A segment is repaired only when its number of pieces drops below a threshold. There’s no specific duration of downtime that triggers repair, rather, it’s the collective behavior of all nodes that host pieces of a given segment that determines whether that segment will be repaired. As such, if a segment you host already had several other nodes offline, you dropping from the network is likely to trigger repair. For most segments you can probably count on enough other nodes being still online for non-trivial time.
Per V137.5 - high load? - #54 by littleskunk, the threshold would be 46 nodes out of 54, so 7 other nodes would also have to be online for yours to trigger repair.
On top of that:
- satellites will not notice you being offline immediatelly,
- per 1 of 2 nodes died - #10 by Alexey pieces are not considered unhealthy immediately after the node is found to be offline, but only after 4 hours.
As an example, I had some >2 week downtime last year, and when getting back online, I lost maybe 20% of the pieces, probably less. This with different RS numbers though.