I'm hosting my own Lemmy instance and trying to figure out how to optimize PSQL to reduce disk IO at the expense of memory.

I accept increased risk this introduces, but need to figure out parameters that will allow a server with a ton of RAM and reliable power to operate without constantly sitting with 20% iowait.

Current settings:
# DB Version: 15
# OS Type: linux
# DB Type: web
# Total Memory (RAM): 32 GB
# CPUs num: 8
# Data Storage: hdd

max_connections = 200
shared_buffers = 8GB
effective_cache_size = 24GB
maintenance_work_mem = 2GB
checkpoint_completion_target = 0.9
wal_buffers = 16MB
default_statistics_target = 100
random_page_cost = 4
effective_io_concurrency = 2
work_mem = 10485kB
min_wal_size = 1GB
max_wal_size = 4GB
max_worker_processes = 8
max_parallel_workers_per_gather = 4
max_parallel_workers = 8
max_parallel_maintenance_workers = 4
fsync = off
synchronous_commit = off
wal_writer_delay = 800
wal_buffers = 64MB
Most load comes from LCS script seeding content and not actual users.

Solution: My issue turned out to be really banal - Lemmy's PostgreSQL container was pointing at default location for config file (/var/lib/postgresql/data/postgresql.conf) and not at the location where I actually mounted custom config file for the server (/etc/postgresql.conf). Everything is working as expected after I updated docker-compose.yaml file to point PostgreSQL to correct config file. Thanks @bahmanm@lemmy.ml for pointing me in the right direction!

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[–] daq@lemmy.daqfx.com 1 points 1 year ago

If you like, you can give me access to the Grafana dashboard so I can take a look and we can take it from there. It's going to be totally free of charge of course as I am quite interested in your problem: it's both a challenge for me and helping a fellow Lemmy user. The only thing I ask is that we report back the results and solution here so that others can benefit from the work.

No problem. PM me an IP (v4 or v6) or an email address (disposable is fine) and I'll reply with a link to access Grafana with above in allow list.