[Lustre-discuss] Performance versus allocation balance(?)

[Frank Heckes]

Hi Andreas,

many thanks for your detailed answer.


> Do you have imbalanced free space on the OSTs?  If yes, how much and do
> you know why it got imbalanced in the past?
>
The allocation varies from 65 - 70% usage per OST. The mean was 67%. So
definitely no difference > 25%.


> > Does anyone can confirm this observation?
> >
> > Is this really a 'feature' of Lustre and if so are there plans to
> > 're-design' the object allocation part, so that
> >
> > -a- full bandwidth can be reached with help of RR
>
> There is a bug open that discusses how to improve the OST space balancing
> using the round-robin allocator to avoid the dramatic performance loss
> that you are seeing.  In https://bugzilla.lustre.org/show_bug.cgi?id=18547
> there is a discussion of the issues and possible solutions, but work has
> not progressed recently.
>
I'll check the bugzilla ticket, to find out whether there's a solution
for our problem.

Many thanks.

Cheers

-Frank



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