Hi Andy, Brian,
I'm trying to create a ticket for CMSSW XrdAdaptor to use triedrc=.
For xcache redirector, it is clear one should use =triedrc=resel (local
reselection).
With XrdAdaptor this will become the default for other multi-source requests ...
and will thus solve FNAL issue, if the jobs talk to the local FNAL redirector.
1. Brian: how should we introduce the option for =triedrc=reseg (global
reselection) into XrdAdaptor? Should this come from outside in some fashion,
like an env var?
2. Andy: I was tracing through the code to remember how this is all done and
noticed that kYR_tryRSEG never gets used in the code (other than for definition
and for setting it when reseg is given). Is there something missing here or I
just don't get the whole global reselection thing (again)?
Matevz
On 2019-05-09 15:36, Andrew Hanushevsky wrote:
> Hi Brian,
>
> OK, you got you wish along with a way to bypass it (the default being "keep it
> local"). Now, are you going to be at the XRootD Workshop? If not, can someone be
> there to give a presentation on the latest developments on SciTokens et al?
>
> Andy
>
> -----Original Message----- From: Bockelman, Brian
> Sent: Monday, May 06, 2019 1:39 AM
> To: Andrew Hanushevsky
> Cc: Matevz Tadel ; Michal Kamil Simon ; xrootd-dev
> Subject: Re: Proposal for new opaque URL parameter using= complementing tried=
>
> Hi Andy,
>
> In this case - there's good reason to not send clients offsite (even if the
> offsite server is providing better performance, the WAN costs more...) when
> there's a perfectly good copy onsite. We can be sure to drop the "resel" from
> the "triedrc" when the job is looking for an additional source because of an
> error instead of wanting faster sources.
>
> I think it would be useful to keep the "file not found" code to only trigger
> when the file is actually not found.
>
> Brian
>
>> On May 6, 2019, at 7:35 AM, Andrew Hanushevsky <[log in to unmask]> wrote:
>>
>> Well, isn't the point of reselection is to find the best possible site which
>> could be offsite? We could give you an option to keep it local but you would
>> need to add that to the conig file.
>>
>> On Sun, 5 May 2019, Bockelman, Brian wrote:
>>
>>> Hi Matevz,
>>>
>>> The other thing that should go into the cmsd is to avoid doing a ?redirect on
>>> file not found? for reselection.
>>>
>>> This would help immensely in cases like FNAL which uses this for all jobs,
>>> causing the multi source CMSSW to pull data that is onsite, from offsite, due
>>> to reselection.
>>>
>>> (After telling them for 5 years to change, I guess we can tweak the software
>>> ;) )
>>>
>>> Brian
>>>
>>> Sent from my iPhone
>>>
>>>> On May 3, 2019, at 6:57 PM, Matevz Tadel <[log in to unmask]> wrote:
>>>>
>>>> Hi,
>>>>
>>>> Andy realized that an option for this already exists -- triedrc=resel
>>>>
>>>> Andy impleented a change in cmsd that allows disabling opening of a new file
>>>> on reselection, goes under cmsd.sched nomultisrc.
>>>>
>>>> Brian, now we have to propagate this into XrdAdapter.
>>>>
>>>> Matevz
>>>>
>>>>> On 4/18/19 10:45 AM, Andrew Hanushevsky wrote:
>>>>> After some discusion with Matevz, we decided to simplify this, So, it won't
>>>>> be exactly what was outlined but will be functionally the same. This
>>>>> requires soem development in the cmsd. That said, an issue should be cut.
>>>>> Andy
>>>>>> On Thu, 18 Apr 2019, Michal Kamil Simon wrote:
>>>>>> Hi,
>>>>>>
>>>>>> It sounds reasonable to me :-)
>>>>>>
>>>>>> Matevz: could you create an issue in github so we don't loose
>>>>>> track of this topic? ;-)
>>>>>>
>>>>>> Cheers,
>>>>>> Michal
>>>>>> ________________________________________
>>>>>> From: [log in to unmask] [[log in to unmask]] on
>>>>>> behalf of Bockelman, Brian [[log in to unmask]]
>>>>>> Sent: 17 April 2019 03:59
>>>>>> To: [log in to unmask]
>>>>>> Cc: xrootd-dev
>>>>>> Subject: Re: Proposal for new opaque URL parameter using= complementing
>>>>>> tried=
>>>>>>
>>>>>> Yes! We definitely could benefit from this on the CMS side!
>>>>>>
>>>>>> Sent from my iPhone
>>>>>>
>>>>>>> On Apr 15, 2019, at 5:21 PM, Matevz Tadel <[log in to unmask]> wrote:
>>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> [This is mostly for Andy, Brian, and Michal.]
>>>>>>>
>>>>>>> In the context of XCache cluster used by CMSSW multi-source jobs there is
>>>>>>> an issue with cmssw jobs requesting opening of a second source on the
>>>>>>> cache cluster using the tried= opaque parameter to point to cache server
>>>>>>> already in use. This leads to creation of another replica of the same
>>>>>>> file in the cache cluster.
>>>>>>>
>>>>>>> The cache still needs to honor tried= in case there is a problem with the
>>>>>>> existing server. However, asking for a new "extra" server in the context
>>>>>>> of cache does not make much sense.
>>>>>>>
>>>>>>> To distinguish these two conditions I propose to introduce a new opaque
>>>>>>> directive, "using=", used to signal to the redirector that the client is
>>>>>>> already using the listed servers.
>>>>>>>
>>>>>>> On cmsd side this would be accompanied with a cms.dfs multisource count
>>>>>>> ("sister" option to cms.dfs retries). These two would then control how
>>>>>>> many errors and parallel accesses are allowed for a client session.
>>>>>>>
>>>>>>> Does this make sense?
>>>>>>>
>>>>>>> Matevz
>>>>>>>
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>>>>
>>>
>
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