Re:Lessons from Ancient File Systems
by antonkochubey on Monday July 29, 2024 @03:18PM
(#41102926)
Windows XP lived thorough 6 GB (minimum requirement - 1.5 GB, but I don't recall seeing drives less than six gigs at the time) to 2 TB HDD's. That's literally a 333x increase, which NTFS handled just fine. From min requirement it'd be a 1000x increase.
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> That's literally a 333x increase
Yet that's only going from 2^32 to 2^40.
Windows XP's default clustering (well, until SP2 at least) "only" allowed for 128GB disks. The cluster size was later increased. The 2TB limit was generally a limit for the BIOS code rather than an OS limit, as NTFS will happily scale beyond 2TB.
Windows NT 4 already contained the code necessary to allow for up to 16 exabyte partitions (https://web.archive.org/web/20010208131204/http://support.mi...), but the hardware it was running on probably didn't support anything bigger than a few terabytes. Sure, every text file takes up at least 2MB, but with an exabyte disk, you probably don't care about wasting sectors like that.
a system that can be scaled 333x or pushed into radically different allocation patterns by changing one or two constants seems like an odd choice for arguing that YAGNI and you shouldn't plan for anything beyond 10x/should plan for a system rearchitecture at that scale. That seems very much like a system that thought ahead and picked meaningful knobs to allow drastic changes in use-case to suit the situation.
When XP came out, you already had 100 GB consumer drives on the market that it had to support out of the box, so that's where I'd put the design requirements "starting point". That makes it only one order of magnitude bigger, similar to the 10x.