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Performance difference on VNX5400 connecting with 10GbaseT vs SFP
I'm going to connect my brand new VMware servers through iSCSI (using Cisco Nexus 3064-32T) switch using 10Gbit. But I want to take the best route performance wise. Not based upon personal opinions.
However I cannot find any good performance test comparing the two options. Anyone got any experience with either, and have some hard facts like performance measurements or something that is actual proof of differences in speed.
I'm about to place the order with EMC, but I do want to know the differences in speed to make my decision.
So these are the two IO options I'm considering
* 2 port 10Gb/s Opt iSCSI Module with TOE
* 2 port 10 GBase-T iSCSI Module with TOE
Thanks
storagtetalk
53 Posts
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August 27th, 2015 21:00
I can't say that I've tested throughput of optical 10Gb ISCSI vs 10GBase-T. I can tell you there's a documented difference in latency - 10GBaseT has greater latency. But that's measured in microseconds, something around 2us.
I would offer that there are other considerations that may be more important than that difference. What I have tested, is 8Gb FC vs 10Gb ISCSI, and Fibre Channel appeared to have lower latency, measured at the host level. I say appeared, because there are a lot of variables to consider, and I wasn't exactly sniffing packets on the wire. However, Fibre Channel would probably be a more expensive option for you, which may be why you have chosen ISCSI.
Going out on a limb - I doubt you find anyone who can give you a convincing report on the real world impact the extra latency 10GBaseT imposes over optical.
kelleg
4.5K Posts
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September 2nd, 2015 12:00
Are you asking about the interface on the array or on the hosts?
As far as I know we have not done any testing comparing the performance on the array between the Optical and the BaseT interfaces. As the previous note states, copper will be a bit slow than optical cable, but the distances involved are normally pretty short.
I'd recommend that you take a look at the two KB articles on support.emc.com
https://support.emc.com/kb/71615
https://support.emc.com/kb/41172
glen