Borg: What is the data utilization for borg mount?

Created on 9 Nov 2020 · 5Comments · Source: borgbackup/borg

Have you checked borgbackup docs, FAQ, and open Github issues?

Yes

Is this a BUG / ISSUE report or a QUESTION?

Question

System information. For client/server mode post info for both machines.

Your borg version (borg -V):

1.1.14 and 1.1.13

Operating system (distribution) and version:

Debian 10 (client - backup source), Synology DSM (server - backup destination)

Hardware / network configuration, and filesystems used.

Client - Backup Source
Debian 10 - borg 1.1.14 + borgmatic
FTTH connection, 1Gbit down, 200 Mbps upload
ext4
Server - Backup Destination
Synology DSM 6.2.3 - borg 1.1.13
VDSL connection, 70 Mbps download, 20 upload
ext4

How much data is handled by borg?

It's going to be 6TB at least. The first full fat backup will be done locally, then about 15-20GB over Internet/SSH every week.

Full borg commandline that lead to the problem (leave away excludes and passwords)

Describe the problem you're observing.

Hi,
I am setting up a borg environment to backup all of my personal data from my current server to my old Synology NAS in another city.
I am new to borg and I apologize if this is a noob question.

My question is regarding the actual network usage needed to restore one or a little number of files.
If I need a full restore I will obviously do it locally, but what happens when I want to restore one or some files? My backup server has a peasant 20 Mbit upload which _can_ be challenging.

As far as I understood, borg extract will restore a full backup, so I'm not going to use that remotely, but what about borg mount?
Does it only use metadata or similar to display files, or it still needs to extract all archives from a backup?

Additionally, where these "temp" files/archives are stored?

documentation question

Source

auanasgheps

All 5 comments

I think you should be fine with 20Mbit/s.

You can also do a partial extraction with borg extract, see the docs.

Similarly, you can do a partial mount with borg mount. Like:

only 1 archive
only a specific directory

borg mount keeps the filesystem structure in memory (the essential metadata), but fetches data on-access only.

ThomasWaldmann on 9 Nov 2020

TODO: check the docs if we they are clear enough about partial extract/mount. check if there are examples.

ThomasWaldmann on 9 Nov 2020

borg mount keeps the filesystem structure in memory (the essential metadata), but fetches data on-access only.

That's great, that's what I wanted to know (and I hoped). It's a very useful info, which I could not find in the docs.

I will also try the specific directory mount, since is the one I'm likely going to use.

auanasgheps on 9 Nov 2020

👍1

I've managed to test this scenario with a "small" test backup of 10GB and it is behaving as you described:

Mount is quick (bunch of seconds) with minimal network transfer
Files are being transferred only when copied or opened

I am shocked how easy and swift borg mount works.
@ThomasWaldmann it definitely needs to be advertised, why this is not on the homepage and in docs?

I will donate to this project as soon as I can :)
My questions are over, this can be closed unless you want to keep it as a TODO for the docs.

auanasgheps on 9 Nov 2020

Notes:

How quick it is depends on the archive size and many other factors.

"Mountable backups with FUSE." is on the homepage.

Thanks for donations. Generic funds donations via bountysource will get put on tickets and whoever works on the tickets (== works on borg) will get the bounty.

ThomasWaldmann on 9 Nov 2020

👍1

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