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I work for a small state college. We currently have 4 ESXi hosts (all made by Dell), 2 EqualLogic SANs (PS4000 and PS4100) and a bunch of old HP Procurve switches. The current setup is very far from being redundant and fast so we want to improve it. I read several threads but get even more confused.

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The Procurve Switches are 2824. I know they don't support Jumbo Frames and Flow Control at the same time, but we have plans to upgrade to something like Procurve 3500yl. Any suggestions? I heard Dell Powerconnects 6xxx are pretty good but I'm not sure how they compare to HPs.

There will be a 4-port Etherchannel (Link Aggregation) between the switches, and all control modules on SAN will be connected to different switches.

Is there anything that will make the setup better? Are there better switches then Procurves 3500yl that cost less than 5k? What kind of bandwidth can I expect between ESXi hosts (they will also be connected to 2824 with multiple cables) and SANs?

Basil
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Sergey
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2 Answers2

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On the note between jumbo frames and flow control: if you have to choose between them, remember that flow control only benefits you when you are saturating an ethernet link in the data path. iSCSI traffic's flow control natively is dropped packets, and unfortunately the underlying SCSI stack can't handle that well. It results in multi-second read latency. So while jumbo frames will always benefit you, when you're pushing your storage to its limit, flow control will benefit you more.

Basil
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You've made it about as redundant as you can given the current hardware on hand. Some thoughts:

Of course make sure that each ESXi host is connected to both switches.

  • You need to use "per port load balancing" on the ESXi side and "adaptive load balancing" or whatever they call it on the Equallogic side if you want to handle redundancy at the Ethernet layer. You cannot use LACP or any other form of channel-bonding, as the switches are totally independent and do not support MLAG.

  • If you do not configure iSCSI multi-pathing on both ESXi and EqualLogic sides, you will be limited to 1 GBps throughput to each ESXi host. Using network-layer redundancy is simple to confiugre, but it comes at a price.

  • Make sure you have rapid spanning tree enabled, with one switch configured as root primary, the other as root secondary. BPDU guard or similar on the all ports except the trunk between switches to avoid meltdowns.

rmalayter
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