I have 3 mariadb galera db's, 2 nginx/php machines at these sizes DBs - E8ds_v5, nginx/php-fpm - D4ds_V5 I am getting really bad performance from mariadb. These machines are in the same vnet, but different subnets for db and web. The two nginx/php-fpm servers share web files through and azure files premium nfs share which seems to be working OK.
I have tried upgrading the storage of the DBs to P40 with no change in performance. Currently testing with an upgraded instance size(only one server to test) to E20ds_v5, Storage at Premium SSDv2 (30,000 IOPS, 500 MB/s)
I am running wordpress benchmarks and timing db queries to a barebones wordpress install with absolutely no change in score no matter what is done. The barebones wordpress install is pointed directly to the upgraded machine at the moment. My next step is to try and use MySQL Flex, but it would be great if I could get this self hosted mariadb working.. no matter what amount of tuning is done, things seem to remain the same, slow.
I think the biggest problem is that I get terrible performance if MySQL is not running locally to where PHP is being processed.
Here are the benchmark scores from Wordpress Hosting Benchmark tool with different setups.
Benchmark of nginx/php-fpm/mariadb on the same VM (Standard_D1_v2) - NODATA
Benchmark of nginx/php-fpm/mariadb on the same VM (Standard_D1_v2) - WITH DATA
When using 2 NGINX/PHP-FPM servers with 1 maria db (same subnet) mentioned above NO DATA
The problem turned out to be the slow Azure Files NFS system. Even though it was a Premium(Hot) NFS 4.1 fileshare, it was too slow.
We built our own HA NFS server and haven't had problems with the DB anymore.