[lustre-discuss] confused about mdt space

肖正刚 guru.novice at gmail.com
Tue Mar 31 22:00:45 PDT 2020

Thanks a lot.
I have two more questions:
1) Assume I consider the mdt space use the method described in lustre
manual, by calculation, the metadata space is 400GB.
After format(default option), about 160GB(40% of 400GB) preallocated for
inodes, so the avalaible inodes number is less than estimated, right ?
2) mds need additional space for other use, like log,acls,xattrs;how to
estimate these space ?


Mohr Jr, Richard Frank <rmohr at utk.edu> 于2020年3月31日周二 下午9:57写道:

> > On Mar 30, 2020, at 10:56 PM, 肖正刚 <guru.novice at gmail.com> wrote:
> >
> > Hello, I have some question about metadata space.
> > 1) I have ten 960GB SAS SSDs for mdt,after done raid10,we have 4.7TB
> space free.
> > after formated as mdt,we only have 2.6TB space free; so where the 2.1TB
> space go ?
> > 2) for the 2.6TB space, what's it used for?
> That space is used by inodes.  I believe the recent lustre versions use a
> 1KB inode size by default and the default format options create 1 inodes
> for every 2.5 KB of MDT space.  So about 40% of your disk space will be
> consumed by inodes.
>> Rick Mohr
> Senior HPC System Administrator
> Joint Institute for Computational Sciences
> University of Tennessee
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