24 Apr
2018
24 Apr
'18
12:15 a.m.
On Mon, Apr 23, 2018 at 4:07 PM, Tim Bradshaw <tfb(a)tfeb.org> wrote:
On 23 Apr 2018, at 21:47, Grant Taylor via TUHS
<tuhs(a)minnie.tuhs.org>
wrote:
It's weird. These days lower LBAs perform better on spinning drives. We're
seeing about 1.5x better performance on the first 30% of a drive than on
the last 30%, at least for read speeds for video streaming....
Warner
I had always wondered where Solaris (SunOS) got
it's use of the
different slices, including the slice that was the entire disk
from.
Now I'm guessing Solaris got it from SunOS which got it from 4.x BSD.
There is a wonderful Sun cretinism about this. At some recent time (I am
not sure how recent but probably mid 2000s), someone worked out that you
wanted swap to be at one end of the disk (I think the outside) because on
modern disks the data rate changes across the disk and you wanted it at the
end with the highest data rate. But lots of things knew that swap was on
s1, the second partition. So they changed the default installation tool so
the slices of the disk were out of order: s1 was the first, s0 the second,
s2 was the whole disk (which it already was) and so on. This was
enormously entertaining in a bad way if you made the normal assumption that
the slices were in order. There was also (either then or before) some
magic needed such that swapping never touched the first n blocks of the
disk where the label and boot blocks were, and it was possible to get this
wrong so the machine would happily boot, run but would then fail to boot
again, usually at a most inconvenient time.
And the cretinism was that this was mid 2000s: if you had machine that
was paging the answer was to buy more memory not to arrange for faster swap
space: it was solving a problem that nobody had any more.