McGarrah Technical Blog

Posts in category "ceph"

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.