Priority scheme for transmitting blocks of data

A method for transmitting blocks of data, comprising:

• maintaining high priority out of sync indicators in a high priority out of sync structure, wherein each high priority out of sync indicator is associated with a block of data, wherein a high priority out of sync indicator is set in response to determining that a number of modified segments associated with a block of data is equal to or less than a modified segments threshold, wherein the high priority out of sync indicator is reset in response to determining that the number of modified segments associated with the block of data is greater than the modified segments threshold, wherein the modified segments threshold represents a number of segments that have been modified, and wherein a modified segment is a segment in primary cache that includes at least one modified sub-block of data for a block of data;
• determining whether any high priority out of sync indicator is set in the high priority out of sync structure to indicate that a number of modified segments associated with a block of data are less than or equal to the modified segments threshold;
• and
• in response to determining that at least one high priority out of sync indicator is set, transferring one or more sub-blocks of data in the modified segments associated with the block of data and with the at least one set high priority out of sync indicator.