Burke, S (Stephen) wrote:
> Testbed Support for GridPP member institutes
>>[mailto:[log in to unmask]] On Behalf Of Graeme A Stewart said:
>>At Glasgow we've decided to setup an new SRM SE (probably
>>DPM) and make our
>>old SE read only (the WNs will be told that the new SE is "close").
> One point there, the crucial thing is to make sure the "default SE"
> environment variable for all VOs points to the new one, as that's what
> gets used for writes. As far as the info system goes you should make
> *both* SEs "close" so jobs can find input files on both.
Thanks for the tip! I'm actually a bit confused as to the point of
CLOSE_SE for reading files - other than that reading will be assumed to
be reasonably fast because of the "close" property. If a job gets passed
a SURL of whatever type, sfn:// or srm:// then is must have to use
gridftp or srmGet to actually obtain the file for its use. I can see
that that gfal does define a gfal_seek function though I fail to see how
it could work in any sensible way (surely not using GridFTP's RESEND?).
I've heard tale of "CLOSE" meaning rfio or nfs access (reading the
recent thread on LCG-ROLLOUT), but in an SRM this would seem to make
little sense - you have to go through the SRM protocol to convert the
SURL into a TURL.
So shouldn't a job be able to read _any_ file from an SE in this case?
Or is there some resource broker criteria being involved here, so a job
won't reach a site if its input files are not "close"?
>>Do any of the SRMv1 clients support pinning? DPM has a
>>default pin time on
>>volatile storage, but the expts really have to be able to
> I would still say that this is irrelevant as long as no client software
> (middleware or experiment software) takes any notice of whether an SE is
> volatile or not!
I'm currently trawling through the experiment's latest TDR's to try and
find out what the idea is here. This will become a real issue as a DPM
volatile storage area will start its garbage collector to delete the
oldest unpinned files once the usage goes over some defined threshold.
Dr Graeme Stewart http://www.physics.gla.ac.uk/~graeme/
GridPP DM Wiki http://www.physics.gla.ac.uk/gridpp/datamanagement/