How are the drives used on their SQL server boxes? They have a massive NVMe drive on raid 0 with 20 sata drives in raid 10? Which drives are used for prod data? Do they run backups on the same box?
In the Stack Exchange cluster, the RAID 0 NVMe array contains all databases except for a large log database (which I called Careers.BigStuff, because it seemed like a good idea at the time). This larger log database is much more rarely accessed and is on the 10K HDD RAID10.
We run backups on the primary for several reasons, but they are all sent off-box. We have 2 primary on-site backup servers, then those backups go offsite and to tape. Database backups are every 15 minutes with T-Logs and full backups nightly. We also run copy-only backups in the DR data center nightly as an additional backup measure.