In some situations the PostgreSQL stats collector process will have high I/O. More accurately; it has I/O that the administrator thinks is excessive - it really may not be.
In one circumstance, the complaint was caused by a steady 1.8KB/s write over a 24h period. That really is not very much for a large; active database.
Regardless, to reduce the I/O required by PostgreSQL there are a few tricks.
iotop is very good a measuring and displaying the I/O.
~ # iotop -o TID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 27709 be/4 postgres 0.00 B/s 1381.06 K/s 0.00 % 1.97 % postgres: stats collector process Total DISK READ: 0.00 B/s | Total DISK WRITE: 1381.52 K/s
postgresql.conf with the following setting.
autovacuum = off
Make this change and restart the PostgreSQL server; the I/O for stats collector should now be near zero. This may be a bit extreme; the autovacuum tool can be useful (but your DBA should decide).
autovacuum = on log_autovacuum_min_duration = 200 autovacuum_max_workers = 1 autovacuum_naptime = 960 # 16 minutes autovacuum_vacuum_threshold = 128 autovacuum_analyze_threshold = 256