Patent ID: 7523275
Filing Date: 2009-04-21
Classification: G06F

Abstract:
1. A method for maintaining a copy relationship between at least one primary volume and at least one corresponding secondary volume, wherein data in the at least one primary volume in the copy relationship is copied to the corresponding at least one secondary volume in the copy relationship, comprising: generating writes comprising data in the at least one primary volume to copy to the corresponding at least one secondary volume in the copy relationship in a first write mode; generating writes comprising write requests to the at least one primary volume in the copy relationship to copy to at least one corresponding secondary volume in a second write mode; transferring a plurality of the writes to the at least one secondary volume in the second write mode before processing at least one write to the secondary volume in the first mode; and delaying processing writes to the at least one secondary volume in the first write mode for a set time period after processing writes to the at least one secondary volume in the second write mode; receiving a subsequent write to one primary volume in the copy relationship in the second write mode during the set time period; and processing the subsequent write in the second write mode received during the set time period over pending writes to the at least one secondary volume in the first mode.