Dual Loop on FC DAS 1

[estech25]

I successfully installed the Fibre Channel DAS thanks to all the help from you guys. There are some very important questions I need to ask you though
1. My Storage is a dual loop one. It could be connected to two hosts and has two ports for each. I have one LUN on the storage. Can I connect the storage to one host using two optic cables and be able to get 800MB/s instead of the Fibre Channel 400MB/s from it simply because it is dual loop? What is this dual loop feature basically good for? Can it increase bandwidth when I have just one LUN? Can one LUN be on two loops?

2. My storage has two modes of connection for each port :AL and Fabric. I have an HBA and it wouldn't recognize the storage unless I set the connection mode on the storage to Fabric. Why is this? When should I use AL?

 

[Chacalinc]

Can I connect the storage to one host using two optic cables and be able to get 800MB/s instead of the Fibre Channel 400MB/s from it simply because it is dual loop?

Yes and no, actually it depends. You can connect 2 FC Channels in order to see the same LUN, but you need a piece of software to support it. With no software, you going to see the same LUN twice and the OS will not be able to use as you want (except for some drivers as Emulex or QLogic). In order to get more bandwith isung the 2 channel you need a software that can do that. I.e. EMC, with clariion and symmetrix, has a software called PowerPath, it has the feature to give you automatic high availability and load balancing. HP qith the EVA has some other software as Hitachi, NEC has Path Manager, etc. etc.

I'm pretty sure that if you have some basic disk array you can not have this feature. (just a though).

What is this dual loop feature basically good for?

high availability and load balancing (if you have the correct software)

Can it increase bandwidth when I have just one LUN?

yes, with software.

Can one LUN be on two loops?

Yes, as stated above.

I have an HBA and it wouldn't recognize the storage unless I set the connection mode on the storage to Fabric. Why is this? When should I use AL?

that's weird. In a direct attach environment, the protocol must be FC-AL, fabric is used when you are using FC switches.

May be, my though is, you have a disk array who has an internal FC switch.

Hope this helps.

Cheers.