No problem.
The result from the last full backup was:
Code: Select all 1:02:27.22 03/02/2017 ### Backing up your OpenKM Files...
7-Zip [64] 15.14 : Copyright (c) 1999-2015 Igor Pavlov : 2015-12-31
Scanning the drive:
131694 folders, 20173 files, 14536712955 bytes (14 GiB)
Creating archive: [location]\Full_Backup\openkm_repository.7z
Items to compress: 151867
Files read from disk: 20139
Archive size: 10766276226 bytes (11 GiB)
Everything is Ok
3:01:58.24 03/02/2017 ###
Performance is circa 5GiB/hour for the maximum (-mx9), or ultra level of 7zip encryption. I would guess that the majority of the 20k files we have are scanned PDFs, so they are fairly well compressed in advance. I think the compression routine would be much faster if I switched to a lower level of compression (-mx3 or -mx5), without gaining a whole lot of archive size.
The result of the last differential:
Code: Select all 1:02:37.17 04/03/2017 ### Backing up your OpenKM Files...
7-Zip [64] 15.14 : Copyright (c) 1999-2015 Igor Pavlov : 2015-12-31
Open archive: [...]\Full_Backup\openkm_repository.7z
--
Path = [...]\Full_Backup\openkm_repository.7z
Type = 7z
Physical Size = 10766276226
Headers Size = 1157713
Method = LZMA2:26
Solid = +
Blocks = 4
Scanning the drive:
138013 folders, 22810 files, 16117143810 bytes (16 GiB)
Creating archive: [...]\04_03_2017\openkm_repository.7z
Items to compress: 10605
Files read from disk: 2680
Archive size: 1037489462 bytes (990 MiB)
Everything is Ok
1:14:00.73 04/03/2017 ###
You can see we have added or changed 2680 files in the last month. This added another couple of GiB to the total repo size. However, running a differential compression, even at max (-mx9) only takes 12 minutes. (This is still bang on 5GiB/hour performance).
We are using MySQL installed to [base install location}\database. The sql dump file is about 500Mb, but compresses down (with some much smaller and unconnected sql dumps) to less than 30Mb.
Hope this helps.