From mboxrd@z Thu Jan 1 00:00:00 1970 From: imp@bsdimp.com (Warner Losh) Date: Mon, 23 Apr 2018 16:15:05 -0600 Subject: [TUHS] /dev/drum In-Reply-To: References: <8225C5DB-27BD-464E-930A-522C30C20EBD@tfeb.org> <25A1FED0-4F8B-408F-B27B-5728C649D8BE@collantes.us> <7wfu3nuqeb.fsf@junk.nocrew.org> <3A18DFEC-42B7-4234-9DD1-367733270D50@tfeb.org> <0abe01d3db28$b6573660$2305a320$@ronnatalie.com> Message-ID: On Mon, Apr 23, 2018 at 4:07 PM, Tim Bradshaw wrote: > On 23 Apr 2018, at 21:47, Grant Taylor via TUHS > wrote: > > 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. > 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: