Storage information in the Site Status Board

This page explains the information published in the SSB via a specialized view called 'storage'.

First of all, a Data Service query returning all PhEDEx nodes is used to:

• find all nodes in a site
• the SE for each node

Second, the BDII is queried, and for all Storage Areas supporting CMS in a given PhEDEx site we sum up the following attributes:

• GlueSATotalOnlineSize
• GlueSAFreeOnlineSize
• GlueSAUsedOnlineSize
• GlueSATotalNearlineSize
• GlueSAFreeNearlineSize
• GlueSAUsedNearlineSize
• InstalledOnlineCapacity
• InstalledNearlineCapacity

The used space should measure the amount of storage capacity in use, while the free space is defined as the total capacity minus the used capacity. The total space is the same as the installed capacity only if all disk servers are up.

Third, for each site with PhEDEx nodes, we use queries like

https://cmsweb.cern.ch/phedex/datasvc/xml/prod/nodeusage?node=$node

to extract these parameters:

• cust_node_bytes
• cust_dest_bytes
• noncust_dest_bytes
• noncust_node_bytes

and define

incoming      = cust_dest_bytes + noncust_dest_bytes - cust_node_bytes - noncust_node_bytes
custodial     = cust_node_bytes
non_custodial = noncust_node_bytes

The following table summarizes all columns in the SSB and describes when a value is marked red (meaning an error condition)

-- AndreaSciaba - 04-Oct-2011