[lustre-discuss] stuck combined mgs/mdt server when an ost is disabled

[Fernando Perez]

Hi.

I have migrated our lustre filesystem from 2.4 to 2.8 release two weeks 
ago and all works very well.

Now I need to migrate one OST due to hardware updates.

First I disabled the OST using lctl deactivate in the metadata server 
and then I executed lfs_migrate in a client, but it ran very very slow.

I discovered that when I disabled the ost the workload was very high, 
increases from 1 to 30, in the mdt/mgs server and the write operations 
in the lustre filesystem are very slow. Seems that there is a pause 
between you try to run the write operation and the operation is performed.

Finally if I turn to enable again the OST, previously disabled, lustre 
filesystems turns to work normally.

What could be the problem?

Regards.

-- 
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Fernando Pérez
Institut de Ciències del Mar (CMIMA-CSIC)
Departament Oceanografía Física i Tecnològica
Passeig Marítim de la Barceloneta,37-49
08003 Barcelona
Phone:  (+34) 93 230 96 35
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