Date: Sat, 27 Apr 2002 22:08:56 -0400 From: parv <parv@pair.com> To: f-q <freebsd-questions@freebsd.org> Subject: understanding disk slicing & fs layout Message-ID: <20020428020855.GA3416@moo.holy.cow>
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i am preparing to repartition & re-slice my drive. currently i
have...
Filesystem 1K-blocks | Used Avail Capacity| iused ifree | waste/
| | | overhead
-----------------------|--------------------------|-----------------|----------
/dev/ad0s2a 496111 | 100109 356314 22% | 2060 122866 | 38.8 MB
/dev/ad0s2e 2083854 | 1654378 262768 86% | 72460 451314 | 162.8 MB
/dev/ad0s3f 2860982 | 1113524 1518580 42% | 124737 591613 | 223.5 MB
/dev/ad0s3e 714447 | 1 657291 0% | 1 179581 | 55.8 MB
/dev/ad0s2f 218463 | 193896 7090 96% | 1617 53037 | 17.1 MB
--------------------------------------------------------------------------------
total: 6373857 3061908 2802043 -- ------ ------ -----
total in MB: 6224.5 2990.1 2736.4 -- ------ ------ 498
calculated overhead factor, o = 12.5
usable = total - (total/o)
total = usable * o/(o - 1) ; 12.5/(12.5 - 1) = 1.08696
...as you can see the most obvious thing -- besides allocating around
130 MB to / & mounting /tmp as mfs -- to keep in mind for me is to
adjust the inode numbers. even when every slice is full, there will
still be plenty of inodes left unused.
it has been long time since i sliced disk, so during partitioning &
slicing disk, is the user asked about adjusting the inodes?
another question, how is the factor of 12.5 came about to be (other
than being a calculated quantity)? here is what newfs shows for
/dev/ad0s2a...
Warning: Block size and bytes per inode restrict cylinders per group to 90.
/dev/ad0s2a: 1024000 sectors in 250 cylinders of 1 tracks, 4096 sectors
500.0MB in 3 cyl groups (90 c/g, 180.00MB/g, 21120 i/g)
super-block backups (for fsck -b #) at:
32, 368672, 737312
...and, for /dev/ad0s2f ...
Warning: Block size restricts cylinders per group to 96.
Warning: 3808 sector(s) in last cylinder unallocated
/dev/ad0s2f: 450848 sectors in 111 cylinders of 1 tracks, 4096 sectors
220.1MB in 2 cyl groups (96 c/g, 192.00MB/g, 14080 i/g)
super-block backups (for fsck -b #) at:
32, 393248
(so far i had read newfs manpage, on to reading disklabel's again.)
thanks much.
- parv
ps: i will appreciate if just mail to -questions & not cc me. but
if you can't help yourself, i understand. (:
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