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From: terry@cs.weber.edu (A Wizard of Earth C)
Subject: Re: Dumb Question: Why 512 byte block?
Message-ID: <1992Dec20.030146.279@fcom.cc.utah.edu>
Sender: news@fcom.cc.utah.edu
Organization: University of Utah Computer Center
References: <1992Dec18.030833.7395@fcom.cc.utah.edu> <1gt736INNjje@menudo.uh.edu> <1992Dec18.235623.27538@fcom.cc.utah.edu> <BzIEv1.G7G@pix.com>
Date: Sun, 20 Dec 92 03:01:46 GMT
Lines: 34
In article <BzIEv1.G7G@pix.com>, stripes@pix.com (Josh Osborne) writes:
|> In article <1992Dec18.235623.27538@fcom.cc.utah.edu> terry@cs.weber.edu (A Wizard of Earth C) writes:
|> [...]
|> >>If you have 6 1.5K files using 1K blocks,
|> >> 6 1k blocks will take each 1K from each file, and
|> >> 3 1k blocks will take 0.5k from each file.
|> >>This was my understading from the famous FUFS paper.
|> >
|> >You can't split blocks between files. A block is, by definition, the
|> >smallest possible allocation unit. Thin about the case where you have
|>
|> Under the FFS the fragment is the smallest allocation unit, and fragments are
|> only allocated at the end of a file. The rest of the file is in blocks.
[ ... ]
|> I think the BSD FFS is normally configured with 8K blocks, and 1K fragments,
|> or 4K blocks and 512b fragments. So the figures for 1.6K files you gave
|> are correct for the 4K/512b system, and low for the 8K/1K system. However
|> I don't think anything prevents you from having a 1K/128b filesystem (except
|> the block device drivers for disks, and mabie the buffer cache).
Yup. I mixed up frags and blocks. The "df" command (original poster's topic)
reports in "512-blks" ... the source of my confusion.
Terry Lambert
terry@icarus.weber.edu
terry_lambert@novell.com
---
Any opinions in this posting are my own and not those of my present
or previous employers.
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