Does LINBIT SDS support monitoring?

Yes, LINBIT SDS (LINSTOR) exposes a Prometheus metric endpoint on the controller, which can report on storage-pool utilization, resource definition counts, node states, etc.  DRBD, the replication used in LINBIT SDS, also supports exposing Prometheus metrics.

Does LINBIT SDS architecture support multiple performance classes?

Yes, you can have multiple storage classes defined within LINSTOR. Each storage class could be backed by different classes of physical storage. Larger slower SSDs could make up one LINSTOR storage pool, while smaller lower latency NVMe devices could be used as another storage pool.