[lustre-discuss] Lustre Size Variation after formatiing

ANS ans3456 at gmail.com
Mon Aug 20 21:33:29 PDT 2018


Thanks Rick for your detailed info.

Can you please let me know what are the preferred standard benchmark tools
that i can use for testing the lustre like IOR and what is the result that
i can expect.

Thanks,
ANS.

On Tue, Aug 21, 2018 at 4:49 AM Mohr Jr, Richard Frank (Rick Mohr) <
rmohr at utk.edu> wrote:

>
> > On Aug 20, 2018, at 2:58 AM, ANS <ans3456 at gmail.com> wrote:
> >
> > 1) CentOS 7.4
> > 2) Lustre version 2.11
> > 3) MDT LUN Size is 6.5 TB (RAID 10) and after formatting using lustre we
> are getting the size as 3.9 TB, when formatted using XFS is showing
> accurate.
>
> For Lustre 2.10 and up, the default inode size is 1KB.  Unless you
> specifically pass different options to your mkfs command, it will create an
> inode for every 2.5KB of MDT space.  So the amount of free space will
> actually be 1.5KB/2.5KB = 60% of the total space.  For your MDT, 0.6 x
> 6.5TB = 3.9TB. That is the source of the size discrepancy.
>
> --
> Rick Mohr
> Senior HPC System Administrator
> National Institute for Computational Sciences
> http://www.nics.tennessee.edu
>
>

-- 
Thanks,
ANS.
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