A server that is part of a SQL 2017 Always on availability group (BAG) I have noticed an increase of these messages. I understand these are messages that appear in the log as standard since 2012 (trace flag prior to 2012) but over the last 2 days they are appearing every few minutes, there are no backups running or maintenance jobs at these times
The server is acting as the secondary non readable fail over partner and the primary server is not exhibiting the same behavior.
09/04/2020 10:52:24,spid82s,Unknown,FlushCache: cleaned up 2303 bufs with 1881 writes in 81090 ms (avoided 11 new dirty bufs) for db 7:0 09/04/2020 10:52:07,spid52s,Unknown,last target outstanding: 2 avgWriteLatency 86 09/04/2020 10:52:07,spid52s,Unknown,average writes per second: 17.70 writes/sec average throughput: 0.19 MB/sec I/O saturation: 13073 context switches 15434
There is also a warning in the system error log about disk issue, seconds after this the availability group failed over ever since the FlushCache messages have increased.
Has anyone experienced anything similar or have any advice, my sysadmin is also looking at the SAN and VMware estate.
Had a sudden thought could these be caused by autogrowth activities?