I have a space and a backup (ndmp) issues with one of my volumes that is dedicated for mail in 'maildir' format (one message per file).

I'm looking for suggestions from people on alleviating the space issue and possibly suggestions on the ndmp backup of this volume. I'm thinking that these two might be related.

filer#1:/vol/maildir (14 x 72 GB disks) 2 qtrees: ugrad (undergrad students) grad (grad students)

backup: (nightly incr. on an average backs up about) 11GB , 6million files, runs for 7 hrs

filer#2:/vol/maildir2 (14 x 72 GB disks) 1 qtree: emp (employees) backup: (nightly incr. on an average backs up about) 8GB , 5million files, runs for 1.5 hrs

All 3 qtrees have the same 2 level directory tree structure (as suggested by NetApp) and a common hashing algorithm is used to create 'home directories' in these qtrees. The top directory contains sub-directories from 0-to-f. Each of those directories contain sub-directories ranging from 00-to-ff. So a persons home directory would be something like: /vol/maildir/grad/2/75/dummy

I need more space for the filer#1:/vol/maildir volume.

Q1: should I just expand the volume onto more disks ? having more spindles might speed up the backup ?

Q2: should I separate the 2 qtrees (u/grad) into their own volumes (14 x 72 GB each) to give each more space ? having only one qtree to scan , ndmp might run that much faster ?

Thanks for any suggestions. George