ndctl: 10G not a multiple of 2M?

ndctl: 10G not a multiple of 2M?

[Linda Knippers]

Hi Dan,

I was creating a namespace on a 4-way interleave set and got an error
I didn't expect:

$ sudo ndctl create-namespace -m sector -s 10G -n number2
  Error: '--size=' must align to interleave-width: 4 and alignment: 2097152
  did you intend --size=12G?

I think there's a bug in validate_namespace_options().

What's happening is that since I specified my size in units of G,
the function wants the namespace to be 1G * 4 aligned rather than
2M * 4 aligned.  I suspect if I specified my size in M, it would
have worked but I can't test that at the moment.

>  size_align = max(units, size_align) * ways;

Why is units part of the equation?

-- ljk
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Re: ndctl: 10G not a multiple of 2M?

[Dan Williams]

On Wed, Jul 26, 2017 at 11:47 AM, Linda Knippers <linda.knippers@hpe.com> wrote:
> Hi Dan,
>
> I was creating a namespace on a 4-way interleave set and got an error
> I didn't expect:
>
> $ sudo ndctl create-namespace -m sector -s 10G -n number2
>   Error: '--size=' must align to interleave-width: 4 and alignment: 2097152
>   did you intend --size=12G?
>
> I think there's a bug in validate_namespace_options().
>
> What's happening is that since I specified my size in units of G,
> the function wants the namespace to be 1G * 4 aligned rather than
> 2M * 4 aligned.  I suspect if I specified my size in M, it would
> have worked but I can't test that at the moment.
>
>>  size_align = max(units, size_align) * ways;
>
> Why is units part of the equation?

Good question, looks like a blatant thinko to me. I think we're good to just do:

    size_align *= ways;

However, I still want to make the recommendation in terms of the units
specified for --size, but that calculation should come after the base
alignment check.
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