We've definitely been over these docs, with and without their support team. We are well below the caps on the both the disks and the VM size in use.
Sorry, i just want to use all the info, i have less exp :)
do you generate large wals ?
Our WALs are standard 16MB in size.
if your checkpoint_completion_target is aggressive, it will result in a lot of io.
if the checkpoint is spread over a larger time window, maybe it will reduce frequent i/o pressure.
but for that log_checkpoints needs to be turned on if they are hogging the iops.
checkpoint_timeout is 5min, max_wal_size is 5GB. The vast majority of checkpoints are time-initiated, not wal-initiated. We've tuned this in the past. Over the past 16 hours there have been only 5 checkpoints started due to wal pressure. There was no such wal-initiated checkpoint that corresponds to the most recent WALWriteLock spike either.