We are constantly asked about the differences between Fibre Channel and SAS connectivity layers for LTO tape. Here's a bit of info that may help you better understand when to use either of these protocols.
Performance between SAS and Fibre Channel drives is identical. Aside from pricing differences (FC models average around $900 more than the same SAS model), there are other important infrastructure issues that must be considered.
Why should I choose a SAS solution?
If you are working in a standalone or ethernet connected environment, a SAS bundle provides an easy to set up solution because once you have your SAS HBA installed in your workstation, SAS connectivity operates much like USB since most operating systems will support disconnecting and reconnecting a SAS tape solution in much the same manner as a USB mouse or keyboard. This makes a SAS bundle a plug and play solution for most situations. The only limitation to SAS connectivity is that you must have a host system that can support the addition of a PCIe HBA in an x4 or x8 (preferred) slot, or in a Thunderbolt-connected PCIe chassis.
Why should I choose a Fibre Channel (FC) solution?
If you are working in an environment where you already have an existing FC Fabric in place, choosing the FC option for our bundles is often the best solution. You can attach the FC library to your existing switched fabric, zone the library and a specified workstation for use in backup and archival operations and you’re ready to go. As mentioned there, the only thing that you must take into account is that a tape library does not work well with many possible controlling workstations in an open-zoned fabric. You must create a zone for the library and assign one specific workstation to that same zone. This workstation then becomes the system used to perform backup and archival operations.
On the other hand, if you don’t have an existing FC infrastructure, or you prefer a simpler connection with your workstations that is separate from your FC fabric, starting out with a FC-connected tape storage bundle is not a path that we recommend due to both the complexity and additional costs involved.
What about other connection types — Thunderbolt, iSCSI, USB, and Firewire ?
Thunderbolt solutions are available by using Thunderbolt to PCIe adapters like those from Sonnet Technology. This allows you to connect a SAS tape device to your Thunderbolt-enabled system through the use of a normal ATTO Technologies ExpressSAS HBA.
For the other types, aside from slower, much lower capacity devices such as DAT and dead-end technologies like DLT, AIT, and VXA, there are no tape solutions available for these alternate technologies.
For most users, SAS provides the best and easiest to use solution. However, if you currently have an existing FC fabric and the knowledge inherent with managing such an infrastructure, an FC unit can be a great solution.