Re: Is Parallel Programming Hard, And, If So, What Can You Do About It?

No, when the disk receives a write command, it accepts the write data
immediately (up to some large limit).  That way, when the heads settle on
the track, if the disk happens to be positioned in the middle of the
transfer, it can write the last part of the data to the disk immediately,
then wait for the disk to spin to where the transfer starts to finish the
transferring the first part of the write data.  This reduces average
latency, i.e. improves performance.

Really?  I had the impression that it would be very hard to start writing
from the middle of a sector because of the need to be sure exactly where
in the sector we are.  IOW, the drive needs to see the inter-sector markers
before it can start writing to a sector.


        Stefan