The following error is seen in the server CLOG for a client node:
FBSS7554E We have found a problem with MBR on disk (0x#######). Volumes on this disk can not be protected.
This could be caused by a discrepancy between the size and length of the drive(in sectors).
Diagnosing the problem
The following tool can be run on the system to diagnose the issue:
The tool can be run from a DOS command prompt and the output can be piped to a file with the following syntax: getdata.exe > getdata.out
Review the output file for the following section:
************* The New DB **************
Disk HP LOGICAL VOLUME 5.70 signature 0x6b5e81cd, Size (sectors) 143305920, LUN 
MS signature 0x6b5e81cd
|Disk |Start sector|Length |Signature |
| | | | |
| 000 | 0000002048 | 143304704 | b96593ba |
Compare the Size against the Length (both high lighted in bold above). The size should not be greater than the length. In the example above we can see that the size is greater and causing the FBSS7554E error.
Resolving the problem
This issue is not caused by Fastback and needs to be corrected before the client will function properly. Please contact Microsoft for assistance in resolving this discrepancy.
FSBK fastback backup volume MBR failed connection socket