Redis Cluster - Redis Using to much RAM Memory

Redis administration
1

Hello!
I’ve set up a Redis cluster with 6 nodes(3 M + 3 R). I allocated to the VMs 128 GB RAM with a Redis maxmemory of 70 GB.

No matter what limit I set, Redis is using all the memory up to that limit. I’ve started with 22GB and increased it to 48GB, 70GB, and even 110GB. The Storm topologies that are sending the data to Redis are not failing, were working fine even when the maxmemory was 22GB.

It seems to me that Redis doesn’t actually need all this memory but for some reason(config configurations) it is using all the memory allocated.

The dump.rdb size is 14GB on all three master nodes.

Thank you!

2

How did he conclude it uses all the memory?
Redis info or ps , is it vmsize or real usage?
Did evictions or OOM errors happen?

Our guess is that these are client output buffers.

1 Like
3

Hello Guy! Thank you for taking the time to answer.
Here is the output of redis-cli info memory:

Redis-Cluster-Memory
Redis-Cluster-Memory323×830 17.3 KB

The redis.evicted.clients metric is 0 on all the 6 nodes and I didn’t see any OOM in the logs.

Another issue that I’ve encountered was that the Replicas kept on disconnecting from the Master Nodes.
I had to go as high as — client-output-buffer-limit replica 25000mb 12000mb 320 — to stop this behavior.

Is it a mistake to keep permanently the client-output-buffer-limit to such a high value?
For now, I’ve allocated 96GB to the VM with 48GB maxmemory, and on the VMs there is about 25GB free RAM.

Any advice is much appreciated.

Thanks again!