Magento2.4.2 : redis RAM full only on prod infra

Hello ! I’m facing something strange that I’m trying to understand.. I got 2 infras (one for test and one for prod) and they have both ~20K products. I use redis + varnish for caching and I don’t understand why my prod redis (having a max size of 16 GB) is ALWAYS full using the 16GB while my test redis (same version, same config, same products….) is using something like 100M opposite of the 16GB used by the prod one… Do you have any explanation / suggestion ?

Interesting fact : when I’m flushing the html block cache, the RAM goes back to almost zero, before going up to 16Gb.. so it’s full of HTML blocks only on prod and I still don’t know why :/

here’s my redis configuration :

# User-supplied common configuration:

# DISABLE AOF https://redis.io/topics/persistence#append-only-file

# appendonly yes

# auto-aof-rewrite-percentage 100

# auto-aof-rewrite-min-size 64mb

# ENABLE RDB persistence, AOF persistence already enabled.

save 900 1

save 300 10

save 86400 1

# save ""

maxmemory 16gb

maxmemory-policy volatile-lru

maxmemory-samples 20

#lazyfree-lazy-eviction yes

lazyfree-lazy-expire yes

lazyfree-lazy-server-del yes

replica-lazy-flush yes

lazyfree-lazy-user-del yes

# End of common configuration

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Thanks for now 🙂