My Book Elite Slows to uselesness

My Book Elite (1 TB) purchased 2 mos ago was initially formatted for windows and immediately reformatted for MacOSX. It has been used for photo storage exclusively so far. It is USB wired to an iMAC 8.1 operating with OSX 10.6.7 Snow Leopard, 2.66 GHz Intel Core2 Duo with 4 GB 800MHz DDR2 SDRAM and L2 Cache =6MB. The video card is ATI Radeon HD2600 Pro (VRAM = 256 MB). It has been working beautifully via Adobe CS5 (Bridge and Photoshop) until loading the last batch pictures from camera to a new file on the drive. Then it became interminably slow to access or write files to (USB connection). The PS cache is set to 20 history states; tile= 3 levels; tile cahe size 1024 and 70% memory allocation. The files are mostly .jpeg and .nefs (write-back size = 10.4 MB).

The Ext HD Drive has 54 GB used and 945 GB available.  The IMAC HD has 187 GB used and 182 GB available.

I have, to little avail: 1. rebooted in safe mode

  1. Repaired iMAC HD permissions (Can’t repair MyBook permissions b/c drive “failed to unmount”)

  2. Trashed Bridge .plist and PS .plist

  3. Purged Bridge Cache

  4. Moved new folder containing recent images from MyBook to iMAC desktop - Photoshop reads and writes to it beautifully. MyBook ext drive remains slow with remaining folders. I mean really slow. Uselessly slow.

  5. Changed USB ports 

Is there some periodic necessity to defragment this disk or housekeep it in some other way? Is this necessary or even possible with the MAC?

I believe the drive is fine based on its response to “eject” , startup and lite lit when trying to access.

So what am I missing?

You can go to Disk Utilities and try First aid to repair the disk. That is Mac form of scan disk.

Thank you Lawrence. That seems to have done the trick. I am rather new to Mac. Appreciate the help!

No problem always glad to help!