Time Machine frequent hard drive access and error

[Techcomm]

First I would like to sincerely thank everyone on this forum for their time. I have been using windows from day one and have just switched about a month ago. I purchased an early 2008 24" iMac 2.8Ghz a month ago. It is awesome. This forum is amazing and was a great help in deciding to make the switch.

Two days ago hooked up an iomega ultramax 500 drive as my time machine drive. Installation was a breeze.

I notice it accesses the drive quite frequently. (Not just for hourly backups). Is this normal?
Also, I just received this error: "Time Machine error- Unable to complete backup. An error occurred while copying files to backup volume"
I clicked ok and then did a "backup now" which ran fine. Wonder what happened.

Should I be concerned about these two issues?
Thank you so much for your help.

 

[BlueRevolution]

How is the drive formatted? (Did you wipe it before configuring Time Machine?)

Has the error recurred?

 

[Techcomm]

The drive is an iomega UltraMax 500GB and was formatted HFS+ for mac out of the box. I just plugged it in via firewire and it installed perfectly. It ran a full backup and has been running hourly backups since then with no problems (two days).
I was just concerned about the error and the more frequent than hourly disc access.
Thanks for your help. I appreciate your time.

 

[BlueRevolution]

It's possible that Spotlight is just indexing. Next time the drive starts to go, take a look at the magnifying glass on the far right side of the menu bar. If there's a flashing dot in the middle of the lens, that means it's indexing.

 

[Techcomm]

It seems to be accessing the drive several times an hour. No flashing dot in the magnifying glass. Maybe this is normal?