I'm using opscenter 5.1.3 with cassandra 2.1.7 in Ubuntu 14.04 with lvm disks.
Opscenter shows all information except disk utilization and storage capacity and keeps saying that it has trouble connection to the agents (but data for other stats keeps working normally). I have reinstalled the agents with opscenter option.
In /var/log/datastax-agent/agent.log I see:
ERROR [os-metrics-4] 2015-07-06 12:56:00,468 Short os-stats collector failed java.lang.NullPointerException
at clojure.lang.Numbers.ops(Numbers.java:942)
at clojure.lang.Numbers.lt(Numbers.java:219)
at clojure.lang.Numbers.min(Numbers.java:4007)
at opsagent.rollup$add_value.invoke(rollup.clj:156)
at opsagent.rollup$add_value.invoke(rollup.clj:156)
at opsagent.rollup$process_keypair$fn__1435.invoke(rollup.clj:235)
at psagent.cache$update_cache_value_default$fn__1163$fn__1164.invoke(cache.clj:25)
at clojure.lang.AFn.applyToHelper(AFn.java:161)
at clojure.lang.AFn.applyTo(AFn.java:151)
at clojure.lang.Ref.alter(Ref.java:174)
at clojure.core$alter.doInvoke(core.clj:2244)
at clojure.lang.RestFn.invoke(RestFn.java:425)
at opsagent.cache$update_cache_value_default$fn__1163.invoke(cache.clj:25)
at clojure.lang.AFn.call(AFn.java:18)
at clojure.lang.LockingTransaction.run(LockingTransaction.java:263)
at clojure.lang.LockingTransaction.runInTransaction(LockingTransaction.java:231)
at opsagent.cache$update_cache_value_default.invoke(cache.clj:24)
at opsagent.rollup$process_keypair.invoke(rollup.clj:235)
at opsagent.rollup$process_metric_map.invoke(rollup.clj:241)
at opsagent.os.collection$start_os_stat_collection$send_metric__15899.invoke(collection.clj:80)
at opsagent.os.linux_metrics$sendmap.invoke(linux_metrics.clj:12)
at opsagent.os.linux_metrics$report_mem_stats.invoke(linux_metrics.clj:134)
at opsagent.os.linux_metrics$collectors$wrap_short_collector__9128$fn__9129.invoke(linux_metrics.clj:270)
at opsagent.os.collection$start_pool$fn__15870.invoke(collection.clj:39)
at clojure.lang.AFn.run(AFn.java:24)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:304)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)