Re: CPU performance impact of Fibre Channel Adapters (100 Views)
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Trusted Contributor
Fred Metcalf
Posts: 233
Registered: ‎12-02-1996
Message 1 of 4 (100 Views)
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CPU performance impact of Fibre Channel Adapters

Given: An N4000-400-750 with 4 existing A6795A PCI 2GB Fibre Channel Adapters, each adapter configured with 16 x 29.3GB LUNs; and the CPU time I notice in Glance spent on IO for each Adapter. What is the best way, for optimum CPU performance, to add another 16 x 29.3GB LUNs?
A. Add 4 new LUNs to each of the existing Adapters.
B. Add all 16 new LUNs on a 5th Adapter?
C. Split the 16 new LUNs equally over a 5th and a 6th Adapter?

Thanks
Fred
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Honored Contributor
Kwan Fong, Emile
Posts: 1,162
Registered: ‎07-10-2000
Message 2 of 4 (100 Views)

Re: CPU performance impact of Fibre Channel Adapters

Hello Fred,

#B would be the preferred choice. 16 Luns per FC is the suggested maximum.

#A could be an option depending on the storage array; some newer storage arrays like XP1024/XP128 have their FC interface supporting 2Gbit per second throughput.

There is a very good article on Disk performance right here: http://jazz.external.hp.com/mpeha/papers/off_white_2004.html
King is the customer!
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Trusted Contributor
Fred Metcalf
Posts: 233
Registered: ‎12-02-1996
Message 3 of 4 (100 Views)

Re: CPU performance impact of Fibre Channel Adapters

Thank you Emile.
I should have mentioned the storage is an XP10000. Fred
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Honored Contributor
Kwan Fong, Emile
Posts: 1,162
Registered: ‎07-10-2000
Message 4 of 4 (100 Views)

Re: CPU performance impact of Fibre Channel Adapters

Hello Fred,

In theory, the more pathways (in this case, FC adapters) to datas you have, the better is the system performance.

I've seen some customers who use more than 16 LUNs per card and that does not seem to be an issue.

With the XP10000, you may want to try with option #A and monitor.

Note: Although adding extra FC card increases the number of "pathways to datas", be aware FC card management uses CPU cycles.
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