On 07 Dec 1998 12:23:19 -0500, Stefan Monnier
<monnier+lists/linux/kernel/news/@tequila.cs.yale.edu> said:
> I noticed that my backups always report a discrepancy in the dump-speed
> of my / and /home partitions:
> The / and /home partitions are on the same SCSI disk, using the ncr53c8xx
> driver.
If you have two different partitions on the same disk, then they will
almost certainly have different bandwidths. Disk tracks on the outside
of a platter are longer than those near the middle, and can therefore
carry more data. However, the disk spins at a constant angular
velicity, so an entire track of data is always transferred in the same
amount of time. As a result, the tracks with more data on transfer that
data more rapidly than the less populated tracks near the center of the
disk.
Pretty much all modern disks display this disparity in bandwidth. The
difference is very significant: it can be as much as a 2:1 improvement
in raw bandwidth over the surface of a platter.
--Stephen
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