Hi Doug,
The specific is that you need not call anything in the ofs and neither
does Alja as all that just happens in the course of doing file operations.
The link that I gave you explains in detail what the script gets and
whatto put in he configuration file to make that happen. Now that I think
more about it, it's likely it won't solve the whole issue because the
caching proxy is rather stealthy and you need to know if something gets
placed in the cache regardless of the reason. The ofs callouts don't
completely capture that. So, I guess we are back to having a callout from
FileCache. But we will also need a callout when a file gets deleted
because you will need to deregister the file.
Now, speaking of registering and deregistering. I would strongly recommend
the registration and deregistration happen from a separate process. The
callout should simply write the action needed to a file queue and another
program reads the queue and does what is needed. I say this because Rucio
is essentially the LFC with a different face and its performance
characteristics are likely the same. Knowing that the LFC was not
particularly speedy I doubt Rucio will be any faster when it comes to
registering and deregistering files, especially when dozens of sites
start doing it. Plus, it's likely to suffer occasional failures and you
don't want the file cache to grind to a halt just because of a Rucio
hicup.
Andy
On Tue, 9 Dec 2014, Doug Benjamin wrote:
> Hi Andy,
>
> Please be more specific when the ofs layer should be called and when it
> should
> not be called. I do not understand the statement "open r/o with file
> placement"
> What information doe sthe OFS layer actually send to the script?
>
> Thanks,
>
> Doug
>
> On 12/09/2014 02:39 AM, Andrew Hanushevsky wrote:
>> Hi Alja,
>>
>> Yes, there are other events. However, I think you should just remove all
>> he callouts from your caching proxy and tell Doug to use the event
>> notfication in the OFS layer. See,
>>
>> http://xrootd.org/doc/dev4/ofs_config.htm#_Toc392685004
>>
>> This is what this whole thing was meant for. I don't think you need to do
>> anything special in the caching layer except, perhaps, a call out for a
>> stage-in (i.e. open r/o with file placement which the ofs callout issn't
>> quite suitable).
>>
>> Andy
>>
>> On Mon, 8 Dec 2014, Alja Mrak-Tadel wrote:
>>
>> > @abh3
>> > I guess I misunderstood Doug's request. I thought he wants to have a
>> given command invoked only on file open event.
>> >
>> > Is there other events too? Like Mkdir, Remdir, and Rename.
>> >
>> >
>> > ---
>> > Reply to this email directly or view it on GitHub:
>> > https://github.com/xrootd/xrootd/pull/180#issuecomment-66158178
>>
>>
>> Reply to this email directly or view it on GitHub
>> <https://github.com/xrootd/xrootd/pull/180#issuecomment-66250104>.
>>
>>
>>
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