Lustre 1.6 Operations Manual

How do I set striping for a large number of files at one time?
You can set a default striping on a directory, and then any regular files created
within that directory inherit the default striping configuration. To do this, first create
a directory if necessary and then set the default striping in the same manner as you
do for a regular file:
lfs setstripe -1
If the stripe_size value is zero (0), it uses the system-wide stripe size. If the
stripe_count value is zero (0), it uses the default stripe count. If the stripe_count
value is -1, it stripes across all available OSTs. The best performance for many clients
writing to individual files is at 1 or 2 stripes per file, and maximum stripes for large
shared-I/O files (i.e. many clients reading or writing the same file at one time).
If I set the striping of N and B for a directory, do files in that directory
inherit the striping or revert to the default?
All new files get the new striping parameters, and existing files will keep their
current striping (even if overwritten). To "undo" the default striping on a directory
(to use system-wide defaults again) set the striping to "0 -1 0".
Appendix D Lustre Knowledge Base D-9