Lustre 1.6 Operations Manual

33.9 MDS Space Consumption
A single MDS imposes an upper limit of 4 billion inodes. The default limit is slightly
less than the device size of 4 KB, meaning 512 MB inodes for a filesystem with MDS
of 2 TB. This can be increased initially, at the time of MDS filesystem creation, by
specifying the --mkfsoptions='-i 2048' option on the --add mds config line
for the MDS.
For newer releases of e2fsprogs, you can specify '-i 1024' to create 1 inode for
every 1KB disk space. You can also specify '-N {num inodes}' to set a specific
number of inodes. The inode size (-I) should not be larger than half the inode ratio
(-i). Otherwise, mke2fs will spin trying to write more number of inodes than the
inodes that can fit into the device.
For more information, see Options to Format MDT and OST Filesystems.
33.10 Maximum Length of a Filename and
Pathname
This limit is 255 bytes for a single filename, the same as in an ext3 filesystem. The
Linux VFS imposes a full pathname length of 4096 bytes.
33.11 Maximum Number of Open Files for
Lustre Filesystems
Lustre does not impose maximum number of open files, but practically it depends
on amount of RAM on the MDS. There are no "tables" for open files on the MDS, as
they are only linked in a list to a given client's export. Each client process probably
has a limit of several thousands of open files which depends on the ulimit.
33-4 Lustre 1.6 Operations Manual • September 2008