Date: Thu, 16 Sep 2004 14:02:38 -0500 (EST) From: Sam <sah@softcardsystems.com> To: Gary Corcoran <garycor@comcast.net> Cc: freebsd-hackers@freebsd.org Subject: Re: ZFS Message-ID: <Pine.LNX.4.60.0409161401110.28550@athena> In-Reply-To: <4149D73C.5030309@comcast.net> References: <41483C97.2030303@fer.hr> <Pine.LNX.4.60.0409151047230.21034@athena> <Pine.GSO.4.61.0409161010020.29724@mail.ilrt.bris.ac.uk> <Pine.GSO.4.61.0409161528520.29724@mail.ilrt.bris.ac.uk> <4149D73C.5030309@comcast.net>
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On Thu, 16 Sep 2004, Gary Corcoran wrote: > Sam wrote: > >> On Thu, 16 Sep 2004, Jan Grant wrote: >> >>> On Thu, 16 Sep 2004, Sam wrote: >>> >>>> Let's suppose you generate an exabyte of storage per year. Filling a >>>> 64-bit >>>> filesystem would take you approximately 8 million years. >>> >>> >>> Hang on, I'm not sure I know where these numbers are coming from. >>> >>> 1PB is - what? 2^50 bytes? That looks closer to 2^64 than your >>> figures indicate. I'd imagine an exabyte a year ought to be topping out >>> after 16 years. I'm missing about half-a-dozen orders of magnitude >>> somewhere it seems. >> >> >> 1PB is indeed 2^50 bytes, but filesystems don't address on the byte, >> but on the block (1K, 4K, 8k, ...). The numbers I'm using assume >> the filesystem addresses on the sector, which is unrealistically >> small. Jack it up to a 16K blocksize and you jump a few hundred >> ZB in size. > > You have to be able to *seek* on a byte boundary. Hence doesn't a > "64-bit" filesystem indeed mean "only" 2^64 bytes? Only for the file you're seeking on. Sam
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