Follow these steps to restore a dump.rdb into a Redis master that is running in append-only mode. For some reason this is not documented very well. The master in this case had an issue and was unable to write to disk. I was able to get the dump.rdb from a slave.
Step 1 - Obtain a dump.rdb & check the size for later comparison
redis-cli -p $PORT save redis-cli -p $PORT dbsize
Step 2 - Stop the master & all slaves
Step 3 - Update the Redis working directoryRemove any old dump.rdb files and any old appendonly.aof files. Place the dump.rdb that is to be restored in this directory.
Step 4 - Update the master conf fileTurn off appendonly or else Redis will create a new zero-size appendonly.aof and a new dump.rdb.
daemonize no loglevel verbose logfile stdout appendonly no #Important part
Step 5 - Start Redis in the foreground and watch for errors
Step 6 - Connect to Redis in a separate consoleDBSIZE should return the same size as before. The BGREWRITEAOF command generates a new aof file.
redis-cli -p $PORT DBSIZE BGREWRITEAOF
Step 7 - Put everything back the way it was
Once the aof file has been completely written, update the redis.conf file options back to appendonly=yes and daemonize=yes.
I hope this was useful!