cross-posted from: https://lemmy.daqfx.com/post/24701

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!

  • towerful@programming.dev
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    1 year ago

    Your Prom PG Exporter is a 404 (I think there is a trailing t in the URL).

    Do you have any recommendations for dashboard for grafana/Pg?
    As well as statistics that are important?
    This is something I’m going to be putting into my deployment, and it’s really easy to get overwhelmed with data!

    • bahmanm
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      1 year ago

      Oh, updated the link 🤦‍♂️

      The stock Grafana dashboard for PG is a good starting point. At least, that’s how I started. You really should add new metrics to your dashboard if you really need them as you said.

      Don’t forget to install node-exporter too. It gives some important bits of info about the PG host. Again the stock dashboard is a decent one to start w/.