[gpfsug-discuss] data integrity documentation

[Stijn De Weirdt]

hi sven,


> the very first thing you should check is if you have this setting set :
maybe the very first thing to check should be the faq/wiki that has this
documented?

> 
> mmlsconfig envVar
> 
> envVar MLX4_POST_SEND_PREFER_BF 0 MLX4_USE_MUTEX 1 MLX5_SHUT_UP_BF 1
> MLX5_USE_MUTEX 1
> 
> if that doesn't come back the way above you need to set it :
> 
> mmchconfig envVar="MLX4_POST_SEND_PREFER_BF=0 MLX5_SHUT_UP_BF=1
> MLX5_USE_MUTEX=1 MLX4_USE_MUTEX=1"
i just set this (wasn't set before), but problem is still present.

> 
> there was a problem in the Mellanox FW in various versions that was never
> completely addressed (bugs where found and fixed, but it was never fully
> proven to be addressed) the above environment variables turn code on in the
> mellanox driver that prevents this potential code path from being used to
> begin with.
> 
> in Spectrum Scale 4.2.4 (not yet released) we added a workaround in Scale
> that even you don't set this variables the problem can't happen anymore
> until then the only choice you have is the envVar above (which btw ships as
> default on all ESS systems).
> 
> you also should be on the latest available Mellanox FW & Drivers as not all
> versions even have the code that is activated by the environment variables
> above, i think at a minimum you need to be at 3.4 but i don't remember the
> exact version. There had been multiple defects opened around this area, the
> last one i remember was  :
we run mlnx ofed 4.1, fw is not the latest, but we have edr cards from
dell, and the fw is a bit behind. i'm trying to convince dell to make
new one. mellanox used to allow to make your own, but they don't anymore.

> 
> 00154843 : ESS ConnectX-3 performance issue - spinning on pthread_spin_lock
> 
> you may ask your mellanox representative if they can get you access to this
> defect. while it was found on ESS , means on PPC64 and with ConnectX-3
> cards its a general issue that affects all cards and on intel as well as
> Power.
ok, thanks for this. maybe such a reference is enough for dell to update
their firmware.

stijn

> 
> On Wed, Aug 2, 2017 at 8:58 AM Stijn De Weirdt <stijn.deweirdt at ugent.be>
> wrote:
> 
>> hi all,
>>
>> is there any documentation wrt data integrity in spectrum scale:
>> assuming a crappy network, does gpfs garantee somehow that data written
>> by client ends up safe in the nsd gpfs daemon; and similarly from the
>> nsd gpfs daemon to disk.
>>
>> and wrt crappy network, what about rdma on crappy network? is it the same?
>>
>> (we are hunting down a crappy infiniband issue; ibm support says it's
>> network issue; and we see no errors anywhere...)
>>
>> thanks a lot,
>>
>> stijn
>> _______________________________________________
>> gpfsug-discuss mailing list
>> gpfsug-discuss at spectrumscale.org
>> http://gpfsug.org/mailman/listinfo/gpfsug-discuss
>>
> 
> 
> 
> _______________________________________________
> gpfsug-discuss mailing list
> gpfsug-discuss at spectrumscale.org
> http://gpfsug.org/mailman/listinfo/gpfsug-discuss
>