For some more numbers: I have a file server
with 700GB of data in 400,000 files that takes about 5 hours for an incremental,
and about 13 hours for a full. I have another server that is 3,000GB
(3TB) big with 1.4 Million files and it takes about 50 hours for a full
and about 20 hours for an incremental. Both are *substantially* faster
I'll throw in some of my own numbers here, purely because it's quite interesting to compare.
I have a server with 9 million files - a full takes 49 hours whereas an incremental takes 6 hours. This is across around 500GB of data.
Another has 2 million files - a full takes 10 hours whereas an incremental takes 75 minutes. This is across around 375GB of data.
If we look at one more - with 72 thousand files - a full takes 30 minutes whereas an incremental takes 5 minutes. This is across around 20GB of information.
My BackupPC box is fairly old and is running on 2x Opteron 2212 @ 2Ghz ea. - though it does have 32GB of RAM. The filesystem is running xfs and is mounted from a SAN over iSCSI running disks in RAID-1.
Hope this is of some interest for those who like comparing!