disk access

this is for old fashioned mechanical harddisks obviously, they will be around for quite some time

when reading a fragmented disk you should first get all the positions of the data, and then sort by cylinder number, then start reading from the outside inwards w/o searching, just track-to-track operations since those are done within a milisecond

the disks should not be idle Рthey have to be either read, fill a cache, write, search sector/cylinder, defrag, encrypt, compress etc

it’s OK to read/write out-of-band sectors when it’s faster to do so

why can’t a disk controller compress data? or defrag data? or de-dupe data?
it’s slower than the host, but¬†they got all day, and unless it’s a busy server they are idle most of the time, and have now 64+ Mbyte cache, and must handle 1 Gbit/s and more throughput, so there seems to be some processing capacity