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Description
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In the output from fstyp -v on a ufs filesystem, the cylinder group superblocks
are printed thusly:
cg 0:
magic 90255 tell 6000 time Sun Oct 13 14:08:12 2002
cgx 0 ncyl 9 niblk 3328 ndblk 55296
nbfree 0 ndir 2153 nifree 0 nffree 0
rotor 528 irotor 3327 frotor 520
frsum 0 0 0 0 0 0 0
sum of frsum: 0
iused: 0-3327
[...]
The ``tell'' value is not part of the superblock, but rather the byte offset
into the partition of where the superblock starts. This value is printed as
a long (%lx) and has a corresponding cast to off_t. The actual variable is
an offset_t, which is 64 bits. With larger filesystems, the offset wraps as
far as print() is concerned, and the reported offsets are completely wrong.
This is, of course, merely a curiosity unless you are trying to look at the
raw filesystem and correlate it with fstyp's output. In that situation, the
odds are good it's being done to resolve some problem with the filesystem, at
which point it becomes a major tail-chaser.
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oss-bite-size
xxxxx@xxxxx.com 2005-06-25 11:09:52 GMT
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