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Yesterday I have replaced my MacBook Pro's faulty, 250GB HD with a new 750GB WD Scorpio Blue HD and then restored my data using a TimeMachine backup that I had stored on a separate WD HD. The restore completed successfully and the new HD was recognized by the Macbook.

However, I now notice severe performance drops when using my MacBook, even when performing just minor tasks as my OS will freeze every 5-10 seconds (beach ball) and will remain frozen for about the same period. Even when I try to login, the beach balling starts. This doesn't just affect one app, this issue appears to be system wide as everything will freeze until the clock freezes. Music playback is interrupted as well and resumed after the beachballing has stopped.

At first I thought that maybe an app of mine was overusing the CPU, but that was not the case. Other than Activity Monitor, all apps use between 0% and 0.1% CPU. RAM can't be an issue either as my MacBook Pro has 8GB RAM and these issues occur even if I am not running any apps myself. (and Mac OS X Lion uses about 1.1GB RAM)

Here're some things I tried:

  • Letting the Spotlight Index finish. This took a few hours, but has completed ok.
  • Checking the SMART status of the HD. It is set to verified.
  • I ran a disc verify in Disc Utility. This came back as OK.
  • Repairing disc permissions. This changed nothing.
  • Cleared out caches. No change in behavior.
  • Checked Defrag status using Drive Genius 3. The graph shown by Drive Genius indicated that a defray wasn't needed, which is a bit obvious as the HD is brand new.
  • I cannot do a clean install at the minute as it would take me a very long time to move my files around again. Rest assured though that I don't have any "crapware" installed - I'm a developer who naturally looks at apps a little more critically.

Has anyone experienced issues like this? My MacBook ran fine with its old HD (when the HD worked), so why this sudden change in behavior?


Sent the HD back to Western Digital for a full refund as it certainly wasn't the quality I paid for. I had however had a great experience with the replacement I purchased from Amazon, a Toshiba MK5061GSY (£72) which runs at 7200RPM and has displayed no such behavior.

share|improve this question
What kind of values are you getting for IO/sec and Write Speed in the Disk Activity section of Activity Monitor? – Joseph Redfern Apr 8 '12 at 21:56
IO Peak: 137 IO/sec Data Peak: 876kb/sec to 2MB/sec, varies every few seconds or so. – Pripyat Apr 8 '12 at 21:59
Data Peak now 5.3MB/sec, IO 159 IO/sec – Pripyat Apr 8 '12 at 22:01
Seems kinda high to me... but not outrageous. Is that when your machine is idling? – Joseph Redfern Apr 8 '12 at 22:05
I had Safari open with 2 tabs when I checked in Activity Monitor. – Pripyat Apr 8 '12 at 22:06

I had the same issue; lots of freezes and kinda big numbers in disk activity.

The fix was pretty simple in my case. I had to add Bootcamp to Spotlight exceptions to not be indexed. This lowered the numbers from 5-7 MB/s to a few KB.

share|improve this answer
The HD had a fault and was replaced. – Pripyat Sep 14 '13 at 8:19

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