On Wed, Jun 18, 2014 at 06:11:33AM -0400, Anjana Kar wrote: > ...... > Instead we have moved to ldiskfs MDT and zfs OSTs, with the same lustre/zfs > versions, and have a lot more inodes available. > > Filesystem Inodes IUsed IFree IUse% Mounted on > x.x.x.x@o2ib:/iconfs > 39049920 7455386 31594534 20% /iconfs
Since ZFS doesn't create [iz]nodes statically, in statfs it simply estimates the free inodes as availbytes >> 9, see zfs_statvfs(). So I'd guess that the difference in reported free inodes was caused by differences in space efficiency. I don't know about ldiskfs but two things come to mind about ZFS: 1. By default ZFS stores two copies (a.k.a. ditto blocks) of file system metadata, in addition to whatever replication the pool already has. As a result, unless ldiskfs does something similar, ZFS would be only 50% space efficient as ldiskfs, since the work load was mostly metadata. An easy way to verify this would be to compare the reported free space of ZFS and ldiskfs. 2. ZFS might be using a bigger sector size for the disks. Some drives report 512 bytes for compatibility while they are truly 4K, but ZFS has a built-in list of devices that lie to override the answer from the drives. This may also contribute to space efficiency of ZFS. -Isaac _______________________________________________ Lustre-discuss mailing list Lustre-discuss@lists.lustre.org http://lists.lustre.org/mailman/listinfo/lustre-discuss