I have a Windows Server 2003 R2 box, used as a file server, and backup DNS server for our domain. I use BackupAssist to schedule NTBackup to do weekly full backups and daily differentials. The backups are stored on a SATA hard drive in a removable tray on a Windows 7 (64 bit) PC on the same LAN.
Starting a couple months ago, the full backups fail to verify very close to the end. For a while, if I re-ran the full backup manually the following day, it would succeed with no issues. Now they fail 100% consistently either scheduled or manual. The smaller daily backups always succeed.
I have updated the NIC drivers on the server, and tested using only a single NIC. I disabled all of the advanced options on the NICs. I have swapped to a different drive tray, which was confirmed good hardware by SpinRite the night before I brought it in. None of these made any difference.
The only successful full backup I've done has been to a USB drive attached directly to the server.
Have I missed something stupid?