Greyhole Default Operation for --fsck and Balancing Queries

[astrom0]

Thanks for the advice provided at Issues #275: Recommended landing zone disk size and thanks for the software. Off the back of the Issue #275 discussion, I'm seeking to better understand how Greyhole (GH) works out of the box in terms of what it does automatically. Then from that understanding, overlay my specific needs on top of GH's default function and then seek to configure my system to maximise the potential of GH.

So, the basic questions are:

1. If GH is left to its own devices without external intervention, what triggers an --fsck event and at what frequency?

2. Similarly, what triggers a --balance event and at what frequency?

For Q. 1, I've found Issue #310 and from the file:
/etc/cron.daily/greyhole
I can see that this action runs:
/usr/bin/greyhole --fsck --if-conf-changed --email-report --dont-walk-metadata-store > /dev/null
once per day, as per the specification in:
/etc/crontab

So, by default, is that the only automatic trigger for running --fsck?

Q. 2, how does balancing work?

From what I can gather, balancing is a user initiated activity. There doesn't appear to be a background, automatic trigger. Have I got that right or is there something I'm missing?

Please help me understand the functionality of GH better. In advance, thanks for the feedback.

As a side note for context, there's a run down of how I use GH refer here:
Discussion #335: Preferred Backup Synchronisation Tool Poll
In summary, I use GH on a periodic basis as a cold storage back up tool using file synchronisation with a NAS on demand. The GH box runs 2 x 6 TB HDDs and 3 x 3 TB HDDs + 120 GB SSD loaded with GH on a Xubuntu OS. So, I want to understand if I'm missing something about how GH functions that would be of use to me.

[gboudreau]

There are 3 cron files that are installed, when you install the packaged version of Greyhole:

• https://github.com/gboudreau/Greyhole/blob/master/greyhole.cron.d
• https://github.com/gboudreau/Greyhole/blob/master/greyhole.cron.daily
• https://github.com/gboudreau/Greyhole/blob/master/greyhole.cron.weekly

The first lists jobs that run on boot, and every minute (process the Samba spool).
The daily one will run fsck if your config file changed, because config changes could affect file copies, for example, if you change the configured file_copies.
And the weekly one will run fsck unconditionally.
Those were designed as safeguards for users who would go against recommendations and play with the files on their pooled drives, or with the files in the LZ.

Balancing is never triggered automatically. It was designed to run when you add or remove storage to your pool. There is no reason to run it otherwise, because using Greyhole as recommended (through Samba), and even fsck, will choose the appropriate drives to work with, and thus you'd end up with fairly balanced drives.