Why is backup software so slow? For comparison, a straight file-copy job in Windows or the command line goes at the rate of about 100 GB/hr.
- It doesn't matter if you are backing up to a USB-attached external hard disk, a NAT device or an eSATA hard disk; the rate stays the same (20-25 GB/hr).
- It doesn't seem to matter what the software is either - Backup Exec, NTBackup, et al.
- Curiously, backing up a single file, like an Exchange data store, runs more quickly - 40 GB/hr.
- Write a batch file to copy files that are not open/locked by running services. Then schedule the batch file to run every night.
- Use backup software to backup files that are open/locked.
Backup software uses the Volume Shadow Copy Service (VSS) to make/use shadow copies of files to get around the access/sharing problem.
There are at least two problems with my solution:
- Some if not all of the batch-file/command-line copy commands do not handle long file names gracefully.
- It is messy and not always obvious which files need to be backed up versus those which can be copied.