Provided are techniques for transmitting blocks of data. It is determined
whether any high priority out of sync (HPOOS) indicator is set to
indicate that a number of modified segments associated with a block of
data are less than or equal to a modified segments threshold. In response
to determining that at least one high priority out of sync indicator is
set, one or more sub-blocks of data in the modified segments associated
with the block of data and with one set high priority out of sync
indicator are transferred.