive. If this doesn't work too, I guess it's time to change the HDD then. Bad luck.

    By the way, SMART status is still "Verified". It says verified but it does not act like it is verified. I'm losing hope.

    I've backed up all my data anyway, thanks for the advice

    Will get back if any changes occur.


    Message was edited by: mixedmedia
  • George Peters Level 4 (3,165 points)
    If you have Apple Care, install TechTool Deluxe from the disk provided and under options check the box to run a Surface Scan. this will check all the sectors on your drive for bad blocks. If it comes back with an error call Apple Support and give them the error code.

  • Kappy Level 10 (265,951 points)
    I don't believe this tool is reliable on a GUID partitioned drive. I would not use it. TechTool Pro is OK as is Disk Utility. If the drive had bad blocks it would be pretty obvious. A surface scan really wouldn't be needed. The constant repetitious clicking each time it hit the bad block would be enough. Also, DU's SMART info would report this if it's not an external drive.
  • George Peters Level 4 (3,165 points)
    Back blocks are not always so obvious like in the case above. I have seen drives with bad blocks where SMART status still reports Verified.

    If you do not have Apple Care you can download the trial version of Drive Genius and run a Drive Scan but you will need to boot up to an external drive in order to run the test. Though just booting up to an external drive is usually enough to determine that the internal drive is the problem.

  • Blackshuu Level 1 (0 points)
    I'm having the same problem with my iMac since a couple weeks ago. Every application just started hanging constantly. I tried to reinstall Leopard and erasing the disk takes around 10 minutes (without zeroing out the data) and the Leopard installed in about 8 hours when it usually took about 30 minutes. SMART status appears as verified and the disk is using GUID. Every application still hangs after reinstall, and I haven't installed anything after the reinstall.

    I do not have AppleCare since Apple doesn't support it in Puerto Rico.

    Any help will be appreciated, thank you.
  • SalsaDAL Level 1 (0 points)
    Since the last Apple software update, I'm having the same problem. Maybe that is the cause.
  • mixedmedia Level 1 (0 points)
    Hi all,

    That is exactly the problem I had previously. For all of your information, I had performed a scary dissection of my 20" iMac to replace the 250GB WD hard disk. It seems that that's the only solution as after the replacement, my iMac's working like new again. I tried reformatting the faulty hard drive and ran a benchmark on it, unfortunately, it still behaves really slowly, where write speed is less than 1MB/s.

    I changed the 250GB WD hard disk with a new 500GB WD hard disk and it's working just fine. If you still have the warranty, get Apple to change it for you. For my case, my warranty's over, so I took the risk of dissecting my iMac myself.

    I don't really know what's the real cause of this, it seems that few people have been experiencing the same problem now. I'm disappointed that the hard disk only last under 2 years
  • baw Level 1 (5 points)
    I'm encountering slow disk performance since updating to 10.5.5. This has been most noticeable while playing games. Games are now pausing for disk access where prior to 10.5.5 this pausing did not occur. I've checked the SMART status and ran DiskWarrior and found no problems. Hopefully a future Mac OS X update will correct this issue.
  • apatheticguy Level 1 (0 points)
    Thanks for the post.

    I did the same thing, bought a new 500GB drive. Unfortunately, the same intermittent slow results, especially on uncached read/write.

    I'm wondering if it could be the drive controller?
  • apatheticguy Level 1 (0 points)
    I'm having the same performance issues after one drive failure, and a brand new install.

    What's weird is how intermittent it is. For example, I downloaded 330MB file in under 5 minutes, which was the 10.4.11 update. However, attempting to install the update is on 90 minutes and counting !

    First launch of Safari took 5 minutes, then instantaneous. No hardware issues reported, no drive issues, etc.

    I don't get it.
  • Walter Stevenson Level 1 (10 points)
    Same issue. Brand new Macbook Pro with 2.8 intel duo, 4gb ram, 512mb video, and 7200rpm hard drive. This thing is just about maxed out and since day 1, I've had nagging performance issues where the harddrive gets hung up on the finder, mail, firefox, you name it. It seems to happen randomly--when I open Activity Monitor I'll see a huge spike in read or write on the activity tab, with no apparent cause. I ran XBench and found the that, in the Disk Test, my Sequential Uncached Read and Random Uncached Read & Write were PITIFULLY low (the write was about 1MB/sec).

    C'mon Apple Geniuses... HELP!
  • cruiseback Level 1 (0 points)
    Dear fellow Mac users.

    Thank you so much for posting this. After having spent hours on Google I was beginning to suspect that I was the only one with this exact same issue.

    I wrote a post on it here:

    Seems very similar to what you guys are experiencing.

  • cruiseback Level 1 (0 points)

    Last night my computer totally froze, like never before. I was trying to watch a video in FireFox. I then tried google:

    Not sure if this is an actual solution, but reading some of those links finally pointed my attention towards Minefield:

    After installing Minefield I haven't experienced nearly as many freeze-ups, and those that have been occuring have only been lasting 10-15 seconds. Before they could last up to ~4 minutes.

    Maybe this is a help to someone, maybe not. But I think it was worth mentioning
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