Connectivity using single mode fiber

Can you describe your topology?
Where do you have the FC Switches?
Normally you would interconnect to switches with singlemode Gbics (each of them in one building) together. Then you would connect the hosts to the local switches...

best regards
Manfred

The switches (9513s) are in the same room as the storage arrays and most of the hosts. There are a few hosts in another building which is connected to the main server room where the storage and switches are via single mode fiber. It is an option to interconnect some switches in the 'other' building but I also wanted to see if i could connect the hosts directly via single mode. thanks for your interest

Normally you'd attach hosts to the switches, so no special HBAs are needed. The interconnect between the switches should then be made over 9/125 SM, so the switches make sure you cross the extra mileage. the host doesn't see any of this.

If you don't want to buy extra switches (this could be simple 9124's or 9134's or so, direct atach seems like an option. But I must say: I've never seen HBA's with SM SFP's in them..... Try looking at the Qlogic site is my advice.

Single mode fiber is not an option for connecting to a Clariion array from a host. It is not designed for that type of connection. Single mode is design for the long haul connection and multimode is designed for the type of traffic that a host requires.

That being said you can use multimode fiber lengths of up to 100m. How far away is the building and is running mm fiber an option?

One option is to use a media converter from multimode to single mode at each site.
If the distance is less than 500 Meters you should be ok.
If the distance is longer, you may run into buffers limits. Fibre channel uses buffer credits to control packets flow.
this links explains buffer credits
http://searchstorage.techtarget.com/tip/0,289483,sid5_gci884636,00.html

Which is the main reason HBA 's don't come with sinlge mode.

And you won't be guaranteed that the solution will work consistently for you. Also it will be an unsupported solution as well. The long distance single mode connections are not host to array but switch to switch for replication of data not host level access.

Good article from Search Storage though, nice little FC nugget.

Just to clarify your statement Aran, when you say it "isn't designed for it" we may better say:

You can't connect single mode to a CLARiiON because the HBA ports (SP ports) use multi-mode shortwave SFPs. The single mode cable requires single mode long wave SFPs. The technologies are not compatible without some kind of bridge.

Yes that is a more accurate way to put it Allen, I over simplified my statement.

Multi-mode is the short-haul within-the-building fiber and is the connection type used for LAN/SAN switching and host connections, hence the equipment found in a LAN or SAN infrastructure is not designed for use with single-mode fiber.

Single-mode, while capable of higher bandwidth over long distances because of it's lack of dispersion and greater ability to retain the fidelity of each light pulse, is also much more expensive and difficult to implement. I doubt the post will find a solution that enables host-to-array connectivity using single-mode fiber.