Not that I'm aware of. This feature was targeted at smaller form-factor platforms (e.g. SRX) that don't have full blown hard drives like the MX (hence why you see it say unsupported). SRX also has another statement to specify the number of rollbacks stored on the flash as well.
I work with some devices that have massive configurations (~450000 lines / 16M),...
You have a few options. First, you can simply output everything to the terminal and copy/paste into a text file. For this, you would run:
show configuration | no-more for stanza formatted configuration. This is usually easier to read given you can see the hierarchy.
show configuration | display set | no-more for "set" format, which may be ...
First a quick note (even though it might not be terribly relevant for you) /var/rundb/private and /var/run/db/private are symlinked.
I digress, /var/run/db/private is a directory used to manage configuration state for configure private mode. You can delete the contents, but DO NOT delete the actual directory structure. Before doing so, I would double check ...
The partition table shows the partition level. Usage within a partition is up to the file system.
The article you've linked to suggests (pre Junos OS 15.1 / FreeBSD 6.1):
show system storage | match "/dev/ad0s1a|/dev/ad1s1f"
or (Junos OS 15.1+ / FreeBSD 10):
show system storage | match "/dev/gpt/junos"
On JunOS OS 15.1+, the Compact ...
what's the usage of them?
Those seem to be automated configuration and database backups. Check the retention settings for those backups - you might want them deleted past some point and not keep piling up forever.
You haven't shown us the device config, so we can't tell.
I have found answer from the Juniper documentation as below:-
The graceful Routing Engine switchover (GRES) feature in Junos OS and Junos OS Evolved enables a router with redundant Routing Engines to continue forwarding packets, even if one Routing Engine fails. GRES preserves interface and kernel information. Traffic is not interrupted. However, GRES does ...