iSCSI switch replacement (2 VMware hosts)

Question

Good morning everyone, I recently bought two unmanaged NetGear 1gb switches to replace our older unmanaged Cisco 1gb iSCSI switches. Right now, the only devices currently connected to this network are 2 VMware 5.5 hosts and a Dell 3220i SAN.

Last week I attempted to cut over by moving just a single connection at a time. Essentially, I moved one SAN iSCSI connection over to one of the new switches, then one from each of the hosts and then rescanned the bus, hoping that it would find the new route on its own, which is turn would allow for no down time at all. Well, this didn't happen. Bassically when I moved them over and rescanned the bus, the old routes just disappeared and I was left with the remaining routes on the old switches, but when I gave up, plugged them back into the old switches and rescanned the bus, they re-appeared.

Can anyone tell me why the hosts failed to pick up the new physical connections through the new switches? Do I need to just shut everything off and swap them over?

FYI, the network subnetting did not change.

Let me know if you need more information.

Did you replicate the same VLAN structures on the new switches as they were on the older ones? — Chopper3, Aug 03 '15 at 13:44
Yes, nothing changed on the NIC settings/VSwitches and since the physical switches are unmanaged, nothing to change on them either. — HondaKillrsx, Aug 03 '15 at 14:03
The storage and the hosts connect directly to these switches? There aren't any intermediate switches or routers? — joeqwerty, Aug 03 '15 at 18:11
Boy, I really want to say that this has something to do with the MAC address table on the new switch but I'm hesitant about that being the cause of the problem. I'd suggest firing up Wireshark or the like on one of the hosts and running a capture when trying this again. — joeqwerty, Aug 07 '15 at 03:40

score 0 · Accepted Answer · answered Mar 08 '16 at 15:37

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Just so everyone knows, the answer to my problem was the subnetting. It appears that when doing this type of cut over, you can not use the same subnetting as the old network. I completely changed the subnetting from 10.11.12.0 to 192.168.1.0 and they showed up without issue.

answered Mar 08 '16 at 15:37

HondaKillrsx

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So basic IP skills then... – Chopper3 Mar 08 '16 at 15:44
No, when have you ever needed to configure a different subnet for each additional unmanaged switch? That would be a nightmare on your normal network. not to mention the amount of router configuration to get the subnets to talk to one another. @Chopper3 – HondaKillrsx Mar 08 '16 at 17:05

iSCSI switch replacement (2 VMware hosts)

1 Answers1