You really haven't given us much to go on here. What type of backup are you doing? For example is it a File system backup, and Applications Integration backup, a VMware backup, something else? What is teh full text of the error? You can edit it to take out specific machine names
The snippet you included indicated a segmentation fault, which means a Core file was probably created. It is coming from the VBDA (Disk Agent) module. I did find one lab case with the 'libc-2.12.so' error, but that was for DP 7.0 and was coming from the Media Agent. This was resolved by getting current with patches
I found a fix when doing a VMware backup which was implemented in the 6.21 patch bundle. There were a lot of fixes made in this patch bundle, and, if you are oly on 6.20, I would recommend that you upgrade to 6.21, and install subsequent patches
I suggest that, if you are not on 6.21, to download the patch bundle from
http://support.openview.hp.com/selfsolve/patches
You will need to have a UNIX-based (HPUX, Linux or Solaris) Installation server to download this patch bundle. Get teh bundle installed, and also download the subsequent patches that you will find on the same site. For this issue, I recommand that you download and install at least the Core and Disk Agent patches