The extra parameter tells hdparm to write the settings to disk so that they
will be used each time you boot, ensuring optimal disk performance in the
future.
The man page entry for hdparm is extensive and contains useful detailed
information, but because the kernel configuration selected by Ubuntu already
attempts to optimize the drives, it might be that little can be gained through
tweaking. Because not all hardware combinations can be anticipated by
Ubuntu or by Linux, and performance gains are always useful, you’re
encouraged to try.
TIP
You can use the hdparm command to produce a disk transfer speed result
as follows:Click here to view code image
matthew@seymour:~$ hdparm -tT device
Be aware, however, that although the resulting numbers appear quantitative,
they are subject to several technical qualifications beyond the scope of what
is discussed and explained in this chapter. Simply put, do not accept values
generated by hdparm as absolute numbers but only as a relative measure
of performance.File System Tuning
Never content to leave things alone, Linux provides several tools to adjust and
customize file system settings. The belief is that hardware manufacturers and
distribution creators tend to select conservative settings that will work well all
the time, leaving some of the potential of your system leashed—which is why
you have chosen Ubuntu Unleashed to help you.
The Linux file system designers have done an excellent job of selecting
default values used for file system creation, and any version of the Linux
kernel after 2.6.x contains code for the IDE subsystem that significantly
improves I/O (input/output) transfer speeds over older versions, obviating
much of the need for special tweaking of the file system and drive parameters
if you use IDE disks. Although these values work well for most users, some
server applications of Linux benefit from file system tuning. As always,
observe and benchmark your changes.
SYNCHRONIZING THE FILE SYSTEM WITH sync
Because Linux uses buffers when writing to devices, a write will not occur