Rebuilding the file index

Server is 2.2.5 on Ubuntu 16.04.3… backups are going to a 27tb btrfs mirror with 11tb used. Write speeds are good on /var/urbackup drive and the backups btrfs drive… about 200 clients, essentially all incremental file backups and a mixture of windows and mac clients… anyways:

I reluctantly began a rebuild and defragmentation of the database and now I believe the file index has been rebuilding extremely slowly. Its been about 24 hours and the web interface shows…

“Number of file entries processed: 5979977
Percent finished: 28.3294”

Should it take this long? What exactly is it doing? Is there any documentation and defrag and rebuild? A four day rebuild sounds like a bit much?

the issue was with the hard drive being used for /var/urbackup … swapped it out and the file index rebuild went extremely faster.

See also the tuning tips in (allow more dirty memory). This is a global setting unfortunately and applications cannot change it for a single file.