>It sounds like fragmentation is just a given when it comes to
backing up to disk?
It is a given when backing up to a FILESYSTEM and leaving backups on
the filesystem. VTLs don’t have this issue. And a disk staging system
won’t have it if you empty it every night.
>Also, when you say "set the minimum threshold lower so that more files
get deleted..."
>This confused me; I mean, isn't the fragmentation being caused by
so many file creation/deletions?
>Wouldn't increasing the amount of files being deleted also increase
the fragmentation?
If you have bigger amounts of free space
for new backups to write to, they will write their data to contiguous sections
of disk (i.e. unfragmented0 from the start. The best would be a completely
empty filesystem each night. All backups would be written on contiguous
sections of disk (i.e. unfragmented). But when you delete one file, followed
by writing another file, and so on, each file is being fragmented from the very
start. So if you tell it to delete sooner, you give the files more room to
work and thus write unfragmented.