Memory usage and High water mark
Couchbase 1.8 with 4 nodes in AWS
So I've noticed on one my buckets that holds 8 million keys has a memory usage (4.8G) above that of the High water mark (4.2G) I've read the documentation here http://www.couchbase.com/docs/couchbase-manual-1.8/couchbase-bestpractic... which says that the high water mark is set by default to 70% of the memory available to the node (6.4GB)
The documentation here http://www.couchbase.com/docs/couchbase-manual-1.8/couchbase-bestpractic... that implies that memory usage above the high water mark is a bad thing, because some keys will be evicted to disk rather than kept in memory.
I know I can use cbflushctl to set a higher high water mark, but I'm concerned about the effect this will have on the rest of the buckets / overall cluster health. Is there any reason I shouldn't (for example) set the high water mark at 5G? Each node has 7.5G of RAM.
Any guidance would be appreciated.