The threshold amount of buffer space that can be allocated within the operating system to handle incoming writes is defined by the tunable vol_min_lowmem_sz. You can raise the threshold by increasing the value of the tunable vol_min_lowmem_sz. It should be set to, at least, 3 x N x I, but not less than 520K, where N is the number of concurrent writes to replicated volumes, and I is the average I/O size, rounded up to 8 kilobytes. The vol_min_lowmem_sz tunable is auto-tunable and depending on the incoming writes, VVR will increase or decrease the tunable value. The value that you specify for the tunable, using the vxtune utility or the system-specific interface, will be used as an initial value and could change depending on the application write behavior. Note that this tunable is used only when replicating in asynchronous mode because SRL is not read back when replicating in synchronous mode. For more information on using this tunable, refer to VVR Planning and Tuning Guide