Using the decommission command for buffer allocation is only supported on the 7210 SAS-Dxp (all variants). For each port receiving reallocated resources from port decommissioning, a maximum of two ports can be decommissioned.
This feature enables the user to make efficient use of the available port egress queue buffer pool by allocating queue buffers of the unused ports to other ports. Services cannot be configured on the unused ports as software takes away all the queue buffer resources from these ports and allocates it to ports that need increased amount of buffers to handle larger bursts. This allows the operators who use limited number of ports to deploy services, to increase the amount of queue buffers allocated to them by decommissioning ports that are not used to deploy services.
The amount of credit of queue buffers received by a port is used to increase the MBS portion of the buffer pool of the port. This allows any queue on the port to use the buffers, if needed. The CBS portion of the queue is not modified with this feature.
The system has to be rebooted after decommissioning of ports for the queue buffers to be reallocated and the configuration to take effect.
The users have an option to specify the groups of ports which receive the credit of queue buffers freed up using the decommission command. With this option, the user can specify a port or group of ports which receives the credit of queue buffers. For example, it is possible for the user to configure decommissioning of four fixed copper ports and allocate the freed queue buffers to the remaining copper ports in the system or decommission four fiber ports and allocate the freed up queue buffers to the 10G ports, and so on. This mechanism allows the operators to provide higher amount of queue buffers to a specific port or a group of ports, allowing them to pick and choose ports that need the extra buffers for burst absorption.
The user is allowed to increase the per port MBS pool limit so that more buffers are available to absorb larger bursts, at the cost of decommissioning ports which are not used to configure services.