uuid:虚拟机的唯一标识，如08e89e41-d2c2-4c5d-ba2a-c0d180942270
column_family(metric): 'cpu','vmnetwork','mem_max','mem_free','nic_incoming','nic_outgoing','blk_read','blk_write'
super_column_family:当column_family为vmnetwork,cpu,mem*时为total，其他情况为'vnet0','vda'等
timestamp: 时间戳，如1357628942
option:额外选项，用来处理数据，'sum','max','min','avg','sam'
period:时间间隔
获得某一虚拟机一段时间内某一度量标准记录值
api-client -get <uuid> <column_family> <super_column_family> <timestamp_from> <timestamp_to>
api-client -get 08e89e41-d2c2-4c5d-ba2a-c0d180942270 cpu total 1357628942 1357629699
获得某一虚拟机一段时间内某一度量标准分析值
api-client -get <uuid> <column_family> <super_column_family> <option> <period> <timestring_from> <timestring_to>
api-client 08e89e41-d2c2-4c5d-ba2a-c0d180942270 cpu total sum 5 2013-01-08T02:09:02 2013-01-08T02:21:05
显示所有某一度量标准的所有内容
api-client -l <metric>
api-client -l cpu
时间格式转换
api-client -t <timestamp>
api-client -d <timestring>
api-client -t 1111111111
api-client -d 2013-01-09T10:10
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