Storage/SpaceTokens
Contents
Use of space tokens
The aim of this page is to give the GridPP storage group's guidance on the use of space tokens - particularly for non-LHC VOs.
- What is a spacetoken and why***
We start with what the LHC VOs are doing for some background.
Non LHC VOs
Small data requirements
- Use SE for temporary storage of job output
- No need for spacetokens ( though some SEs provide them by default).
Medium/large data requirements
- In addition to job output store experimental/simulation data at Tier-2 sites
- significant (>1TB) stored at Tier-2s.
- Space tokens recommended for all SE types to ensure space available for this data
- VOs recommended to ask for this from the beginning - to avoid problems with moving data into a space token.
LHC VOs
Atlas
Makes extensive use of spacetokens. Has been slowly consolidating them over time - their experience has been that having as few spacetokens as you need to represent different security permissions or use cases as possible is best.
CMS
CMS use space however it is made available - whether in spacetokens or not. Where they have been assigned spacetokens, it is almost always a single token as a reservation.
LHCb
Starting to use Tier-2 sites - where spacetokens will be used.
Alice
Don't use spacetokens
SEs
DPM, StoRM and dCache storage elements are all used at GridPP sites. Spacetokens are implemented in different ways for each of these storage elements.
DPM
Spacetoken and path orthogonal (though the storage group would recommend that VOs do keep them orthogonal).
Most sites provide storage not in a spacetoken for use by multiple VOs - this is suitable for staging job output.
Cleanup responsibility of VOs. Nothing to prevent one VO filling the space.
dCache
Spacetoken and path not orthogonal - by default space is configured in a spacetoken.
StoRM
Spacetoken and path not orthogonal - by default space is configured in a spacetoken.
