Re: [PATCH 0/1] Enable inter server to server copies on a export

Steve Dickson
2021-11-01T19:03:02Z

On 11/1/21 11:40, J. Bruce Fields wrote:
> On Mon, Nov 01, 2021 at 11:30:48AM -0400, Steve Dickson wrote:
>> Hey!
>>
>> On 10/29/21 15:14, J. Bruce Fields wrote:
>>> On Fri, Oct 29, 2021 at 01:30:36PM -0400, Steve Dickson wrote:
>>>> On 10/29/21 12:40, J. Bruce Fields wrote:
>>>>> Let's just stick with that for now, and leave it off by default until
>>>>> we're sure it's mature enough. Let's not introduce new configuration to
>>>>> work around problems that we haven't really analyzed yet.
>>>> How is this going to find problems? At least with the export option
>>>> it is documented
>>>
>>> That sounds fixable. We need documentation of module parameters anyway.
>> Yeah I just took I don't see any documentation of module
>> parameters anywhere for any of the modules. But by documentation
>> I meant having the feature in the exports(5) manpage.
>
> I think I'd probably create a new page for sysctls (this isn't the only
> one needing documentation), and make sure it's listed in the "SEE ALSO"
> section of the other man pages.
>
>>>> and it more if a stick you toe in the pool verses
>>>> jumping in...
>>>
>>> If we want more fine-grained control, I'm not yet seeing the argument
>>> that an export option on the destination server side is the way to do
>>> it.
>>>
>>> Let's document the module parameter and go with that for now.
>> Now that cp will use copy_file_range() when available,
>> what are the steps needed to enable these fast copies?
>
> 1) Make sure client and both servers support NFSv4.2 and
> server-to-server copy.
Something is already figuring this out... The only time
the client sends a COPY_NOTIFY and COPY is when both
mounts are 4.2. I have not looked into but that is what
the network traces are showing.

>
> 2) Make sure destination server can access (at least for read) any
> exports on the source that you want to be able to copy from.
How can one server know what the other server has exported
or access to??

>
> 3) echo 1 >/sys/module/nfsd/parameters/inter_copy_offload_enable on the
> destination server.
Who would be doing this? Plus this would not survive over a reboot.
An export would as well a /etc/modprobe.d/ file.

I can see the admin setting up the export but I really
don't see the admin doing the echo or creating the file
esp since the neither would is documented.

steved.