John Hascall <[EMAIL PROTECTED]> writes:
> When you create a filesystem a portion of it is set aside (by default, 10%)
> and can only be used by root. So if you have a filesys with a nominal size
> of 55648KB, then 5565KB is "reserved", leaving you with 50083KB usable.
> It has been my experience that you can set your cachesize very close to
> this number (99% for example, 49582).
This is just a coincidence. Since AFS runs in the kernel, it can use
the entire partition. The disk space utilization calculations in the
cache manager don't take into account the sizes of CacheItems and
VolumeItems files, or the AFSLog if it's there. Those last three are
the reason you need some padding (or if you are using a filesystem
with a frag size > 1K in AFS < 3.2)
> I have a very small disk (104MB)
> on my workstation, so here are some of the things I found which could give
> me more AFS cache (your mileage may vary)... I checked the number of inodes
> used with "df -i" and found it never went above 22% so I recreated my
> cache filesystem with half as many inodes and only a 5% disk reserve (as
> described in "man newfs") and set my cache size to 99% of the resulting
> size (it was 90% of the old size). This raised my cache from ~18MB to ~30MB.
This is a good idea. (the % reserve is a red herring, tho' -- see
above). The cache partition requires an inode for each V-file (each
chunk), one for the CacheItems file, one for the VolumeItems file, one
for the AFSLog (default location in 3.1b), one for the filesystem
root, and one or two for safety. If you always run AFS with (eg) a 40
MB cache with -files 3000, you could recreate your cache filesystem
with 3010 inodes, and recover a bit of space. But don't try to
subsequently bump up -files without recreating the filesystem, or
you'll run into trouble.
The great thing about newfs'ing cache partitions is that you don't
have to back them up first.
WARNING: children under the age of 12 should not attempt this without
an adult present.
Lyle Transarc 707 Grant Street
412 338 4474 The Gulf Tower Pittsburgh 15219
