[lustre-discuss] Writing to a single big file is slower

[Kal Alfizah]

Hello,


Doing IOR on single node to lustre fs. And notice write to a big single file is slower. I would think write to many small files will be slower. Any ideas why is it? And if there is any lustre setting able to fix it. It's lustre-2.10.4.


# mpirun -np 32  /temp/ior/bin/ior -a POSIX -C -v -w -k -F -i 1 -t 1m -b 8G -o /mnt/lustrefs/begdon/test2/eachfile-256G

...

Max Write: 4495.70 MiB/sec (4714.08 MB/sec)
...

# mpirun -np 32 /temp/ior/bin/ior -a POSIX -C -v -w -k -i 1 -t 1m -b 8G -o /mnt/lustrefs/begdon/test2/bigfile-256G
...
Max Write: 1331.97 MiB/sec (1396.67 MB/sec)
...

Thanks,
Kal

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