Synchronization of a dispersed RAID group

摘要

In a memory system where memory units may be separated from each other so as to operate substantially independently, the coordination of related memory operations between such units may be by synchronization of an epoch of time and the start of an epoch of time with a common synchronization source. The source may be distributed directly to each of the memory modules of a memory unit, or through an intermediate synchronization circuit of a memory unit that is common to the modules. Where the data is stored as a RAID stripe on a plurality of synchronized modules, the read and write or erase operations performed by the modules may be arranged such that the write operations or erase operations may not substantially affect the ability to promptly read the stored data of a RAID stripe.

主权项

1. A method of operating a data storage system, the data storage system comprising a plurality of memory units configured to store and retrieve data, each memory unit comprising a plurality of memory modules, the method comprising:
selecting a RAID group comprising at least one memory module of each of a group of memory units of the plurality of memory units; configuring the memory modules of the RAID group to have a frame time having an integral number of epoch times; maintaining a synchronization of a start time of the frame time by receiving, at each memory unit, a same periodic signal having a period that is an integral multiple of the epoch time; adjusting a time-determining circuit at each of the memory modules so as to minimize a difference between the start time of the frame time at each memory module and the same periodic signal; and operating the memory modules of the RAID group such that data previously written to the memory modules of the RAID group is retrieved without delay due to at least one of writing data to or performing an erase operation on the RAID group.