I'm using a NAS box as a datastore for my esxi host. The NAS and esxi host are connected to each other via a switch.

I want to experiment a little and was thinking of ways to connect the NAS box to the host directly, and was wandering if it even possible and what effect(s) it will have

(1) if the NAS box and esxi host have another, spare ethernet port, can I connect them to each other directly? Instead of through a network? Would this have much of a performance gain?

(2) USB 3.0. Can I connect the NAS box to the esxi via usb 3.0 cables so that the NAS appears as a mass storage device? Given the performance of USB 3.0, would this be beneficial?


This depends on your NAS unit. You can attach the NAS as a datastore either via NFS or preferably iSCSI if that is a supported option.

Whether connecting them directly has a performance benefit depends on your network topology and how much traffic your VMs produce. If your VMs do not produce too much traffic and both the hypervisor and the NAS are attached to the same switch, the performance gain would be rather small. But if both units have a spare port anyway, there isn't really a reason not to.

Using USB as a datastore is not supported in ESXi, so I wouldn't do it. But it is possible and might be faster again depending on the exact hardware of both machines.

Another solution would be to connect both machines via 10 GbE or eSATA. eSATA is also not officially supported but it is better than USB.

  • Ah yes I think I have an eSATA port on both! Thanks. – Umair Nov 23 '16 at 15:13

1) Yes. Performance gain due to eliminating the switch: Effectively zero. It still can help (potentially a lot) if the other network port has other traffic on it, as the direct connection is exclusive for the NAS traffic.

2) As far as you are asking if you can use USB block storage to format it with VMFS: Effectively no. It's still not official supported to my knowledge, and while there exist posts on the internet that explain how to do it anyway, I believe this is bad practice.

  1. Yes, it will work. The performance will will be negligible, unless your switch is completely overloaded or super duper crappy.

  2. Possible, yet. Supported, no. You will have to test to see if it's faster.

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