I have a 2 host setup: master & replica.
Both hosts share a NAS directory mounted at /backup, which is where pg_backrest backups and WAL archives are saved.
We had a recent outage where WAL logs and pg_backrest could not save to /backup, and as a result the replica got really behind. The situation has since been resolved in terms of getting WAL logs and backups correctly being archived into /backup.
I just did a restore on my replica using the most recent backup instead of having it catch up via WAL logs.
After starting the replica back up, I noticed that it was no longer doing streaming replication. Also I noticed the logs said something about not finding WAL logs that it expected to find (not sure if these two things are related).
2016-03-17 14:14:40.601 T00 INFO: getting WAL segment 00000001000002020000001D
2016-03-17 14:14:40.858 CDT [2635-107]: LOG: restored log file "00000001000002020000001D" from archive
2016-03-17 14:14:41.214 T00 INFO: getting WAL segment 00000001000002020000001E
2016-03-17 14:14:41.216 T00 INFO: 00000001000002020000001E was not found in the archive repository
2016-03-17 14:14:41.235 CDT [2635-108]: LOG: redo done at 202/1DFFFE78
2016-03-17 14:14:41.235 CDT [2635-109]: LOG: last completed transaction was at log time 2016-03-17 14:13:18.23722-05
2016-03-17 14:14:41.527 T00 INFO: getting WAL segment 00000001000002020000001D
2016-03-17 14:14:41.755 CDT [2635-110]: LOG: restored log file "00000001000002020000001D" from archive
2016-03-17 14:14:41.964 T00 INFO: getting WAL segment 00000002.history
2016-03-17 14:14:41.967 T00 INFO: 00000002.history was not found in the archive repository
2016-03-17 14:14:41.992 CDT [2635-111]: LOG: selected new timeline ID: 2
2016-03-17 14:14:42.197 T00 INFO: getting WAL segment 00000001.history
2016-03-17 14:14:42.199 T00 INFO: 00000001.history was not found in the archive repository
2016-03-17 14:14:42.262 CDT [2635-112]: LOG: archive recovery complete
2016-03-17 14:14:42.263 CDT [2639-1]: LOG: checkpoint starting: end-of-recovery immediate wait
2016-03-17 14:15:16.906 CDT [2639-2]: LOG: checkpoint complete: wrote 166544 buffers (31.8%); 0 transaction log file(s) added, 0 removed, 0 recycled; write=1.744 s, sync=32.890 s, total=34.643 s; sync files=551, longest=3.991 s, average=0.059 s