Clicking on OK shows that the backup failed after backing up 4,295,194,412 bytes of data, which is 4 GB of data (4,295,194,412 bytes / 1,024 bytes/kilobyte / 1,024 kilobytes/megabyte / 1,024 megabytes/gigabyte).
The log file showed "End of Media encountered while backing up to non-removable media" and "The operation did not successfully complete."
I had been backing up the Exchange Information Store, which holds all users'
email on the Exchange server, to an
USB drive, but recently swapped
that drive with another drive when it filled. The new drive was formatted
with the FAT32 filesystem.
I had forgotten that the maximum size of a file that can be stored on
a FAT32 partition is 4 GB. The Wikipedia
File Allocation Article
states that it is acutally 4 GB - 2 bytes, i.e. 232 -2 bytes.
filesystem, which is a newer filesystem than FAT32, does not have that
limitation. NTFS can support partition sizes exceeding 2
TB.You can use the
command to convert a FAT32-formatted partition to NTFS.