a bit of FFS questions

[Wojciech Puchar]

can someone help me.


1) newfs -a <more than 16> successfully creates the filesystem but dumpfs 
shows:

.
.
.
maxbsize 16384  maxbpg  2048    maxcontig 16    contigsumsize 16

what's the difference between maxcontig and contigsumsize?

will FreeBSD kernel actually make user of maxcontig >16 (with MAXPHYS>128k 
it make sense)

2) -b <more than 16384> - does it make real sense? i tested with large 
files and it CPU load is small anyway, while transfer speed is the same.

the answer may depend on answer for question 1 however.

3) -i <large value> - it would save space to use -i 16384, 32768 or more, 
and reduce fsck times.

but if inode counts is closely tailored to amount of files, will it slow 
down filesystem and how much?

i think if something like half or less inodes are allocated, OS have 
higher degree of freedom of where to allocate inode. but i imagine too 
that having even more free inodes doesn't make things.


what is the ratio  of used to free inodes, below which there will be just 
wasted space?

4) -o space/time - in my tests i can't see much difference in CPU load, 
maybe on 386 it was a difference but not on Athlon64 or P4.

isn't -o space better to be always used?

5) -m <low percents> - does -m change anything in FFS algorithms, or 
it's just a quota? i would prefer to set it low just in case of urgent 
need of space, while trying to maintain 8-10 free space at normal 
operation.

am i right?