[Lustre-discuss] bad 1.6.3 striped write performance

[Johann Lombardi]

On Mon, Nov 26, 2007 at 08:39:58AM -0500, Robin Humble wrote:
> Hi,
> 
> I'm seeing what can only be described as dismal striped write
> performance from lustre 1.6.3 clients :-/
> 1.6.2 and 1.6.1 clients are fine. 1.6.4rc3 clients (from cvs a couple
> of days ago) are also terrible.
> 
> the below shows that the OS (centos4.5/5) or fabric (gigE/IB) or lustre
> version on the servers doesn't matter - the problem is with the 1.6.3
> and 1.6.4rc3 client kernels with striped writes (although un-striped
> writes are a tad slower too).
> 
> with 1M lustre stripes:
>    client              client                     dd write speed (MB/s)
>      OS                kernel                     a)    b)    c)    d)
> 1.6.2:
>   centos4.5  2.6.9-55.0.2.EL_lustre.1.6.2smp     202   270   118   117
>   centos5    2.6.18-8.1.8.el5_lustre.1.6.2rjh    166   190   117   119
> 1.6.3+:
>   centos4.5  2.6.9-55.0.9.EL_lustre.1.6.3smp      32     9    30     9
>   centos5    2.6.18-53.el5-lustre1.6.4rc3rjh      36    10    27    10
>                                                        ^^^^        ^^^^
>                                          yes, that is really 9MB/s. sigh

Could you please try to disable checksums?
On the client side:
for file in /proc/fs/lustre/osc/*/checksums; do echo 0 > $file; done

Johann