	US 12,111,841 B2
	Automatic consistency group scale-out for any point in time replication systems
Jehuda Shemer, Kfar Saba (IL); Erez Sharvit, Ramat Gan (IL); and Valerie Lotosh, Ramat Gan (IL)
Assigned to EMC IP Holding Company LLC, Hopkinton, MA (US)
Filed by EMC IP Holding Company LLC, Hopkinton, MA (US)
Filed on Apr. 20, 2021, as Appl. No. 17/235,391.
Prior Publication US 2022/0335059 A1, Oct. 20, 2022
Int. Cl. G06F 16/27 (2019.01)

CPC G06F 16/27 (2019.01) [G06F 16/273 (2019.01); G06F 16/275 (2019.01); G06F 16/278 (2019.01)]

14 Claims

1. A method, comprising: measuring a journal distribution lag of a journal, wherein the journal distribution lag is a measure to determine an amount of data that has reached a replication appliance but has not yet been distributed by the replication appliance to the journal;

evaluating a first operational measure at a production appliance, and evaluating a second operational measure at the replication appliance, which is operable to communicate with the production appliance;

determining a scale out for a consistency group of the replication appliance is needed based on the journal distribution lag exceeding a threshold, the first operational measure, and the second operational measure, wherein the threshold defines an amount of memory available to the replication appliance of the consistency group;

implementing the scale out of the consistency group;

wherein when the scale out is implemented at a time ‘T,’ a barrier point is defined and inserted in the journal at the time ‘T,’ and the replication appliance of the consistency group is required to stop writing to the journal when the barrier point is reached;

and wherein after all replication appliances in the consistency group have reached the barrier point in their respective journals, and partitions of an address space corresponding to the consistency group have been updated, the replication appliances are permitted to begin, or resume, writing to their respective journals.