[lustre-discuss] confused about mdt space

肖正刚 guru.novice at gmail.com
Wed Apr 1 08:50:14 PDT 2020


Now, I am clear.
Thanks Richard !

Mohr Jr, Richard Frank <rmohr at utk.edu> 于2020年4月1日周三 下午10:59写道:

>
>
> > On Apr 1, 2020, at 10:07 AM, Mohr Jr, Richard Frank <rmohr at utk.edu>
> wrote:
> >
> >
> >
> >> On Apr 1, 2020, at 3:55 AM, 肖正刚 <guru.novice at gmail.com> wrote:
> >>
> >> For  " 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" :
> >> I checked the inode size is 1KB and  in my online systems,  as you said
> , about 40~41% of mdt disk space consumed by inodes.
> >> but from the manual I found the default "inode ratio" is 2K, so where
> the additional 0.5KB comes from ?
> >>
> >
> > I was basing this on info I found in this email thread:
> >
> >
> http://lists.lustre.org/pipermail/lustre-discuss-lustre.org/2018-February/015302.html
> >
> > I think the 2K/inode ratio listed in the manual may be incorrect (or
> perhaps someone can point out my mistake).
>
> Looking at the lustre source (utils/libmount_utils_ldiskfs.c), the default
> behavior is determined by this line:
>
>                 bytes_per_inode = inode_size + 1536
>
> So the default bytes per inode is 1K (inode size) + 1.5K = 2.5K
>
>> Rick Mohr
> Senior HPC System Administrator
> Joint Institute for Computational Sciences
> University of Tennessee
>
>
>
>
>
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