Technical Blog

Ceph Cluster rebalance issue

This is rough draft that I’m just pushing out as it might be useful to someone not stay in my drafts folder forever… Good enough beats Perfect that never ships everytime.

I think I have mentioned my ProxMox/Ceph combo cluster in an earlier post. A quick summary is it consists of a five (5) node cluster for ProxMox HA and three of those nodes have Ceph with three (3) OSDs each for a total of nine (9) 5Tb OSDs. They are in a 3/2 ceph configuration with three copies of each piece of data allowing for running if two nodes are active. Those OSD / hard drives have been added in batches of three (3) with one added on each node as I could get drives cleaned and available. So I added them piece meal in a sets of three OSDs, then three more and finally the last batch of three. I’m also committing the sin of not using 10Gbps SAN networking for the Ceph cluster and using 1Gbps so performance is impacted.

Adding them in pieces as I also loaded up the CephFS with media content is what is hurting me now. My first three OSDs that are spread across the three nodes are pretty full at 75-85% and as I added the next batches, the cluster has never fully caught up and rebalanced the initial contents. This impacts the results of my ‘ceph osd df tree’ results showing I have less space then I actually have available.

Something that I’m navigating is Ceph will go into read-only mode when you approach the fill limits which is typically 95% of space available. It starts alerting like crazy at 85% filled with warning of dire things coming. Notice in my OSD status below that I have massive imbalances between the initial OSDs 0,1,2 versus 3,4,5 and 6,7,8.

Ceph OSD Status

Aggregated Network Connections with LAG/LACP

This is a meandering post without an immediate happy outcome.

I am working on a five node ProxMox 8.1 cluster with three nodes as a Ceph cluster to host my media collection. I’m learning a bunch about Ceph and Proxmox which I’ll post about later. The media collection I am importing into Ceph is a little over 16Tb from ripping my VHS, DVD, BluRay collections of movies and tv shows. Movies end up being less than a third of that content.

New Laptop update

My new to me Thinkpad T480 is doing great. The better processor and the upgraded Nvidia MX150 GPU are both getting a workout with several of the new LLM models. I maxed out the RAM, Wifi, Hard Drive, and swapped around adding all the best components/features to one laptop consolidated from several different junkers I purchased. Those components include IR Camera, WWAN, backlit keyboard, good batteries, and a nice case.

A new to me but old laptop

I’ve been using an older Lenovo Thinkpad T460p laptop that I bought brand new May 2017 for $2210 USD with a pretty impressive discount for the time. The Thinkpad T460p released April 2016 over a year earlier from when I bought it. I over bought on the CPU/processor and bought extra power adapters and batteries upfront. It has been a great laptop but starting to show its age and I’ve been looking for a new laptop with a little more pep. Older USB is starting to be limiting and I’d like to go beyond 32Gb RAM.