How to big scale backup Gitlab?
I would review what you are backing up and possibly use a "multi-path" approach. For example, you could backup the Git repositories by constantly running through Git pulls on a backup servers. That would copy only the diff and leave you with a second copy of all Git repositories. Presumably you could detect new repos with the API.
And use the "built-in" backup procedures to backup the issues, etc. I doubt that the 3TB comes from this part so you would be able to do backups very often at very little cost. You could also set up the PostgreSQL database with a warm standby with replication.
Possibly your 3TB comes from container images in the Docker registry. Do you need to back those up? If so, then there may be a better approach just for that.
Basically, I would recommend really looking at what it is that makes up your backup and backup the data in various parts.
Even the backup tool from GitLab has options to include/exclude certain parts of the system such as the Docker Registry.
For such a short time between backups (1h), your best bet is to rely on filesystem-level snapshot and
If using ZoL is not a problem in your environment, I would strongly advise to use it. ZFS is a very robust filesystem and you will really like all the extras (eg: compression) it offer. When coupled with
sanoid/syncoid, it can provide a very strong backup strategy. The main disvantage is that it is not included into mainline kernel, so you need to install/update it separately.
Alternatively, if you really need to restrict yourself to mainline-included stuff, you can use BTRFS. But be sure to understand its (many) drawbacks and pita.
Finally, an alternative solution is to use
lvmthin to take regular backups (eg: with
snapper), relying on third party tools (eg:
blocksync, etc) to copy/ship deltas only.
A different approach would be to have two replicated machines (via
DRBD) where you take indipendent snapshots via