the 10% factor

[Jeffery Bacon]

In article <2643 at auspex.auspex.com>, hitz at auspex.auspex.com (Dave Hitz) says:
>
>The problem is that as a file grows on a mostly full partition, the
>block immediately following the last one in the file is generally not
>available.  Even on almost empty files this is always a possibility,
>but statistically it turns out that only as the filesystem passes 90%
>full does this problem become nasty.
>

    How does one learn this stuff? I RTF(Sun)Ms, but it didn't help that much.
Or was I looking in the wrong place?

>
>Now the question about swap is interesting.  When you create a swap
>file using mkfile(8), it allocates disk blocks when the file is
>created.  If you create a 20 MB swap file in an otherwise empty 20 MB
>partition, the block allocation would probably be quite good because
>there would be no conflict with smaller chuncks of space being
>allocated in other files.  If you want more than one swap file per partition,
>that would probably work also, but make sure *not* to run the mkswap's in
>parallel.  Do them one after the other.  (And don't use the -n option which
>would defeat the whole point of getting the blocks nicely allocated at
>create time.)
>

     Well, I hate to sound too stupid, but I did just this on a couple of
swap partitions I made a couple of months ago. (Run the mkfile(8)s in
parallel. This is on a Sun 3/260, SunOS4.0.3, 2 280MB Fujitsu's, 3 ~36Mb
swaps on two 117MB partitions. The partitions are packed full, with about
500K free each.) Should I remake the swap files?
     At the same time, it occured to me to cut the number of inodes and the
size of the minfree value. After all, there are only 3 files...(plus the
. and .. directory)...I don't see anything wrong with having done that, am I
correct?

>--
>Dave Hitz                                       home: 408-739-7116
>UUCP: {uunet,mips,sun,bridge2}!auspex!hitz      work: 408-492-0900
-------
Jeffery Bacon
Computing Technology Svcs., Michigan Technological University
bitnet: bacon at mtus5  uucp (alternate): <world>!itivax!anet!bacos