Re: [ofa-general][PATCH 3/4] SRP fail-over faster

[Vu Pham <vuhuong-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>]

Roland Dreier wrote:
>  > >  > First it does not make sense for user to set it below 60; therefore,
>  > >  > it is forced to have 60 and above
>
>  > > Why not?  A minute seems to be a really long time given the point of
>  > > these patches is supposed to be failing over faster.  Surely we can tell
>  > > if a path really failed sooner than 60 seconds on an IB fabric.
>
>  > When we fail-over, it will cause the luns ownership transfer in
>  > target/storage. It's undesirable op unless necessary
>  > Target/storage most likely can reboot and come back within 60 seconds
>  > We don't want to create the situation of path bouncing
>
> OK, I can see why in some (many) situations it makes sense to wait a
> while before reporting a target as gone.  But why do we hard code the
> policy of a minimum timeout of 60 seconds in the kernel?  Why not a
> minimum of 120 seconds?  What if I know my storage is guaranteed to
> reboot in 2 seconds -- why can't I have a timeout of 5 seconds?
>
> You haven't really explained where the magic number of 60 seconds comes from.
>
>  - R.
>   
I don't have a clear answer. Same as why 30 secs for scsi to start 
aborting command(s).
I think 60 secs is not too long, not too short for a taget coming back 
online

-vu
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