[Lustre-discuss] Slow performance on the first IOR / iozone (Lustre)

[Brian J. Murrell]

On Tue, 2008-03-25 at 10:37 -0400, Oleg Drokin wrote:
>     You certainly can prefetch that data sooner as a workaround and  
> with zero kernel hacking
>     required by e.g. doing dumpe2fs on every device with lustre  
> backend fs after lustre servers
>     are started (it is important to do this after mount, since kernel  
> discards all block device data
>     on last device close).

Cédric,

If nothing else, you could use this technique to confirm Oleg's theory
that it is indeed bitmaps being cached that is resulting in your
performance observations.  Not that I doubt Oleg's expertise here.  It
would just be scientific data to confirm your situation.

b.

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