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This chapter describes the requirements and guidelines that are necessary to successfully deploy your Cisco I/O Accelerator SAN. Read this chapter before installing or configuring Cisco I/O Accelerator (IOA).
This chapter includes the following sections:
This section includes the following topics:
Figure 1 illustrates the core-edge topology where you are recommended to place the IOA interfaces (MSM-18/4 or SSN-16) in the core switches that interconnect the two sites. The ISLs interconnecting the two sites over a MAN or WAN are typically on the core switches as well, so this becomes a natural place to deploy the IOA service. This deployment provides the following benefits:
Provides consolidation of IOA service at the core.
Allows easy scalability of the IOA service engines based on the desired throughput.
Allows you to plan and transition from FC or FCIP acceleration solutions to IOA. This is because these acceleration solutions will likely be deployed at the core switches already and will allow for a smooth transition to IOA.
Facilitates planning the capacity based on WAN ISL throughput on the core switches themselves.
Provides optimal routing as the flows have to traverse these core switches to reach the remote sites.
Figure 1 illustrates the edge-core-edge topology where you are recommended to place the MSM-18/4 Module or SSN-16 Module at the core switches that interconnect the two sites.
Figure 1 illustrates the collapsed core toplogy where you are recommended to place the MSM-18/4 Module or SSN-16 Module (IOA interfaces) in the core switches that interconnect the two sites.
Figure 1 illustrates the extended core-edge topology where you are recommended to place the IOA interfaces (MSM-18/4 Module or SSN-16 Module) in all the core switches. As the IOA service load balances the traffic by selecting any IOA interface from each site and forms the IOA interface pair for a given flow, certain failures may result in suboptimal routing. The recommendation is to interconnect the core switches within each site for maximum availability of the IOA service. The ISLs between the core switches in the specific site has as much throughput as the WAN ISLs between the sites.
Figure 1 illustrates the IOA implementation where the IOA service is extended across multiple sites. In this example, Site-4 consolidates the tape backup from Site-1, Site-2, and Site-3. Each IOA cluster represents a site pair, which means that there are three unique clusters. This topology provides segregation and scalability of the IOA service across multiple sites. In Site-4, a single switch participates in multiple IOA clusters.
Note | Starting from Cisco MDS NX-OS Release 6.2(1), IOA with IVR is not supported. |
For IOA to support IVR flows, we recommend that you place the IOA interfaces on the MSM-18/4 or SSN-16 module in the IVR border switches for optimum routing. IOA must always be deployed on the host and target VSANs. Packets from the host get redirected to the IOA interface in the host VSAN, traverses the IVR transit VSANs for routing, and again gets redirected to the IOA interface in the target VSAN before it reaches the target and vice-versa. IVR transit VSANs are used only for FC routing. IOA is not supported or deployed on transit VSANs.
For more information, refer to the Cisco MDS 9000 Family NX-OS Inter-VSAN Routing Configuration Guide.
In certain other topologies, the edge switches are connected across the WAN. With these topologies, we recommend that you do the following:
Note | IOA is supported for IVR flows starting from Cisco MDS NX-OS Release 5.0(1a). |
Deployment Guidelines
When you deploy IOA, consider these general configuration guidelines:
For maximum scalability and optimal performance, follow these IOA configuration guidelines:
When you configure IOA, consider the following Zoning requirements:
When you configure IOA, consider the following resiliency guidelines:
Caution | Modifying the default setting to a lower value results in quick link failure detections. You must make sure that this is appropriate for your deployment. We recommend that you modify the default setting only for those applications which are sensitive to E_D_TOV values. For other applications, the default configuration is sufficient. |
When you configure IOA, consider the following guidelines and limitations:
Note |
%ACLTCAM-2-ACL_TCAM_NO_TCAM_LEFT: ACLTCAM resource exhausted for interface on fcx/y.
The above message indicates that the ACLTCAM usage for Region2 Security on the Cisco MDS 9250i Switch or the Cisco MDS 9148S Switch is full. Due to this, a few IOA flows may be offline. This is the expected behavior. In such a case, ensure that the number of flows that get bound to the IOA node on the Cisco MDS 9250i Switch is not more than 203.
If either the hosts or the targets that are participating in IOA are connected to Cisco MDS 9148S Switch, then the maximum number of hosts or targets you can have is 203.
Note | To view the ACLTCAM usage on the Cisco MDS 9250i Switch or the Cisco MDS 9148S Switch, use the show system internal acltcam-soc tcam-usage command. |
If FCIP is configured on a Cisco MDS 9700 Series switch and IOA VSAN is a part of that FCIP tunnel, then the targets participating in IOA cannot be locally present on that switch.
Cisco I/O Accelerator Configuration Limits lists the IOA configurations and the corresponding limits.
Parameter |
MSM-18/4 or SSN-16 Module on MDS 9222i and MDS 9500 modular Chassis and MDS 9250i Fabric Switch |
---|---|
Number of switches in a cluster |
4 |
Number of clusters per switch |
16 |
Number of switches in a SAN fabric for FC-Redirect |
34 |
Number of hosts per target |
128 |
Number of concurrent flows per IOA service engine |
128 |
Number of flows per IOA service engine (hard limit) |
128 - Release 4.2(1) on MDS 9222i/MDS 9500 512 - Release 4.2(7) or later on MDS 9222i/MDS 9500 512 - Release 6.2(5) or later on MDS 9250i |
Number of flows per IOA service engine (soft limit) |
64 - Release 4.2(1) on MDS 9222i/MDS 9500 256 1 - Release 4.2(7) or later on MDS 9222i/MDS 9500 256 1 - Release 6.2(5) or later on MDS 9250i |
Number of flows in a cluster |
1024 - Release 4.2(7d) 1248 - Release 5.2(6b) |
Note | When the new flows are load balanced again to the functional IOA interface, the soft limit is enforced to account for IOA interface failures. If the number of switches in the SAN exceeds the scalability limit, consider using CFS regions as described in Using FC-Redirect with CFS Regions. |