A9nWGzYt

Well, here I have 41 containers and:

free -hm
               total        used        free      shared  buff/cache   available
Mem:            31Gi       5.7Gi       426Mi       207Mi        25Gi        25Gi
Swap:           31Gi       3.7Gi        28Gi

As well as

cat /proc/sys/vm/swappiness: 10

and

$ cat /proc/pressure/cpu
some avg10=0.00 avg60=0.00 avg300=0.00 total=302436406
full avg10=0.00 avg60=0.00 avg300=0.00 total=0

$ cat /proc/pressure/memory
some avg10=0.00 avg60=0.00 avg300=0.00 total=64263542
full avg10=0.00 avg60=0.00 avg300=0.00 total=63043120

$ cat /proc/pressure/io
some avg10=1.99 avg60=1.67 avg300=1.61 total=1844790000
full avg10=1.90 avg60=1.59 avg300=1.56 total=1788451770

I agree with you that my server specs are a little bit excessive for my usual workload. I have disabled swap in the past with swapoff -a and removed the partition from /etc/fstab under a similar usage, and no issues were observed.

I am just leaving it there now for the rare instance when I run the occasional lightweight local LLM model (on CPU) for light tasks such as spell checking, which might need some RAM and I don’t risk crashing due to OOM issues.

However, I still want to understand what is happening here to learn a little bit about my system. My intuition can be wrong here, but I find it strange that my laptop with similar specs and the same OS (but reasonably distinct workloads, to be fair) almost never swaps nor reaches those ridiculous levels of buffer + cache usage, so I think I might find one “offender” container to blame.

Thanks for the tip. I have been looking into commenting out the ollama portion of the docker-compose.yml file and setting up llama.cpp instead for some time now. I suspect I don’t usually use features such as ollama pull to justify a fully-featured application.

Why is my home server using so much RAM for cache + buffer?

I have noticed that my home server is strangely using lots of swap (~5 GB), despite having only a few lightweight processes running and loads of RAM installed (32 GB).

Upon configuring Grafana + Prometheus, I noticed a trend where cache + buffer will progressively increase until swap starts to be used. My system and services combined will use ~8 GB RAM. Upon rebooting, the cache + buffer will start anywhere from 3–10 GB, progressively ramp up to ~25 GB in 1–2h, where swap will start to be needed (~3 GB). See the image attached for reference.

My swap filesystem is on an expensive (to me) SSD, and I would like to reduce its wear by as much as possible. I understand that swap can introduce only minimal wear on SSDs depending on its nature and that it can be harmless, but I am still not sure what is causing this behavior (and why) and whether I should worry about it or not. So I figured I should investigate what is happening here.

My main question is, how can I figure out what is causing this behavior? Is it expected? I am looking for guidance from others who are more experienced than me in the topic.

A little bit about my system:

I am running Debian 12 on an NVMe SSD containing the root partition (btrfs) and docker services. I also have two HDDs, one with persistent data (ext4), and the other with backups (ext4). This is majoritarily a single-user machine. I tried using the following kernel parameters, but it hasn’t helped:

vm.swappiness=10
vm.vfs_cache_pressure=200

My docker services are:

• *arr stack
• jellyfin
• nextcloud
• immich
• open-webui + ollama
• pi-hole
• invidious
• romm
• nginx proxy manager
• grafana + prometheus
• other minor services that I don’t think are doing much (uptime-kuma, stirlingpdf, vaultwarden, etc)