Topic
Quorum, sharding, failover and backup across MongoDB, ScyllaDB, Redis, MariaDB/Galera and Solr — measured on a rig rather than quoted from a docs page.
Every distributed database advertises high availability, and the claim is usually true in a sense that will not help you at two in the morning. So I built a rig — MongoDB, ScyllaDB, SolrCloud, MariaDB with Galera, Redis in both Cluster and Sentinel modes, and PostgreSQL — and killed the primary in each while measuring what actually happened and how long it took. 8 of 8 failover scenarios passed; Redis Sentinel promoted a replica to writable in ~5 s. Everything in this topic is a number from that rig, published with the test plan attached so you can reproduce it or disagree with it.
Build Trino 483 on Iceberg with Apache Polaris as the REST catalog, then prove the vended S3 credentials cannot read the table next door.
~45 min to a working stack; the credential-vending section is the part that takes the time
Wire pgBackRest into a running Patroni cluster over mutual TLS with Ansible, then prove it: full backup, replica rebuilt from the repo, and a point-in-time restore.
~90 min on an existing cluster; the restore drill itself is ~15 min
Build a two-node Patroni cluster on Rocky 8 under QEMU, then SIGKILL the leader and measure the promotion, the timeline bump, and the pg_rewind rejoin.
~2–3 h first bring-up (TCG is slow); ~5 min for the failover itself
Three ScyllaDB behaviors that make a perfectly valid snapshot restore return zero rows, with the repro, the fix, and the AIO limit that stops node three.
~40 min hands-on
Six database engines, eight failover scenarios, one 8-CPU Docker rig. The results matrix, the headline measurements, and how to run the first scenario.
~45 min hands-on