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 was proposing to just have a boolean flag as parameter, something to the
effect of for-multi-read, the argument being redirector / server do not care why
certain servers are excluded.
Thinking about it, I'd still like to have a count of existing multi-source
sessions so the cmsd decision can be made based on both counts (failed and
multi-source). That would make the option integer, say, "existing_sources=N".
My head starts to spin trying to think what happens to tried= and
using=/existing_sources= when being redirected from, say, US redirector to
global one. Maybe original proposal is not so bad in this respect as the
"collapse on static redirect" already exists for tried= and would probably be
the same for using=.
Matevz
> 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
>>>
>>> ########################################################################
>>> Use REPLY-ALL to reply to list
>>>
>>> To unsubscribe from the XROOTD-DEV list, click the following link:
>>> https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=XROOTD-DEV&A=1
>>
>> ########################################################################
>> Use REPLY-ALL to reply to list
>>
>> To unsubscribe from the XROOTD-DEV list, click the following link:
>> https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=XROOTD-DEV&A=1
>>
>> ########################################################################
>> Use REPLY-ALL to reply to list
>>
>> To unsubscribe from the XROOTD-DEV list, click the following link:
>> https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=XROOTD-DEV&A=1
>>
########################################################################
Use REPLY-ALL to reply to list
To unsubscribe from the XROOTD-DEV list, click the following link:
https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=XROOTD-DEV&A=1
