I want my i-nodes

William Roberts liam at cs.qmw.ac.uk
Tue Dec 4 01:43:02 AEST 1990


In <1990Nov28.150821.398 at wiskit.pdx.com> herbw at wiskit.pdx.com (Herb Weiner) 
writes:

>Now I wonder whether there is a better way.  Is a blocksize of 4096
>(the minimum allowable with BSD file systems on A/UX) wasteful for
>a news spool partition?

No, 4096 for a block isn't wasteful, because BSD filesystems actually 
allocate space for a file as (N Blocks + M "frags") where the frag size is 
smaller than the block size: it defaults to 1024 bytes, so a 2000 byte file 
would be allocated as 0 blocks + 2 frags. There are extra free-lists for 
different sized contiguous free frag groups (1 frag, 2 frags or 3 frags).
I have heard it said that smaller block sizes were a good thing for /tmp 
filestores - A/UX doesn't provide the bsd "dumpfs" utility which would tell
you more about the BSD filesystem that you could ever have wished to know, 
including what sizes you everr got.

For what it's worth, the bytes-per-inoe figure can be increased: my root
partition is small and has lots of large files, so I increased to to help 
squeeze in a few more Kbytes whilst still leaving space for a whole spare 
kernel (autoconfig - I hate you!). Df says:

% df -t /
/          /dev/dsk/c0d0s0          1459 blocks    1000 i-nodes
                         total    19823 blocks    1920 i-nodes

So that must be about 5k per inode...? Maybe it didn't work after all?
>I look forward to hearing how others have solved this problem.

>Herb Weiner (herbw at wiskit.pdx.com)
--

William Roberts                 ARPA: liam at cs.qmw.ac.uk
Queen Mary & Westfield College  UUCP: liam at qmw-cs.UUCP
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