[lustre-discuss] The confusion for mds hardware requirement

[Amin Brick Mover]

Hi,  Andreas.

Thank you for your reply.

Can I consider 256 files per core as an empirical parameter? And does the
parameter '256' need testing based on hardware conditions? Additionally, in
the calculation formula "12 interactive clients * 100,000 files * 2KB =
2400 MB," is the number '100,000' files also an empirical parameter? Do I
need to test it. Can I directly use the values '256' and '100,000'?

Andreas Dilger <adilger at whamcloud.com> 于2024年3月11日周一 05:47写道：

> These numbers are just estimates, you can use values more suitable to your
> workload.
>
> Similarly, 32-core clients may be on the low side these days.  NVIDIA DGX
> nodes have 256 cores, though you may not have 1024 of them.
>
> The net answer is that having 64GB+ of RAM is inexpensive these days and
> improves MDS performance, especially if you compare it to the cost of
> client nodes that would sit waiting for filesystem access if the MDS is
> short of RAM.  Better to have too much RAM on the MDS than too little.
>
> Cheers, Andreas
>
> On Mar 4, 2024, at 00:56, Amin Brick Mover via lustre-discuss <
> lustre-discuss at lists.lustre.org> wrote:
>
> In the Lustre Manual 5.5.2.1 section, the examples mentioned:
>
> *For example, for a single MDT on an MDS with 1,024 compute nodes, 12
> interactive login nodes, and a*
> *20 million file working set (of which 9 million files are cached on the
> clients at one time):*
> *Operating system overhead = 4096 MB (RHEL8)*
> *File system journal = 4096 MB*
> *1024 * 32-core clients * 256 files/core * 2KB = 16384 MB*
> *12 interactive clients * 100,000 files * 2KB = 2400 MB*
> *20 million file working set * 1.5KB/file = 30720 MB*
>
> I'm curious, how were the two numbers, 256 files/core and 100,000 files,
> determined? Why?
>
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>
>
> Cheers, Andreas
> --
> Andreas Dilger
> Lustre Principal Architect
> Whamcloud
>
>
>
>
>
>
>
>
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