Should root partition be first partition?

b. f. bf1783 at
Mon Feb 8 19:37:34 UTC 2010

> You can even
>leave gaps between partitions if you want, but that is pretty crazy
>since it just wastes some of the available space.
>There have been quite a lot of recommendations on how to lay out a disk
>for best performance, based on the observation that disk access times
>vary depending on how far away the data is from the spindle, and the
>expected usage patterns for the partition.  Like any such advice, it
>has tended to become less valid over time.  Modern disks really don't
>have any physical meaning to the Cylinder/Head/Sector style addressing
>schemes[*] nowadays -- and you're pretty much bound to be using LBA
>style addressing anyhow.  Also, machines nowadays have so much RAM that
>(a) swap is hardly ever used and (b) access to popular files is
>frequently answered out of VM caches rathe than needing disk IO.

Layout is still important, and leaving some blank space may not be so
crazy.  Here I'm thinking not so much of ordering (although one would
probably be best served by the recommended default ordering), but of
alignment, size, raid/stripe/concat configuration, and file system
block and fragment size selection.  Witness the (as much as tenfold)
performance difference from simple changes, highlighted in the recent
thread entitled 'File system blocks alignment' on freebsd-arch@ during
December 2009 - January 2010, beginning with:

If you're laying out a new disk, you may as well take a few minutes
and get the most out of it, even if you're not going to invest in a
lot of new hardware.


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