US FAX Status Report

Wei Yang

2012-08-27

Site Status

• Most sites are online and stable• Observe successful failover between US and UK sites

– Via EU-BNL redirection bridge (mutual xrootd.redirect)• Observe sporadic crashing, debugging with OU• Suspect there is minor opr issue at AGLT2.• Observe large number of hosts joining FAX using

10.44.14.X– Need to enforce “cms.allow domain_name

• Need to update site configuration to send out redirection summary reports.

Need a new xrootd release• Xrootd failover redirection issue

– Failover mechanism causes target redirector to respond slowly for files that exist.

– Observed at SLAC Tier 2 xrootd storage• It happens after large number of failover (xrootd) redirection

– FAX redirectors could be effected• Xrootd failover redirection is widely used in FAX• Refers to redirect via “xrootd.redirect” (so it is not CMSd redirection)

• Xrootd monitoring– A bug prevents UPD packet from been sent out– Requests handled by sendfile() are not counted toward total bytes read.

• On linux, >8k reads use sendfile() --- almost all sequential reads use large blocks, including file transfer via xrdcp, gridftp, etc.