Redis by default saves its data to disk every 5 minutes (default configuration).
This results in writing ≈11 MB to disk + fsync + fdatasync, which given the modern file systems write amplification is about 5-6 GB/day.
Does Redis need to save its data to disk at all?
As far as I understand, it’s used only as a temporary storage for logs, and for rspamd temporary (cached) spam classification data.
If Redis needs it, please consider increasing the state saves up to 30-60 minutes or so. Redis also allows to configure saving only if X keys has changed.
Right now it uses (from CONFIG GET * of the running instance):
"save"
"3600 1 300 100 60 10000"
Which corresponds to, as SAVE documentation says:
Save every hour if at least 1 key is changed,
Save every 5 minutes if at least 100 keys are changed
Save every minute if at least 10000 keys are changed
If Redis does NOT need it, please just disable it:
Add the following to mailcow/mailcow-dockerizedblob/489db905122d20487e29c9a8438b311c403442ab/data/conf/redis/redis-conf.sh
save ""