By Dave Simpson
Cisco recently announced hardware and software that will make it easier for application vendors to port to the company's MDS 9000 switches to create what Cisco refers to as "intelligent fabric applications" (e.g., network-based volume management, remote replication, backup/recovery, continuous data protection, etc.).
The applications are enabled, in part, by Cisco's use of the yet-to-be-ratified Fabric Application Interface Standard (FAIS), which other switch vendors and application developers will support. FAIS provides a common framework for implementing storage applications in SAN-based devices.
The combination of Cisco's new Storage Services Module card, a follow-on to the Advanced Services Module (ASM), and the 2.1 release of its SAN-OS software enables third-party developers to write to a common platform, as opposed to writing to different platforms, which was the case in the past. The SSM is an ASIC-based 32-port Fibre Channel line card that plugs into MDS switches/directors.
Cisco divides intelligent fabric applications into three categories: network-hosted, network-assisted, and network-accelerated storage applications.
Network-hosted storage applications (i.e., volume management) run entirely in MDS switches on the SSM card. In this implementation, the switch controls the data path and data manipulation, according to Paul Dul, senior product line manager in Cisco's storage technology business unit.
EMC, IBM, and Veritas are expected to be among the first vendors to deliver network-hosted applications for Cisco's switches. Veritas Storage Foundation for Networks (VSFN) virtualization software, which already runs on Cisco's ASM cards, is expected to be available for the SSM cards in the June time frame. IBM plans to port its SAN Volume Controller (SVC) to the SSM cards. EMC's "Storage Router" virtualization software is not expected to ship until the third quarter, although Cisco and EMC demonstrated a prototype implementation earlier this month at the CeBIT conference.
Running storage virtualization on switches is an alternative to running it on disk arrays, an approach favored by Hitachi Data Systems with its TagmaStore arrays, or on host servers.
In contrast to network-hosted applications, which run on the switch, network-assisted applications typically run on stand-alone appliances that are connected to the switch via Fibre Channel. In this type of implementation, third-party applications communicate with SSM cards via Cisco's SANTap Service protocol, which has been included in SAN-OS 2.1.
According to Cisco's Dul, the network-assisted approach makes the storage applications more "robust" compared to running them on a stand-alone appliance. He says that coupling appliance-based applications with the MDS SSM cards increases reliability and performance. In addition, this approach does not require host agents that are typically required with the stand-alone appliance approach, according to Dul.
Cisco announced that the following companies will be among the first to deliver network-assisted applications that support the SANTap Service protocol: Alacritus Software, Cloverleaf Communications, FalconStor Software, Kashya, Topio, and XIOtech. Delivery times for these applications--which include replication, snapshots, point-in-time copy, continuous data protection, etc.--vary by vendor.
Currently designed to address backup performance and SAN extension issues, network-accelerated storage applications are enabled by Cisco. For example, the company provides Network-Accelerated Serverless Backup, which uses the standard Extended Copy technique to offload data movement from backup servers to the SSM switch cards (each of which has up to 16Gbps of throughput). In other words, this service eliminates the "heavy lifting" normally done by backup servers and, via hardware accelerators, speeds up backup times. Although the media server still maintains control functions, it is taken out of the data path.
In internal testing, Network-Accelerated Serverless Backup provided a 30% improvement in backup speed, according to Dul.
Computer Associates (BrightStor software), CommVault Systems (Galaxy), and Veritas (NetBackup) were among the first vendors to announce that their backup applications will support Network Accelerated Serverless Backup on MDS switches.
To improve SAN extension applications, Cisco introduced Fibre Channel Write Acceleration, which is similar to Cisco's FCIP Write Acceleration except that it runs over native Fibre Channel. This capability provides improved performance for third-party replication applications (although no applications have been qualified yet). In its lab tests, Cisco reported a 30% increase in replication performance over a 125km DWDM link, says Dul.
As the fabric-based application market develops, Cisco is expected to compete primarily with Brocade and McData. However, a number of smaller start-ups, including Cloverleaf, Maranti Networks, MaXXan Systems, and Troika Networks, are already in the market with switches or dedicated appliances that host network-based storage applications.