Abstract: An aspect of performing on-demand remote snapshot creation for a synchronous replication session between a local system and a remote system of a storage system includes receiving a request for the remote snapshot on the remote system and identifying a current state of the synchronous replication session. The current state is one of a plurality of states. An aspect also includes implementing one or more actions with respect to the remote snapshot as a function of the current state. The actions are performed prior to transitioning from the current state to another state of the plurality of states.

Abstract: An aspect of performing on-demand remote snapshot creation for a synchronous replication session between a local system and a remote system of a storage system includes receiving a request for the remote snapshot on the remote system and identifying a current state of the synchronous replication session. The current state is one of a plurality of states. An aspect also includes implementing one or more actions with respect to the remote snapshot as a function of the current state. The actions are performed prior to transitioning from the current state to another state of the plurality of states.

Abstract: A first storage system in one illustrative embodiment is configured to participate in a replication process with a second storage system. Each of a plurality of storage nodes of the first storage system comprises a plurality of storage devices and a set of processing modules configured to communicate with corresponding sets of processing modules on other ones of the storage nodes. In conjunction with the replication process, a first one of the processing modules is configured to generate a request message for transmission to a second one of the processing modules requesting that the second processing module transfer designated replication data to the second storage system. The request message comprises a unique message identifier that the second processing module incorporates into a subsequent response message transmitted back to the first processing module to indicate a result of the requested transfer of the designated replication data to the second storage system.

Abstract: An aspect of implementing bandwidth limits on replication sessions for a destination includes creating a list of routing modules having ownership of links going to the destination, calculating, by control modules, a proportionate share of a requested total bandwidth limit based on a number of slices owned and the number of routing modules. The proportionate share of the bandwidth limit is indicated by a budget value of a budget byte window (BBW). An aspect further includes prior to initiating a scan of the slices, identifying a BBW having a budget value equal or greater than the value, allocating the budget value to a thread, and reducing the budget value of the BBW by the predetermined value. An aspect also includes scanning the slices corresponding to the identified BBW, sending a number of bytes transmitted and corresponding number of pages to respective control modules resulting from the scanning, and updating corresponding BBW.

Abstract: An aspect of implementing bandwidth limits on replication sessions for a destination includes creating a list of routing modules having ownership of links going to the destination, calculating, by control modules, a proportionate share of a requested total bandwidth limit based on a number of slices owned and the number of routing modules. The proportionate share of the bandwidth limit is indicated by a budget value of a budget byte window (BBW). An aspect further includes prior to initiating a scan of the slices, identifying a BBW having a budget value equal or greater than the value, allocating the budget value to a thread, and reducing the budget value of the BBW by the predetermined value. An aspect also includes scanning the slices corresponding to the identified BBW, sending a number of bytes transmitted and corresponding number of pages to respective control modules resulting from the scanning, and updating corresponding BBW.

Abstract: An aspect of implementing bandwidth control for an asynchronous replication session includes calculating, by each of a group of control modules, a proportionate share of a requested total bandwidth limit based on a number of slices owned. The proportionate share of the bandwidth limit is indicated by a budget value via a budget byte window (BBW). An aspect further includes prior to initiating a scan of the slices by an initiator thread, identifying BBWs having a budget value equal to or exceeding a predetermined value, allocating the budget value for the BBWs to the thread, and reducing the budget value corresponding to the BBWs by the predetermined value. An aspect also includes initiating the initiator thread for slices corresponding to the identified BBWs, sending a number of bytes transmitted and corresponding number of pages to respective control modules resulting from the scanning, and updating corresponding BBWs.