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

[Cédric Lambert]

Hello,

I am not today a kernel hacker ;-) and I would like to understand 
something :
Does it mean that when Lustre client is mounted, I am obliged to make 
any IOs to force bitmaps cache or am I obliged to wait a certain time 
before making any writes ? If Yes, can I monitor under /proc this info ?

Thanks
Cédric


Oleg Drokin a écrit :
>
> I believe what you are seeing is a direct result of bitmap blocks  
> being not
> read at mount time. So it takes some time to cache bitmaps (And other
> data structures) into memory
> (and it happens during writes which hinders performance).
> Once bitmaps are all read, performance stabilizes.
>
> Hopefully Alex or Andreas might comment further on this, or perhaps  
> remember
> a bug number, Cray filed one some time ago, I think.
>
> Bye,
>      Oleg
>