A common backup practice these days is to have a huge disk drive serve as a backup repository. The backup software creates some sort of container file (i.e. .vbk) on the drive and periodically older backups are purged off the system. There is nothing wrong with this practice if you properly maintain the drive.
We were recently contacted by a user looking to speed up their backup times. During their testing they came back to us saying PerfectDisk had been running for 8 days and it had only defragmented slightly more than half the disk. We had no idea how badly the disk was fragmented so we asked them to send us the pre-defrag disk statistics and this is what we found.
- Drive size: 50TB
- Total Files: 1,273
- Total Fragmented Files: 913
- Total Free Space: 7.2TB (14%)
- Total File Fragments: 169,493,764
- Fragments/File: 185,645
- Free Space Fragments: 20,482,304
- Free Space Fragment Size: 302KB
- Largest Chunk of Free Space; 310GB
When older, fragmented backup files are purged from the system they leave “holes” of free space on the disk. In this case over 20 million holes, with an average size of 302KB. When new, large backup files are written to a disk with badly fragmented free space NTFS/ReFS have no option but to fragment the file. This user had over 30 files in more than 1 million fragments and the worst was in over 15 million fragments.
Microsoft has written numerous TechNet articles on the need for file defragmentation. The VMware documentation recommends to “Defragment the file systems on all guests”. They both recognize file and free space fragmentation kills performance. Virtual servers use the same OS and file system as physical servers with the same behavior.
System administrators have a choice, they can be proactive and prevent a problem, or they can be reactive and fix one. Fragmentation is a given with Windows, the same actions that caused this problem occurs on every system and drive.
PerfectDisk defragments files and consolidates free space better than any other solution available.