wal_segment size vs max_wal_size

There is apparently some misbehavior if max_wal_size is less than 5 *
wal_segment_size.

For example, if you build with --with-wal-segsize=64, then the recovery
test fails unless you set max_wal_size to at least 320MB in
PostgresNode.pm.  The issue is that pg_basebackup fails with:

pg_basebackup: could not get transaction log end position from server:
ERROR:  could not find any WAL files

This should probably be made friendlier in some way.  But it also shows
that bigger WAL segment sizes are apparently not well-chartered
territory lately.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services