About Cisco I/O Accelerator
The Cisco MDS 9000 Family I/O Accelerator (IOA) feature provides Small Computer System Interface (SCSI) acceleration in a storage area network (SAN) where the sites are interconnected over long distances using Fibre Channel or Fibre Channel over IP (FCIP) Inter-Switch Links (ISLs).
IOA provides these features, which are described in the following sections:
Unified Acceleration Service
IOA provides both SCSI write acceleration and tape acceleration features as a unified fabric service. These services were provided in previous releases in the form of Fibre Channel write acceleration for remote replication over Fibre Channel links and FCIP write acceleration and tape acceleration over FCIP links. Fibre Channel write acceleration was offered on the Storage Services Module (SSM) and FCIP write acceleration and tape acceleration were offered on the IP storage services modules. IOA offers both the write acceleration and tape acceleration services on the Cisco MDS MSM-18/4 module, SSN-16 module, and 9222i switch as a fabric service. This eliminates the need to buy separate hardware to obtain Fibre Channel write acceleration and FCIP write acceleration and tape acceleration.
IOA can be deployed anywhere in the fabric without rewiring the hardware or reconfiguring the fabric. There are no restrictions on where the hosts and targets are connected to. Both the Fibre Channel and FCIP write acceleration is supported only on PortChannels but do not support multiple equal-cost links. FCIP tape acceleration is not supported on PortChannels. IOA eliminates these topological restrictions.
IOA is completely transport-agnostic and is supported on both Fibre Channel and FCIP ISLs between two sites.
High Availability and Resiliency
IOA equally supports both PortChannels and equal-cost multiple path (ECMP) links across two data centers. This allows you to seamlessly add ISLs across the two data centers for capacity building or redundancy. IOA is completely resilient against ISL failures. IOA uses a Lightweight Reliable Transport Protocol (LRTP) to guard against any ISL failures as long as there is an alternate path available across the two data centers. Remote replication and tape backup applications are completely unaffected by these failures.
Improved Tape Acceleration Performance
IOA tape acceleration provides higher throughput numbers than the FCIP tape acceleration, which is limited by a single Gigabit Ethernet throughput.
IOA uses clustering technology to provide automatic load balancing and redundancy for traffic flows across multiple IOA service engines that can be configured for the IOA service. When an IOA service engine fails, the affected traffic flows are automatically redirected to the available IOA service engines to resume acceleration.