> A similar "tuning best practice" that I still see applied in the field is database servers with dedicated data, log, temp, and templog drives... on cloud VMs

> A similar "tuning best practice" that I still see applied in the field is database servers with dedicated data, log, temp, and templog drives... on cloud VMs where this is guaranteed to have worse performance than simply pooling the same amount of disk into a single logical drive. It's not guaranteed to be worse. For latency sensitive OLTP workloads dedicated, smaller, disks for the journal can result in substantially lower & predictable latency. Random reads for the data exhausting iops, causing stalls of journal writes isn't fun. There's also per-disk queuing on a bunch of levels, and avoiding intermingling data and journal writes can be quite beneficial. That's not to say it's always better, at all. But making it out to be a stupid thing one should never do isn't wise either.