Measuring the WAL vs DB Performance Gap on Ceph USB OSDs
Nine of my fifteen Ceph OSDs use WAL-only acceleration while six use DB. I set out to measure the performance gap and discovered the real story isn't WAL vs DB — it's the USB 3.0 hardware ceiling that dominates everything. The matched-hardware comparison shows DB is 5-15% faster on reads, not the 32% that naive cross-node testing suggested.
Hybrid Ceph Storage: SSD WAL/DB Acceleration with USB Drive Data
Running Ceph on USB drives sounds crazy until you put the WAL and DB on an SSD. Here's how separating metadata onto a Crucial MX500 transformed my 15-OSD homelab cluster from sluggish to surprisingly capable — at a fraction of all-SSD costs.
Thinkpad T480 WWAN SSD
Adding another SSD Drive
In my eternal tinkering with my Lenovo Thinkpad T480s, I have continued the trend of adding new features. So earlier, in A new to me but old laptop and New Laptop update, I threw out a bunch of enhancement options. Some of those I’ve done and some I left on the backlog as things that just cost too much on my metric of usefulness per dollar. The WWAN SSD for extra storage was one of those that just seemed like a bad bang-for-the-buck for storage. I also like the option to add a SIM card and have cellular network available in case I have to go back to consulting on the road.