How do I find out the "redo log file max size" in Oracle 11R2
If you want the size of the redo log members (files on disk) size, then use the query below:

-- Show Redo Logs info
set linesize 300
column REDOLOG_FILE_NAME format a50
SELECT
    a.GROUP#,
    a.THREAD#,
    a.SEQUENCE#,
    a.ARCHIVED,
    a.STATUS,
    b.MEMBER    AS REDOLOG_FILE_NAME,
    (a.BYTES/1024/1024) AS SIZE_MB
FROM v$log a
JOIN v$logfile b ON a.Group#=b.Group# 
ORDER BY a.GROUP# ASC;


The query output should look like:

GROUP   #THREAD#  SEQUENCE# ARC STATUS   REDOLOG_FILE_NAME      SIZE_MB 
---------- ---------- ---------- --- ---------------- ---------------------
1       1       4 YES INACTIVE /ORACLE/oradata/orcl1/redo01.log   50 
2       1       5 YES INACTIVE /ORACLE/oradata/orcl1/redo02.log   50 
3       1       6 NO  CURRENT  /ORACLE/oradata/orcl1/redo03.log   50