db1074 went down:
05:18 <+icinga-wm> PROBLEM - Host db1074 is DOWN: PING CRITICAL - Packet loss = 100%
This caused slave lag on db1125
<+icinga-wm> PROBLEM - MariaDB Slave IO: s2 on db1125 is CRITICAL: CRITICAL slave_io_state Slave_IO_Running: No,
The console showed nothing, so ema powercycled it.
Then jynus depooled it and pointed out this hits tendril which is annoying but does not break wikis.
06:10 <+logmsgbot> !log jynus@deploy1001 Synchronized wmf-config/db-eqiad.php: Mirror dbctl depool of db1074 (duration: 00m 55s)
After the depool we saw recovery of the slave lag alert.