More monitoring

[LeeSmet]

The current code only monitors the backend data 0-db's, and has very limited info about internal operations. We can add a lot of stuff, to give more insight in how the system behaves.

• Monitoring of metadata backends (see Better metadata reliability #57 and Monitor metadata backends #61)

• Monitoring of capacity pools we manage (Monitor capacity pools #64)

• An optional monitor for 0-db-fs. An Ioctl can be used to query info from the filesystem. This is useful as 0-stor is usually deployed next to 0-db-fs as part of the qsfs stack. (Support extracting zdbfs metrics #65)

• Monitor the wallet balance (Monitor wallet balance #67)

• More internal items, which should also help to tune the system (Improve metrics of internal system actions #66)??

[weynandkuijpers]

Sorry - closed the issue by acciddent.

[LeeSmet]

Considering the coverage which is currently available I'll close this. The added internal metrics will be kept open as a tracking issue in case debugging shows we have missing info, though I think the current metrics should be sufficient.