Hi all, maybe some of you would have some experience with the following.
I have several Cisco's MDS9140 located in different rooms and locations (long distances). There are several dark fibre and DWDM links between the switches.
There are also several Clariion (CX models) connected to the first 8 ports of several switches.
Actually, I would need to connect a new CX4-480 to two of the switches in the same datacenter.
However, I have read that the MDS9140 has the first 8 ports for "target-optimized" connectivity, while the other ports are "host-orpimized" ports.
However, when looking the SAN from Cisco's GUI Fabric Manager/Device Manager, I can see that the ports 9-40 show up as "Host/Storage".
What happens is that the 8 first ports of the switches I want to connect the nex CX4 to, are already full, so I don't have anymore free ports from 1-8.
Can I connect the CX4 ports on other ports, on 9-40 ? Is there any minimum buffer credit requirement for storage ?
I think that the ports 9-40 have a default of 16 buffer credits per port.
Other Clariion's are already connected to some ports1-8, but I'm not sure this is mandatory.
I think ports 1-8 are mostly used for long distance ISL's (TE ports).
Thank you for your comments/advice.
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Lots of questions and I'm not sure about a few, but I know the first 8 ports are non blocked (non oversubscribed), so that means each port has dedicated bandwidth. Ports 9-40 share their bandwidth. I'd put storage arrays on the first 8 ports and hosts on the remaining 9-40 ports. As for buffer req's, each port can accomodate storage as well as hosts, as long as they're reasonably closeby (multi mode, within a few hundred meters).
Is the 9140 still supported ? It's a rather old switch, isn't it ? It's 9124, 9134 and 9148 (new new new) nowadays in the 91xx range (for 3 years or so already).
Thanks for the quick answer RRR.
I have looked deepr into the buffercredits on 9140 from Cisco's papers.
We can read : "Up to 255 buffer credits for target-optimized ports (ports1 to 😎 and 12 per host-optimized ports (ports 9-40).
So, it is not possible to 'transfer' buffer credits from th eight first ports to ports 9-40, which have a default of 12 BC's.
I think you're right, it is best to connect the storage on one of the 8 first ports and the same for long distance ISL's.
Your oversubscription adevice is right as well.
The 9140 is an old switch, out of sales from 2007 I think.
Probably if new switches need to be added, it would be the ones you mention. 9124 is also old...
Hi back RRR, thanks for your feedback. Sorry but the scope has changed after some internal meetings.
I have been rethinking the architecture and finally, it could be that I can recuperate two 9140 switches to move to another room. This will be done "temporary", because the goal to renew the whole SAN in a couple of years, and as I have about 17 MDS switches, I want to do all at the same time.
After a deep analysis of the used/free ports , it is possible (on paper...) to swap used ports from two switches to some others. I also have a 'spare' MDS 9140 available.
I have to take care, because I have several VSANs, but this is OK.
Now, two new questions arise :
I'm used with the Brocade's, where I can run a "clear" command.
Thanks for your inputs.
1) "write erase" will clear existing configuration, after running that command i typically run "reload" and begin configuring basic configuration
2) can you put those ports in "dedicated" mode ? Because they need to be in dedicated mode to be type "E or TE". If you can set them to dedicated mode i don't see why they can't be used for ISLs.
Thanks for the answers dynamox.
OK for 1.
For 2., I think this should be possible as you tell (dedicated mode). But I think that the ports 9-40 should not be used for long distance ISL's, am I wrong ?
Any extra advice is still welcome.
you probably right, we had to get at least a 9222i because it has more buffer credits for long distance connectivity.
Hi back all, to be sure I understand correctly...the initial question still applies.
dynamox suggests to connect the storage ports on the first 8 ports opf the MDS 9140.
But as the CX4 will be connected locally (I mean, in the same rack as the switches), is this mandatory ?
Of course, other hosts from other remote switches (long distance) would connect ot this storage, but then I will use ports 1-8 for the ISL's.
Regarding the "normal" ISL's, i.e., the ISLs from switch to switch in the same rack, can we use ports 9-40 without problem ?
Look at the diagram below : both switches are mounted in the same local rack :
Not sure the ISL need to be connected to ports 1-8 absoultely. Any idea ?
For long distance, we agree; ports 1-8 should be used.
Any extra advice is welcome.
I believe on the 9140 each set of 4 ports outside of 1-8 are considered a port group (you can see the grouping by right clicking on the switch and clicking over subscription). In these gen 1 switches they share 2.5 Gbps bandwidth. If you were to use one of these as an ISL, in dedicated mode, you would need to put the remaining 3 ports in out-service mode. If you used them for storage you would have the ability to leave them in shared mode. Just know that each connection in that port group will compete over that 2.5 Gbps.
I don't think the distance between the two devices really comes into play here. Think about how fast light really travels. Going 100 meters vs 1 meter isn't doesn't eally add time. Your delays will be within the switches and other devices.
How many storage and ISL ports are you looking to accommodate per switch?