When the CPU usage is high, the latency of system scheduling increases. As a result, the I/O latency increases.
The CPU usage of a storage system is closely related to and varies with I/O models and networking modes. To query the CPU usage of the current controller, use DeviceManager or run the CLI command.
l Use DeviceManager.
Navigation path: Insight > Performance > Analysis. Select Avg. CPU Usage (%) when creating a metric chart for a controller. After the metric chart is created, you can view it. For details about how to create a metric chart, see 3.5 Creating a Metric Chart.
l On the CLI, run show performance controller.
admin:/>show performance controller controller_id=0A
0.Memory Usage(%)
1.Percentage of Cache Flushes to Write Requests(%)
2.Cache Flushing Bandwidth(MB/s)
3.Read Cache Hit Ratio(%)
4.Write Cache Hit Ratio(%)
5.Cache Read Usage(%)
6.Cache Write Usage(%)
7.% Hit
8.Cache Water(%)
9.Cache page utilization(%)
10.Cache chunk utilization(%)
11.Max. Bandwidth(MB/s)
12.Queue Length
13.Bandwidth(MB/s) / Block Bandwidth(MB/s)
14.Throughput(IOPS)(IO/s)
15.Read Bandwidth(MB/s)
16.Average Read I/O Size(KB)
17.Read Throughput(IOPS)(IO/s)
18.Write Bandwidth(MB/s)
19.Average Write I/O Size(KB)
20.Write Throughput(IOPS)(IO/s)
21.Service Time(Excluding Queue Time)(us)
22.Read I/O Granularity Distribution: [0K,4K)(%)
23.Read I/O Granularity Distribution: [4K,8K)(%)
24.Read I/O Granularity Distribution: [8K,16K)(%)
25.Read I/O Granularity Distribution: [16K,32K)(%)
26.Read I/O Granularity Distribution: [32K,64K)(%)
27.Read I/O Granularity Distribution: [64K,128K)(%)
28.Read I/O Granularity Distribution: >= 128K(%)
29.Write I/O Granularity Distribution: [0K,4K)(%)
30.Write I/O Granularity Distribution: [4K,8K)(%)
31.Write I/O Granularity Distribution: [8K,16K)(%)
32.Write I/O Granularity Distribution: [16K,32K)(%)
33.Write I/O Granularity Distribution: [32K,64K)(%)
34.Write I/O Granularity Distribution: [64K,128K)(%)
35.Write I/O Granularity Distribution: >= 128K(%)
36.Average IO Size(KB)
37.% Read
38.% Write
39.Max IOPS(IO/s)
40.Max. I/O Size(KB)
41.Max. Read I/O Size(KB)
42.Max. Write I/O Size(KB)
43.The cumulative count of I/Os
44.The cumulative count of data transferred in Kbytes
45.The cumulative elapsed I/O time(ms)
46.The cumulative count of all reads
47.The cumulative count of data read in Kbytes(1024bytes = 1KByte)
48.The cumulative count of all writes
49.The cumulative count of data written in Kbytes
50.Max. I/O Latency(us)
51.Average I/O Latency(us)
52.Average Read I/O Latency(us)
53.Average Write I/O Latency(us)
54.CPU Usage(%)
55.SCSI IOPS (IO/s)
56.ISCSI IOPS (IO/s)
57.NFS operation count per second
58.CIFS operation count per second
59.Total Disk IOPS(IO/s)
60.READ Disk IOPS(IO/s)
61.WRITE Disk IOPS(IO/s)
62.Disk Max. Usage(%)
63.NFS connection count
64.CIFS session count
65.Unmap Command Bandwidth (MB/s)
66.Unmap Command IOPS (IO/s)
67.Avg. Unmap Command Size (KB)
68.Avg. Unmap Command Response Time (us)
69.WRITE SAME Command Bandwidth (MB/s)
70.WRITE SAME Command IOPS (IO/s)
71.Avg. WRITE SAME Command Size (KB)
72.Avg. WRITE SAME Command Response Time (us)
73.Full Copy Read Request Bandwidth (MB/s)
74.Full Copy Read Request IOPS (IO/s)
75.Avg. Full Copy Read Request Size (KB)
76.Avg. Full Copy Read Request Response Time (us)
77.Full Copy Write Request Bandwidth (MB/s)
78.Full Copy Write Request IOPS (IO/s)
79.Avg. Full Copy Write Request Size (KB)
80.Avg. Full Copy Write Request Response Time (us)
81.ODX Read Request Bandwidth (MB/s)
82.ODX Read Request IOPS (IO/s)
83.Avg. ODX Read Request Size (KB)
84.Avg. ODX Read Request Response Time (us)
85.ODX Write Request Bandwidth (MB/s)
86.ODX Write Request IOPS (IO/s)
87.Avg. ODX Write Request Size (KB)
88.Avg. ODX Write Request Response Time (us)
89.ODX Write Zero Request Bandwidth (MB/s)
90.ODX Write Zero Request IOPS (IO/s)
91.Avg. ODX Write Zero Request Size (KB)
92.Avg. ODX Write Zero Request Response Time (us)
93.AI Cache Hit Ratio(%)
Input item(s) number separated by comma:54
CPU Usage(%) : 15
If the CPU usage remains high for a prolonged amount of time, the controller's performance will reach a maximum. In this event, it is recommended that you migrate some services to another storage system to mitigate the service pressure.
You can set the CPU usage threshold of a storage system. The default value is 90%. Once the threshold is exceeded, the system will start to collect information and saves it to /OSM/coffer_data/omm/perf/exception_info/. The size of all files in this directory should not exceed 14 MB. Otherwise, existing files are overwritten. The information collected is used for subsequent performance tuning or problem locating and analysis.
