Dblock size recommendations?

[jan_reinhardt]

Hi,
default dblock size is 50 mb. Its said to work best for remote i.e. cloud backups.
But I couldnt finde actual dblock size recommendations for local backups in my own LAN.
On a different machine, but within my own Gbit network: what are recommended file sizes? 100 mb? 500 mb?
Does it depend on the data size youre backing up? In my case, the amount of data to back up is just 3 gb.

Thank you!

[kenkendk]

@jan_reinhardt

But I couldnt finde actual dblock size recommendations for local backups in my own LAN.
On a different machine, but within my own Gbit network: what are recommended file sizes? 100 mb? 500 mb?
Does it depend on the data size youre backing up? In my case, the amount of data to back up is just 3 gb.

Hi @jan_reinhardt welcome to the forum and thanks for the question.

There is a general overview here:

Choosing sizes in Duplicati

Choosing Sizes in Duplicati All options in Duplicati are chosen to fit a wide range of users, such that as few as possible of the users need to change settings. Some of these options are related to sizes of various elements. Choosing these options optimally is a balance between different usage scenarios and has different tradeoffs. This documents explains what these tradeoffs are and how to choose those that fit a specific backup best. The block size As Duplicati makes backups with blocks, aka…

The summary is that it depends on your requirements. Duplicati only works on volumes (aka .dblock files), so if you restore a 1 byte file, Duplicati needs to download/copy the entire volume (optionally decrypt it) and extract the single byte file.

To reduce the overhead here, a smaller size is desired. The flipside is that each volume has a bit of overhead in terms of fetching, headers, tracking, etc.

But you can roughly divide the backup source size with the volume size and figure out how many volume files will be created.

For LAN setups, I think somewhere in the range of 100 MiB to 5 GiB would make sense.
But for a 3 GiB source, you will have roughly 3000/50 ~= 60 remote volumes, so there is no real benefit in increasing the remote volume size.

If you get into thousands of remote volumes, I would consider increasing the volume size to make it perform better on the local filesystem.

[jan_reinhardt]

thanks! I will try it out with 50 mb and with 500 mb and see if things smell differently