I am going to sync slave with my master which is almost 500 G. I am not using archive directory instead of I am using wal files for streaming. As it may take almost 3 hours, I am thinking of setting up 400 for wal_keep_segments where I have enough space available.
Without the space issue, could there be any other problem in setting up such high value for "wal_keep_segments"? As this is production, I need to confirmed.
Another data point: I set up SR on two systems recently in production with the wal_keep_segments set to 10000 (lots of logs were being generated), and the slaves were about 1TB each. No problems were experienced.
