Replication and Binary Logging Options and Variables •If you need to put the relay logs in some area other than the data directory because your relay logs tend to be very large and you do not want to decrease  max_relay_log_size . •To increase speed by using load-balancing between disks. • relay_log_basename • relay_log_index You can obtain the relay log file name (and path) from the  relay_log_basename  system variable. Holds the base name and complete path to the relay log file. The maximum variable length is 256. This variable is set by the server and is read only. The name for the relay log index file. The maximum variable length is 256. If you do not specify this variable, but the  relay_log  system variable is specified, its value is used as the default base name for the relay log index file. If  relay_log  is also not specified, then for the default replication channel, the default name is  host_name -relay-bin.index , using the name of the host machine. For non-default replication channels, the default name is  host_name -relay-bin- channel .index , where  channel is the name of the replication channel recorded in this relay log index. The default location for relay log files is the data directory, or any other location that was specified using the  relay_log  system variable. You can use the  relay_log_index  system variable to specify an alternative location, by adding a leading absolute path name to the base name to specify a different directory. The relay log and relay log index on a replication server cannot be given the same names as the binary log and binary log index, whose names are specified by the  --log-bin  and  --log-bin-index options. The server issues an error message and does not start if the binary log and relay log file base names would be the same. Due to the manner in which MySQL parses server options, if you specify this variable at server startup, you must supply a value;  the default base name is used only if the option is not actually specified . If you specify the  relay_log_index  system variable at server startup without specifying a value, unexpected 3520 Command-Line Format --relay-log-index=file_name System Variable relay_log_index Scope Global Dynamic No SET_VAR  Hint Applies No Type File name Default Value *host_name*-relay-bin.index System Variable relay_log_basename Scope Global Dynamic No SET_VAR  Hint Applies No Type File name Default Value datadir + ’/’ + hostname + ’-relay- bin’