lustre add README

lustre/README.md

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+Lustre Client Ganglia Metrics
+
+These python scripts collect lustre filesystem metric for ganglia-gmond module.
+
+The scripts attempt to collect separate metrics for each lustre
+filesystem mounted on the client. In addition to typical read/write bandwidth
+metrics, the scripts also attempt to collect inode-related metrics (network RPC calls from the client to the object storage servers).
+
+Lustre client exposes metrics through linux sysfs
+(ie. /proc/fs/lustre/...).  
+
+The "llite" metrics are high-level aggergate metrics of the underlying
+storage targets. On older versions of lustre, there are known bugs in
+the llite values. The "osc" metrics are lower level, offering values
+for each storage target (ie. LUN) that is accessed by the client. Note
+that lustre client uses local (client-side) file caching which can
+affect these values.