[Lustre-discuss] number of inodes in zfs MDT

[Dilger, Andreas]

On 2014/06/03, 6:37 PM, "Anjana Kar" <kar at psc.edu> wrote:

>Is there a way to set the number of inodes for zfs MDT?

No.  ZFS can create inodes until the filesystem is full.

>I've tried using --mkfsoptions="-N value" mentioned in lustre 2.0
>manual, but it fails to accept it.

This is an ldiskfs-specific option.

> We are mirroring 2 80GB SSDs for the MDT, but the number of inodes is
>getting set to 7 million, which is not enough for a 100TB filesystem.

Since the "free" inode count is just an estimate for ZFS, and is quite a
big guess when the filesystem is new, but gets more accurate as the
filesystem has more inodes created.  For 80GB SSDs with about 2KB/inode
(usable space) you might get at most about 20M inodes for such a
filesystem.

Cheers, Andreas
-- 
Andreas Dilger

Lustre Software Architect
Intel High Performance Data Division