01-31-2013 01:56 PM
First of all, I apoligize if this is not the correct forum to ask this question. I think it is the correct one, but I may be wrong.
I am no expert in fabrics switches, but I do want to learn more and this is why I am posting here.
We have 2 IBM BlaceCenter H with 1 Brocade Fabrics IO in each. The 2 BladeCenter are not in the same physical location. There is about 5KM between them. We use these BladeCenter for VMware mostly. Each BladeCenter is connected to an IBM DS3400 through the Brocade fabrics switches.
We would like to connect both Brocades through mono fiber. Once both Brocades are connected together, the VMware hosts from the Site A will be able to talk directly to the SAN in Site B and vice versa. We will then be able to do a Storage VMotion without powering off the VM.
While we are waiting for the Mono SFPs to arrive, I am doing some researches on how we will be able to connect my 2 Brocades together. I have come accross some tutorials talking about Full-Mesh and Core-Edge. See this tutorial here : How to merge two Brocade fabrics - NetworkAdminKB.com
From what I have read, I need to have a Fabrics license on both Brocades. I have confirmed that. I also read about the Extended Fabrics license, which I believe is required if the distance between both switches is greater than 10KM. Our fiber run is about 5KM so I don't think we will require an Extended Fabrics license.
I am not looking for all the steps by steps, but I would like to know if I need to merge my Brocades together or if I can just link both Brocades like Ethernet switches. Keep in mind that I want my devices from Site A to see all devices from Site B and vice versa. I am already aware of the Zoning concept and I have configured zoning properly in our Brocades. I understand that merging 2 Brocades together will also merge the zones, but I don't know if it is possible to achieve what I need without merging. If so, how would the Zoning work ?
There are 2 concerns about merging Brocades that are not in the same physical location. How would they react if the link (ISL) between them is lost ? Will they still work properly and reconnect when the fiber is back ? And the other concern is the downtime required to merge, but I guess I can schedule a downtime in few weeks.
I'm sorry if this topic is a little vague. What I'm looking for is to understand if merging my Brocades is required for what I need to achieve or if there are other options that are better suited for my needs.
Thanks for any help/input. I appreciate it
01-31-2013 02:28 PM
No, given your description, merging is your only option. Technically it would be able to connect them both to a multiprotocol router and route the device access from one fabric to the other while keeping them separated, but if you don't already have one, they are much more expensive to buy.
With the proper preparation you don't need much downtime. For example you could already prepare the zoning, or even let the BNA (enterprise trial) do it.
About loosing the link: Of course it depends on how you handle the fiber, but usually a healthy link (cable known good and clean, both SFPs known good and clean) will not loose the connection. If it happens once for a short period of time (max a few seconds) your hosts will notice recoverable errors (command timeouts) and will do the error recovery as soon as the link comes back and the fabric is rebuilt. If the ISL is toggling (on and off again and again) you'll surely get into trouble. But conditions like that are seldom and can be prevented or be coped with properly.
02-01-2013 05:57 AM
Thank you Sebastian for that very quick response. Now, I know that merging is my only viable option. We do not have a multiprotocol router.
About loosing the link, I was thinking about this yesterday night and that specific link between the Brocades will only be used during Storage VMotion. I am not planning on running a VM on a host at Site B while it is stored in the SAN of Site A. For optimal performances, I want my VM to run at the site where it is stored. Therefore, this 8GB Mono link will only be used when moving VMs from a SAN to another. So, I think loosing the link is not critical, mainly because the network (and heartbeats) goes through another fiber using Cisco switches.
How would the Brocades react when loosing the ISL ? I know my hosts will be fine the way I want to use it. Would they still be working but separately ? Because that 8GB Mono between the Brocades is not essential and business critical, if we loose it for few days (for whatever reasons), will the hosts at Site B still be able to talk to their SAN on site B and stuff at Site A to their SAN as well ?
Again, thank you