[Info-vax] ES47 2G FC and rx2800 i4 8G FC in same VMS Cluster with Shadowsets on shared storage controller? Is this possible?

[Grant Taylor]

On 3/12/20 6:44 PM, Jon Pinkley wrote:
> We currently have a cluster of two ES47s with 2G FC and an EVA6000 with 
> 4G FC and 4G FC switches (StorageWorks 4/32B, HP relabeled Brocade)
> 
> We want to migrate to Itanium rx2800 i4 or i6 servers and a shared 
> FC storage controller (perhaps 3PAR 8200?).  HPE said that the 3PAR 
> has 16G FC and they were not very optimistic about us being able to 
> use it with the ES47's.  They said that FC could go up/down 2 speeds, 
> but others have said only 1.

The two (or one) speed steps surprise me.

Is that limitation the 3PAR?

Will you be connecting it to a new 16 G FC switch?  What speeds will it 
support?

> I also don't know if FibreChannel forces two communicating devices 
> to negociated at the same speed, or if it is like a store/forward 
> Ethernet switch and negociates each link at the lowest speed.

What speed is your EVA6000 linked to your FC switches at?

What speed are your ES47s linked to your FC switches at?

I bet the answers are 4G and 2G respectively.  Thus you are already 
using a switch to do a speed conversion.

> In other words, we currently have 4G switches, 4G EVA controller, 
> and 2G ES47.  Does the FC link between the 4G switch and the 4G EVA 
> operate at 4G and the link between the 4G switch and 2G ES47s operate 
> at 2G, and the switch does store and forward speed conversion like 
> most ethernet switches do?

That would be my expectation.

> Any pointers to useful documentation would also be appreciated.

I would also expect that you can find out the link speed from all of the 
devices in question.

16G -> 8G -> 4G sounds like it will link to your existing FC switch.

I would expect that you will be getting a newer 16G FC switch.  Can you 
link it to your existing 4G FC switch?

Presuming that you can, I'd expect speeds like the following:

+------+
| ES47 +--2--+
+------+     |
              |
          +---+---+     +--------+      +------+
          | 4G FC +--4--+ 16G FC +--16--+ 3PAR |
          +---+---+     +--------+      +------+
              |
  +-----+     |
  | EVA +--4--+
  +-----+

Attach the rx2800s to the 16G FC switch.  So the link between the 4G & 
16G switch is the only link between old and new, and it's temporary 
during the transition.

My biggest concern would be the difference in performance between the 
ES47s connected at 2G and the rx2800s connected at 16G (?) causing some 
sort of heartburn for the clustering.  But I would expect the FC to 
handle this gracefully.

I may be completely off my rocker.  But that's what I would expect.



-- 
Grant. . . .
unix || die