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why the new EVA disk locate at the middle of the enclosure

xing.lucky
Occasional Contributor

why the new EVA disk locate at the middle of the enclosure

I don't know why the new EVA disk locate in the middle of the enclosure ,not insert from the left to right
5 REPLIES
Uwe Zessin
Honored Contributor

Re: why the new EVA disk locate at the middle of the enclosure

It is for physical load balancing. Additional disk drives are then added to the right and left side.
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Matt Burgess
Frequent Advisor

Re: why the new EVA disk locate at the middle of the enclosure

The previous post is correct, but to explain a little further:

It relates to the back-end cabling configuration. The enclosures are considered 'dual channel' just like some scsi enclosures. One i/o module can talk to bays 1-7 and the other can talk to 8-14. This reduces the latency of talking to the disks in the FCAL environment.
Uwe Zessin
Honored Contributor

Re: why the new EVA disk locate at the middle of the enclosure

Interesting. When I look into Command View EVA, I see that all disk drives have AL_PAs on both FC ports and I see consecutive loop positions.

That fits well with what I have learned: the "A" I/O module talks to the "A" FC port of *all* 14 disk drives and the "B" I/O module talks to the "B" ports.

If an I/O module could only talk to half of the bays in an enclosure, there were no redundancy between a dual-loop (A/B).
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Bernd Miess
Occasional Visitor

Re: why the new EVA disk locate at the middle of the enclosure

Another idea: Better cooling performance.
Drives in the middle can be equally cooled by both blowers -> lower overall temperature -> lower RMP

Mark Poeschl_2
Honored Contributor

Re: why the new EVA disk locate at the middle of the enclosure

I had one HP storage engineer tell me it was for weight and balance during the shipping process only. The first thing he did was to move them from the center to left-to-right.