I have a hierarchy of about 270k files, taking about 20 GB (many small files)
On Linux (Unbuntu 19.04, ext4), it takes 7 minutes to back them up and 6 minutes to restore them. That’s very fast.
But to check the storage with duplicacy --files --stats, it takes 2 hours! For only one revision. Without --files it’s only a tenth of a second.
What could --files be doing that takes so long? My understanding is that it reads the contents of each file from the archive, computes the hash on it and checks it against the hash stored for the file in the backed up archive. How could that possibly take that long, when the backup operation itself which also, fully reads the contents of each files and calculates the hash, in order to store them in the archive, only takes 7 minutes? Granted it reads the file contents from the file system rather than the duplicacy archive, butit shouldn’t be that big of a difference, since the restore operation, that reads file contents from the archive, also takes very little time?
For the same files, stored on NTFS and running duplicacy on Windows, I get 18 mins for the backup, 32 mins to restore, but over 2 hours to check. I’m fine with the backup and restore times being a bit longer than on Linux, but again the check is unjustifiably slow.
Also, for the same files, on Linux, borg check with --verify-data (the slowest option) takes only 3.5 minutes (and similar backup/restore times to duplicacy).
This is all backing up from an SSD onto another local drive, so no network/internet download/upload involved.
Here is the output on Linux:
meubuntu@meubuntu-Virtual-Machine:~/mine/Me$ time duplicacy check --files --stats
Storage set to /home/meubuntu/mine/duplicacy_backup1_native
Listing all chunks
1 snapshots and 1 revisions
Total chunk size is 10,783M in 3125 chunks
All files in snapshot e_me_native at revision 1 have been successfully verified
Snapshot e_me_native at revision 1: 270090 files (19,553M bytes), 10,783M total chunk bytes, 0 unique chunk bytes
Snapshot e_me_native all revisions: 10,783M total chunk bytes, 10,783M unique chunk bytes
real 120m31.079s
user 132m53.507s
sys 3m15.797s
meubuntu@meubuntu-Virtual-Machine:~/mine/Me$ time duplicacy check --stats
Storage set to /home/meubuntu/mine/duplicacy_backup1_native
Listing all chunks
1 snapshots and 1 revisions
Total chunk size is 10,783M in 3125 chunks
All chunks referenced by snapshot e_me_native at revision 1 exist
Snapshot e_me_native at revision 1: 270090 files (19,553M bytes), 10,783M total chunk bytes, 10,783M unique chunk bytes
Snapshot e_me_native all revisions: 10,783M total chunk bytes, 10,783M unique chunk bytes
real 0m0.147s
user 0m0.063s
sys 0m0.039s