Every time same error

[createa]

I have My Book Essential 2Tb.

When I do reformatting disk it looks ok and I start to use it for Time Machine backup. First backup (about 500 Gb) usually done succesfull but next sessions ends with error message then I start to verify disk in Disk Utility and always see the same strings:

Verifying volume “Backup”

Checking file systemChecking Journaled HFS Plus volume.

Checking extents overflow file.

Checking catalog file.

Checking multi-linked files.

Checking catalog hierarchy.

Checking extended attributes file.

Checking multi-linked directories.

Checking volume bitmap.

Volume bitmap needs minor repair for under-allocation

Checking volume information.

The volume Backup was found corrupt and needs to be repaired.

Error: This disk needs to be repaired. Click Repair Disk.

After that I repeat all operation (formatting and full backup) and face this problem again and again.

So I suppose there is perhabs two problems:

1. Disk corrupted

2. Power supply issue causing controller problem

Is there any way to detect problem exactly?

[Wizer]

The drive is corrupted

you can try first aid but the same thing might happen

replace the drive if possible