We found a session.save_path depth of 3 led to excessive wastage of inodes and in fact disk space in storing the directory tree. dir_indexes option on ext2/3/4 makes larger directories more feasible anyway, so we decided to move to a depth of 2 instead.
It took a little puzzling to figure out how to move the existing PHP sessions up one directory tree, but we ended up running this in the root sessions directory:
#!/bin/sh
for a in ./* ; do
cd ./$a
pwd
for b in ./* ; do
cd ./$b
pwd
# Move existing sessions out
find ./* -xdev -type f -print0 | xargs -0 mv -t .
# Remove subdirectories
find ./* -xdev -type d -print0 | xargs -0 rmdir
cd ..
done
cd ..
done
This script may not be the best way to do it, but it got the job done fast. You can modify it for different depths by adding or removing "for" loops.
The documentation gives a depth of 5 as an example, but five is right out. If you're going beyond 2, you're at the scale where you may want to to look at a large memcached or redis instance instead.
