Monday, August 04, 2008

Brocade LSAN - Concepts

LSAN is the sharing of resources across fabrics. You need a MPR or a FR4-18i blade in the 48K to be able to connect the 2 fabrics - yet keep them unmerged. Just to make it more clear, the other option to scale out, is to connect the 2 switches in either fabrics. If you do this, you are actually merging the 2 fabrics. MPR's restrict the type of RSCN's propgated, with the help of special port EX. You have to designate a port on the MPR as EX, and once u do this, although data frames can pass via the MPR, the RSCN's responsible for fabric merge are suppressed.

To share a target (ex: tape drive) in Fabric 1 in DC1 to a server (initiator) in Fabric 2 in DC2, you need to create a LSAN in both fabrics. Remember

1. LSAN's ideally should be named the same (not compulsary). Naming convention shd follow LSAN_FabricName_InitiatorName_FabricName_TargetName

In my case I will name it as

2. An LSAN should have atleast one initiator and one target. Ideally have only one initiator and one target and not more, but there is no restriction.

3. And LSAN should have the same members. If u have a 3 DC solution like I have, you will have to create seperate LSAN's to share the same resource to 2 fabrics. For ex if u want to share the tape drive to hosts in DC2-F2 and DC3-F1



I will continue with a post on howto create LSAN's and also how to troubleshoot issues in a routed fabric. If you have queries please post in the comments section. Queries on comparison with CISCO VSAN are also welcome.

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At 7:22 AM, Blogger hereiam abhi said...

good post biju... I suggest its a good blog for beginners, want to learn on SAN, UNIX.


At 2:08 AM, Blogger Samuel Sivaneswaran said...

Good article.. I'm also based in CBJ, currently working on a LSAN project. Drop me an email at Maybe we could share knowledge and catch up.

At 2:25 AM, Blogger Sunil said...

Thanks for the article..could youexplain how LSAn suppress flow of RSCN from one fabric to another?


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