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I have a DroboPro that is currently connected to a GS748TS switch. Also connected to the switch is a server and few workstations.

Which method would be better in performance?

  1. Add a NIC to the server. Direct connect the DroboPro via iSCSI to the new NIC.

  2. Add a NIC to the server. Create a dedicated VLAN for the new NIC and Drobo.

  3. Add a NIC to the server and attach it to a separate switch. DroboPro connects to the switch. Becomes a private network, similar to a VLAN.

    • DroboPro has a single ethernet connection.
    • Server has a single ethernet connection (currently).
    • Workstations each have a single ethernet connection.
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1 Answer 1

This depends entirely on your infrastructure.

Add a NIC to the server. Direct connect the DroboPro via iSCSI to the new NIC.

This defeats the purpose of iSCSI. Why not just get a DAS if you're going to do this? It would be faster.

Add a NIC to the server. Create a dedicated VLAN for the new NIC and Drobo.

This is fairly common, but you need to make sure your switch's backplane isn't being oversubscribed. If it is, you could have serious performance issues. If you can prioritize storage traffic across the backplane, do it.

Add a NIC to the server and attach it to a separate switch. DroboPro connects to the switch. Becomes a private network, similar to a VLAN.

This is also common. If you have concerns about performance or security on a shared switch, do this.

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1 and 3 are effectively the same if only one initiator exists. I think your question "why not get a DAS" is answered with "so we can add a switch and other initiators later". –  Jed Daniels Nov 8 '12 at 15:45
    
In response to MDMarra... So 8 drives connecting to a single eSATA port would be faster than through iSCSI? Also, how can I tell if the switch isn't being oversubscribed? I believe I can priortize as it is a smart switch. I have to contact Netgear to verify. –  Unplugme71 Nov 8 '12 at 15:52
    
Yes, eSATA will likely outperform iSCSI. If however you need to share this storage with multiple hosts I think your bottleneck will not be the switch backplane unless you're using some pretty crappy gear. At that point you'll be stuck hitting against a single 1Gb connection to your Drobo with multiple initiators. –  SpacemanSpiff Nov 8 '12 at 16:14
    
Physical eSATA throughput is either 1.5Gbps, 3Gbps, or 6Gbps, depending on the hardware at each end. a single iSCSI connection over gigabit Ethernet is 1Gpbs theoretical with about 800Mbps as a more "real world" estimate. You can tell if a switch is oversubscribed by taking the backplane speed, taking all of the port speed, factoring in duplex, and seeing if you're over the backplane rating. For example, if you have 24 GbE ports at full duplex, you're clients could push 48Gbps through that switch if everyhing is at 100%. Very rarely to 24 port switches have backplanes rated at 48Gbps. –  MDMarra Nov 8 '12 at 16:21
    
DroboPro is only connected to the one server. We then share folders for users to map on their workstations. I have another DroboPro for another server, and is replicated using DFS. I basically want data between the two drobo's to be on the private VLAN as well as our third server that runs backups. This way any DFS replication and backups aren't on the same traffic as user data. –  Unplugme71 Nov 8 '12 at 16:22

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