Last modified 12 years ago Last modified on 05/20/09 17:53:49

dCache Developers meeting Wednesday May, 20, 2009

Participants : Gerd, Paul, Timur, Dmitry, Vladimir


  • Performance degradation in dCache 1.9.2,
  • Release of branches,
  • Owen's bug,
  • Progress on counters interface.

Performance degradation

Preventative measures: count number of NFS msgs; number of PnfsManager msgs and check for regressions in Hudson.

Additional message when writing dcap and open: the client is sending a stat, then an open.

Timur: For getStorageInfo the number of msgs sent to the door is the same but different; in 1.9.0-5, two messages are sent, both fail. In 1.9.2-4, two msgs are sent, one fails and one succeeds.

Number of requests NFS requests depends

with one we have 1,100 getAttr, with the other is 970 getAttr.

How is the request to PnfsManager converted into NamespaceDriver? in PNFS

Timur to do some more investigation; we're think about it. The messages that PnfsManager receives; a different number of these msgs are failing.

Paul has a graph.


Timur: degrading of performance: reads took more than 170%.

Functionality; Tigran sent around a patch to disable writing space-token information.

Release as a top priority.

Step '09 2nd & 3rd week of June: 2nd week of June, both ATLAS and CMS run concurrently.

1 million per day (~10 Hz)

Owen's bug

# 4522; Bug reported by Flavia on behalf of Remi.

Dmitry to look into this.

# 4526; Question about space reservations.

Dmitry to look into this, too.

Counters interface

Paul to re-review Timur's code so it can be committed. Paul to submit the new interface for review asap. The plan is to migrate to the existing code to the new interfaces once they are committed.


Next meeting.