[lustre-discuss] zfs -- mds/mdt -- ssd model / type recommendation

[Isaac Huang]

The dnodes are stored in data blocks of the meta_dnode, whose block
size is a fixed constant:
#define DNODE_BLOCK_SHIFT       14      /* 16k */

Again, this is not affected by ZFS recordsize.

-Isaac

On Wed, May 06, 2015 at 09:02:11PM -0600, Isaac Huang wrote:
> On Tue, May 05, 2015 at 05:16:14PM +0000, Alexander I Kulyavtsev wrote:
> > ......
> > Shall we use smaller ZFS record size on MDT, say 8KB or 16KB? If inode is ~10KB and zfs record 128KB, we are dropping caches and read data we do not need.
> 
> The ZFS recordsize does not affect Lustre OST/MDT. The Lustre osd-zfs
> driver sets block sizes for its objects regardless of the ZFS
> recordsize. See:
> https://jira.hpdd.intel.com/browse/LU-4865
> https://jira.hpdd.intel.com/browse/LU-5391
> 
> -Isaac
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-- 
-Isaac