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The SRDF SRA does not utilize Solutions Enabler CLI commands to manage the VMAX/PowerMax storage arrays. The adapter utilizes API calls to perform any storage control operations. This feature optimizes the performance of the adapter for large, replicated environments. These are the types of environments frequently encountered when VMAX/PowerMax storage arrays are deployed in enterprise solutions.
The SRDF SRA for VMware SRM utilizes Solutions Enabler software to perform the discovery and management of the VMAX/PowerMax storage arrays on behalf of SRM. The Solutions Enabler software uses in-band commands to small devices called Gatekeepers to manipulate the VMAX/PowerMax storage arrays. Therefore, Solutions Enabler must be installed on a host that has access to Gatekeepers from the storage array that owns the replicated devices presented to the VMware environment. The simplest configuration on Windows would be running Solutions Enabler on the SRM server which has direct access to the storage. This is not possible with the SRM Appliance since Solutions Enabler is not supported within the Docker container.
The more common deployment of Solutions Enabler for the SRDF SRA, however, is a client-server model as that is what is required with the SRM Appliance. The communication between the Solutions Enabler commands executed by the SRDF SRA and Solutions Enabler API server occurs over a TCP/IP network. Solutions Enabler can be installed on any virtual or physical machine that is running a supported operating system. For further details on these methods refer to the Solutions Enabler Installation Guide. As mentioned previously, while it is possible to use the embedded Solutions Enabler on the array it is not recommended as it cannot be scaled.
Note: The term Solutions Enabler server is simply the name given to a Solutions Enabler installation that has its server daemon turned on and configured. A Solutions Enabler server is therefore a Solutions Enabler installation that can service remote API requests from remote clients. The installation distribution file for a Solutions Enabler server or client is the same.
Note: Dell has deprecated the Solutions Enabler Virtual Appliance in version 10.0.
Gatekeeper[11] devices are VMAX/PowerMax devices that act as the target of command requests from Solutions Enabler. These commands arrive in the form of disk I/O requests (and so a “disk” must be named by the host as the address or target of that command). The more commands that are issued from Solutions Enabler, and the more complex the actions required by those commands are, the more Gatekeepers and/or array processor resources that are required to handle those requests in a timely manner.
Gatekeepers require only a small amount of space, 3 cylinders (~3 MB). Users are discouraged from building Gatekeepers in larger sizes as the small size is used by Solutions Enabler to automatically identify and use devices as Gatekeepers. The direct presence of a Gatekeeper from an array to a Solutions Enabler install will cause the array of that Gatekeeper to be seen as a local array. Any arrays that do not have Gatekeepers present to that instance of Solutions Enabler but do have an RDF connection to or from an array that does, will appear in Solutions Enabler as remote arrays.
While in most cases Gatekeeper devices must be mapped and masked to single servers only and should not be shared across servers, virtualized environments offer an exception. VMware environments permit the movement of a virtual machine from one physical ESXi server to another (e.g., VMware vMotion, VMware HA). Therefore, if deploying Solutions Enabler on a VM, the Gatekeepers should be presented to all ESXi servers in the cluster so that the VM may move between the hosts in the event of failure or as a result of a DRS action. Note that while each ESXi server must be able to see the same Gatekeepers, the devices cannot be configured as shared (e.g., multi-writer or shared SCSI bus) as it is an unsupported configuration.
While the minimum requirement of six Gatekeepers per array is normally sufficient for most Solutions Enabler servers, as the SRM Solutions Enable servers manage Consistency Groups, additional devices are required. To calculate the required Gatekeeper count the following formula is provided:
[Number of CGs] * 0.3 = Gatekeepers needed for Consistency Group operation
Round the result of calculations up to whole integers and then do the following addition:
For example, an SRM environment that uses 3 CGs represented by 3 protection groups, would require 7 GKs (6 + 0.3*3 = 6.9 rounded to 7).
This holds true for all VMAX/PowerMax arrays.
[11] For more detailed information on Gatekeepers refer to Dell knowledge base article emc255976 on support.dell.com