the Virtual Data Toolkit distributed by the Open Science Grid Richard Jones University of Connecticut CAT project meeting, June 24, 2008

2 the UConn Grendl cluster  62 dual-processor nodes  mix of old and newer cpu’s  7 TB of shared storage  condor job management  heavy reliance on nfs  home-built processing workflow package called “openShop”

CAT project meeting, June 24, the UConn Grendl cluster  Efficient MPI job scheduling using the condor “parallel universe”  Large datasets staged on large distributed “parallel virtual file system” (pvfs) volumes high throughput low cost – no dedicated file servers reduced cpu – data location coupling

CAT project meeting, June 24, Obstacles to scaling  nfs servers x clients = N 2 problem 1 server down hangs/drags all N clients starts to be a problem with 62 nodes cross-site nfs is an admin nightmare!  pvfs 1 server down hangs entire volume poor recovery, compared to nfs invasive installation procedure

CAT project meeting, June 24, CAT project scaling  data large base-input datasets  non-volatile  non-replicated relatively compact PWA event lists  volatile  replicated complex workflow pattern global management scheme is needed

CAT project meeting, June 24, CAT project scaling  processor co-scheduling cpu resource allocation in clusters  network latency  allocation persistence not tied to client location access independent of local userid global resource monitoring required