How many host per FA port?

Hi llello,

take a look at interop matrix and search for "fc-fanout"

http://www.emc.com/collateral/elab/emc-support-matrices.pdf

Thanks, but there is no written connection between IOPS (port speed) and number of hosts.

take a look at this discussion

https://forums.emc.com/forums/thread.jspa?messageID=691467򨴋

I'm guessing the answer is 5. The storage array does a max of 6k iops for a single port, if every host does 1.2k iops your aggregate iops peaks at 5 hosts. i.e. 5 hosts * 1200 iops/host == 6000 max iops the port supports. If you had a sixth host you have gone past the ports limit on the number of iops (7200)

Not sure it really means anything in real life, as workloads tend to be more random and vary per host.

Unfortunately the answer should be "3", but I don't know why, and I am looking for this answer 3 weeks already....:(

I guess it's simply a queuing problem.
It's a quite complex and interesting field.

http://en.wikipedia.org/wiki/Queueing_theory

To make a long story short, if a system can "handle" N operations per second, the response time won't grow proportionally to iops (since the requests from hosts follow a random pattern). And usually it tends to "diverge" (grow very fast) if you reach 60/70% of utilization. That's what usually we call "the knee".

Now guess what's 60/70% of 5

If you google a little you can find a lot more details on this .. Try googling for "queue theorie response time".

Here's an couple of examples:

http://www.cmg.org/measureit/issues/mit60/m_60_9.html

http://ramya-moorthy.blogspot.com/2008/03/response-time-vs-queue-length-vs-server.html

Thanks a lot.
Now I remember,that in some EMC Clariion documents it is written, that everything in the system should be utilized no more than 70%.
This is the best possible answer.
Thanks again

I'm pretty glad it solved your clue
However considere (as you can see in the links I posted) that it isn't related only to clariion or storage. It's a general rule that applies everywhere you have a "server" (a generic term referring to something/someone serving requests) and its clients

Has your question been answered?

Message was edited by:
KCSCP

Yes thank you.

I guess KCSCP simply wanted to remind you that you should mark the question as "answered" and eventually award points (green/yellow stars) to better/good answers you received..