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Date:      Mon, 2 Apr 2001 02:31:51 -0500
From:      Andrew Hesford <ajh3@chmod.ath.cx>
To:        FreeBSD-questions <freebsd-questions@freebsd.org>
Subject:   disklabel and block size
Message-ID:  <20010402023151.A817@cec.wustl.edu>

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I have two related questions:

1. In the disklabel output, what is the significance of the bps/cpg
group? The man page for disklabel says that for disks larger than 1G, it
defaults to 64, but mine is 16, and an example in the man page had it
set at 75. What does this field mean, and how will different values
affect the disk?

2. All my filesystems have block sizes of 8k and fragment sizes of 1k.
What does this mean? For ext2 and fat, a block is the smallest
allocatable disk segment, meaning that I can store at most 1 file in
each 8k block. However, the fragment suggests that the smallest
allocatable segment is 1k, with block having a different meaning. Can I
store up to 8 files in each 8k data segment, or only 1 file?
Furthermore, if the fragment is the smallest allocatable group (in the
sense of an ext2 block), what is the significance of an FFS block? Is it
the amount of space that is reserved for file writing in order to prevent
fragmentation of data?
-- 
Andrew Hesford
ajh3@chmod.ath.cx

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