What hard disk you plan ?. Let it be SAS Enterprise Disk. Also don't configure RAID 5, and has huge write impact, which of course affect multiple VMs running. Try RAID 10 or possible 60.

Any Enterpirse disks with RAID10 supports iSCSI and NFS storage is a good candidate for VMWare.

You want to consider usage, capacity, protection level and connectivity.  When you work out your capacity, double it just for future purposes

I personally use Synology but QNAP are equally as reputable.  I like the fact the Synology has hardware acceleration, not sure the QNAP does (but i don't know).

agree that Synology and QNAP are equally..

QNAP provide VAAI support

QNAP Plugin for VMWare vStorage API for Array Integration (VAAI) - QNAP

https://files.qnap.com/news/pressresource/datasheet/QNAP_Plugin_for_VMWare_vStorage_API_for_Array_Integration_(VAAI)(Eng…

Hi,

few questions:

- how will be the NAS connected -1gig/10gig ?

- how busy are these 10-15VM's?

- what disks do you want to use?

- will be there any SSD/NVMe cache

- which model?

- it will be for production VM's or for LAB?

Thanks

Qnap is better - it have lots more configuration and monitoring features than Synology. Yes, iSCSI is always slower by latency than internal SSD. You must use ESXi "Virtual Flash Read Cache", to set it for every virtual disk separately (how much it can use read cache). It compensates latency. Also best should be 10 Gbit nic. I have example 4-bay Qnap TS-453B. It allows to separately purchase special 10 GBit PCIe x4 nic, for 1 port or 2 port. RAID 5 is ok, dont fear it. 4nd disc in Qnap must be SSD cache for speed. Put all VM virtual disks into the same LUN and make them dependent. The best in iSCSI SAN is possibility to make backups very fast, online and absolute point in time together with running memory. When you make VM snapshot with memory, memory dump stay in the same LUN (VM configuration must be also in the same LUN). Then you make Qnap LUN snapshot and then backup-replicate it to second Qnap. Its very fast, incremental and changed block tracking. Then you can delete both Qnap LUN snapshot and VM snapshot.  For second Qnap I have cheaper one, 2-bay in raid0. But it must be little bigger in space, as LUN snapshots backups, if you want to show its content, must first copied to somewhere. Qnap have also lots of automatic and shedulings and also vSphere Spanshot Agent for vCenter.........And of course, ESXi itself dont allow RAID at all, with Qnap you can have RAID. ESXi dont have software raid, hardware raid cards must be only in compatibility list. This means you must forget all half software-hardware mainstream raid cards for ESX, but real hardware cards cost much more than Qnap and have less features.