[gpfsug-discuss] Rewriting existing files is incredibly slow

[Peter Hruška]

Hello,

We've encountered yet another performance flaw. We have a GPFS filesystem mounted using GPFS binaries on Windows. When we try to rewrite a file on the GPFS filesystem rewriting speed is much slower than writing to a new file. The difference ratio we measured is about 3.5 times. From the task manager it is visible that there is excessive amount of reading from the network when rewriting. This is even visible on the NDS server as io activity. However when rewriting on a linux client there are no reads while rewriting. Has anyone encountered such problems?
To replicate the issue is is possidle to run fio twice with the same configuration to achieve rewriting or to run iozone. Both tools return similar outputs.

--

S přáním pěkného dne / Best regards

Mgr. Peter Hruška
IT specialista

M Computers s.r.o.
Úlehlova 3100/10, 628 00 Brno-Líšeň (mapa<https://mapy.cz/s/gafufehufe>)
T:+420 515 538 136
E: peter.hruska at mcomputers.cz<mailto:peter.hruska at mcomputers.cz>

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