SRM conf call

7/6/2005

Olof, Sebastian, Peter : CERN

Arie, Alex : LBNL

Jon, Leo : FNAL

Shaun: RAL

LCG-SRM : v.1.1 + explicit pinning + space reservation

We need a complete feature, not a subset or part of a feature to implement

If we have v3 to agree by Sep, is it too late for LCG?

LCG SC4 by Jan 2006

As a working group, we�re not coordinating well with them, or they are not with us.

LCG has dCache (Timur), CASTOR (Olof), and DPM (Jean-Phillip) to work with. If these people agree on V3, LCG will consider.�

Why explicit pinning, vs. prepareToGet or prepareToPut

We need a use-case to see.� These are coming from the use case of tier1-tier2 copying. Needed in the staging area of storage. If telling them how to do, it should be okay.

Lifetime issue on space and file

Issue: e.g. space has 5 hours of lifetime. By the time the files arrive, the space lifetime may expire.

Another one (by Jon): files come into disk. Experiment wants to use the explicit pinning to keep the file in disk (long term pinning).�

If there is lifetime negotiation, it should be okay.

Q (by Jon): do we want all users to do that?

It�s the VO who decides. This is some policy issue that SRM wants to be out of: who has what by how much, user priority, etc.

How to enforce is another question.

By VO with analogy to patient with prescription to pharmacy.

VO gives proxy saying he�s admin. We�ll need some callout for VO policy.

We want to stay out of making decisions. May call out to VO for asking decisions.

This can be a bigger issue for the sep meeting. It�ll be nice to have requirements. Let�s look at some use cases. Let�s put a boundary to how far SRMs can go.

Summary:

Semantics of space and file lifetime: need to be clarified

Need use cases

Try and engage for LCG to work within v3 framework (dCache, DPM, Castor) and stay on the same page

Issue of remote get in SRM (discussion with Miron)

One SRM does not know anything about what�s going on in another SRM. It�s just waiting until file is ready.

This could be some kind of scheduling issue. Advertising local resources based on local environment, so that external scheduler can make decisions based on those.

We need some SRM communication for resource status, in addition to dynamic resource advertising.

Olof:

1. issue of list of file sizes for hints to reserve spaces for files: progressing

2. SC4 requirements for pinning
how to queue pinning? E.g. several users pinning the same file?
do we have history of pinning?
Arie: v2 has the same approach as v.1.1 basically. One way to do is to keep every pinning by every users. Another way is to have one ping for all users, and ignore all releases. It�s not good, so we (LBNL implementation) decided to have to keep all pins for all users.

3. LS issue: a lot of entries to return
do we maintain consistent snapshot? Or ?
client is supposed to handle duplicate entries of the same file when there are changes in the directory?
Arie: this is not really specified. All we have is offset and count.
Timestamp for getting newer files than the time stamp would be good and would work. And sort by the creation time or last modified time.

4. prepareToGet with file streaming: need publicity
file streaming without user�s release?
It has been there from the beginning. SRM wouldn�t know if the file is consumed without user release.

F2F meeting 9/14-15 at JLab.

Will find out logistics