ASK NC

Looking to replace current SAN infrastructure (based on Dell R720xD which uses Fusion-io 3.4TB PCIe Gen 2x8 card and 4 SSDs, and 5 x 1TB SATA HDD )

Used to as ISCSI target for Microsoft Hyper-V cluster running 15 VMs of various workloads, mostly no much.
CIFS Storage for all users and other data
Raid 5 ( 1TB disks) for backups of all the above

Nodes and R720 have dual 10GBe with iWarp RDMA over Chelsio NICs

Main drivers are:
better IOPS (thinking M2 NVME), but equally important is to lower the power usage!
Kit is old now, 12 years

Prefer buying a solution like QNAP, but if only way to make affordable is to do DIY, then will

Apart from which hw to purchase, i could do with recommendations on disk layouts to support the two distinct workloads types. i.e. number of each disk type and RAID levels

Many thanks

You could consider TV-464 as budget option or if possible then i5 based TS-674.
In terms of disk layout, it's essential to consider your specific workload requirements and storage capacity needs. For your ISCSI target, I would recommend using RAID 10 with NVMe SSDs, as this provides the best balance of performance and redundancy. You could also consider using a small cache pool of NVMe SSDs to accelerate your ISCSI target further.

For your CIFS storage, you could use a combination of NVMe SSDs and SATA HDDs. One option could be to use RAID 5 with SATA HDDs for your backups, and RAID 6 with NVMe SSDs for your active data. Another option could be to use a hybrid RAID solution, such as QNAP's Qtier technology, which automatically moves frequently accessed data to the faster NVMe SSDs and less accessed data to the SATA HDDs.