1. Storage information and the Site Status Board
Andrea Sciabà
MTF meeting 6/10/201

2. Outline SSB storage view Collected information Issues and ambiguities
Conclusions

3. SSB storage view
The goal is to collect storage-related site information in a table
The SSB provides historical plots
Can use colour codes to highlight anomalous values
A previous version existed but it was not maintained and was never used
Useful links:

4. New storage view layout

5. PhEDEx information Custodial: amount of custodial data at the site
Non-custodial: amount of non-custodial data at the site
Incoming: amount of subscribed data not at the site
Total subscribed or resident?
By group?
Caveat: proliferation of columns

6. Pledges Taken from SiteDB Will add those from REBUS Question:
Yellow: > 1 quarter old
Red: > 1 year old
Will add those from REBUS
Question:
Which ones are to be trusted more?

7. BDII information
These GLUE attributes are used and so defined by WLCG:
TotalOnlineSize: the total online space available at a given moment
UsedOnlineSize: the space occupied by available and accessible files that are not candidates for garbage collection
FreeOnlineSize: Total – Used
InstalledOnlineCapacity: used for accounting purposes, the size of the physical space of a SE
Same for Nearline

8. BDII issues and ambiguities
Information clearly wrong for all T1 sites apart from ASGC
What to report if a SE creates more replicas of some files?

9. Two conflicting interpretations
“Site” interpretation
Used is the space occupied by files
Free is the space not occupied by files
“User” interpretation
Used is the amount of data stored
Free is the amount of data that could be added
We need both! Naively, one could:
Ask for the BDII to provide the “site” info
Use the PhEDEx agent to calculate the “user” info
Although the “free” space could be tricky: maybe add the “overhëad” as a site-specific parameter?

10. Pragmatic approach
For the time being, try to make the best possible use of the BDII information
Fix the obvious issues (e.g. RAL declares 2.2 Exabytes of used tape)
Maybe in 90% of cases the numbers are usable for accounting and operations…
Or, ask at least the T1’s to provide their storage usage numbers in a standard format
And stop asking them to update the weekly twiki
Publish the numbers in the SSB

11. Conclusions
The SSB historical plots could be used to generate storage accounting plots
The SSB is not convenient for too fine-grained information
E.g. disk usage by group
Three main sources of information:
Pledges: REBUS or SiteDB?
PhEDEx agent and namespace dumps for space usage (from CMS point of view)
Site information for physical space usage (either from BDII or from custom sources)