I'm setting up a CentOS 7 box as a BackupPC 4 server to back up Windows boxes on my LAN. I'm using an external 1.5 TB USB drive for the "pool". BackupPC deduplicates by saving all files in a pool, a directory hiearchy with each file named for the checksum of the file, and the directories acting as a hash tree to reach each pool file. A backup for a specific workstation is a directory tree of checksums and metadata that point into the pool for the actual file data. Incremental backups are reverse deltas from periodic "filled" backups of all files. I'm using rsyncd to pull changed files from the workstations.
I'm deciding which filesystem to use for my external drive. I'm thinking the main candidates are ext4 and xfs. What's the best filesystem for this application?
https://github.com/backuppc/backuppc
Repo for CentOS 7 users:
https://copr.fedorainfracloud.org/coprs/hobbes1069/BackupPC/