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Performance Monitoring Guide

OceanStor Dorado V3 Series V300R002

This document describes performance monitoring of storage systems, including the monitoring method, indicator planning, configuration monitoring, and problem diagnosis.
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Analyzing the CPU Performance

Analyzing the CPU Performance

The CPU capability is the most critical factor that determines the maximum performance of a storage controller. Therefore, this is a priority area of analysis when locating a performance problem.

Checking the CPU Usage of Controllers

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. For example,

  • Write I/Os consume more CPU resources than read I/Os do.
  • Random I/Os consume more CPU resources than sequential I/Os do.
  • IOPS-sensitive services consume more CPU resources than bandwidth-sensitive services do.
  • iSCSI networks consume more CPU resources than Fibre Channel networks do.

To query the CPU usage of the current controller, use SystemReporter or run the CLI command.

  • Use SystemReporter.

    Operation path: Monitoring > Real-Time Monitoring > Controller

  • On the CLI, run show performance controller.
    admin:/>show performance controller controller_id=0A 
    0.Max. Bandwidth(MB/s)                      
    1.Queue Length 
    2.Bandwidth(MB/s) / Block Bandwidth(MB/s)     
    4.Read Bandwidth(MB/s)                        
    5.Average Read I/O Size(KB) 
    6.Read Throughput(IOPS)(IO/s)                 
    7.Write Bandwidth(MB/s) 
    8.Average Write I/O Size(KB)                  
    9.Write Throughput(IOPS)(IO/s) 
    10.Read I/O Granularity Distribution: [0K,1K)(%) 
    11.Read I/O Granularity Distribution: [1K,2K)(%) 
    12.Read I/O Granularity Distribution: [2K,4K)(%) 
    13.Read I/O Granularity Distribution: [4K,8K)(%) 
    14.Read I/O Granularity Distribution: [8K,16K)(%)  
    15.Read I/O Granularity Distribution: [16K,32K)(%) 
    16.Read I/O Granularity Distribution: [32K,64K)(%) 
    17.Read I/O Granularity Distribution: [64K,128K)(%) 
    18.Read I/O Granularity Distribution: [128K,256K)(%)           
    19.Read I/O Granularity Distribution: [256K,512K)(%) 
    20.Read I/O Granularity Distribution: >= 512K(%)               
    21.Write I/O Granularity Distribution: [0K,1K)(%) 
    22.Write I/O Granularity Distribution: [1K,2K)(%)              
    23.Write I/O Granularity Distribution: [2K,4K)(%) 
    24.Write I/O Granularity Distribution: [4K,8K)(%)              
    25.Write I/O Granularity Distribution: [8K,16K)(%) 
    26.Write I/O Granularity Distribution: [16K,32K)(%)            
    27.Write I/O Granularity Distribution: [32K,64K)(%) 
    28.Write I/O Granularity Distribution: [64K,128K)(%) 
    29.Write I/O Granularity Distribution: [128K,256K)(%) 
    30.Write I/O Granularity Distribution: [256K,512K)(%)  
    31.Write I/O Granularity Distribution: >= 512K(%) 
    32.CPU Usage(%)                                        
    33.Memory Usage(%) 
    34.Percentage of Cache Flushes to Write Requests(%)    
    35.Cache Flushing Bandwidth(MB/s) 
    36.Read Cache Hit Ratio(%)                             
    37.Write Cache Hit Ratio 
    38.Cache Read Usage(%)                                 
    39.Cache Write Usage(%) 
    40.Average IO Size(KB)                                 
    41.% Read 
    42.% Write                                             
    43.Max IOPS(IO/s) 
    44.Service Time(Excluding Queue Time)(us)            
    45.Average I/O Latency(us) 
    46.Max. I/O Latency(us)                                
    47.Average Read I/O Latency(us) 
    48.Average Write I/O Latency(us)                       
    49.Max. Read I/O Size(KB) 
    50.Max. Write I/O Size(KB)                             
    51.Max. I/O Size(KB) 
    52.The cumulative count of I/Os                        
    53.The cumulative count of data transferred in Kbytes 
    54.The cumulative elapsed I/O time(ms)                 
    55.The cumulative count of all reads 
    56.The cumulative count of all read cache hits(Reads from Cache) 
    57.The cumulative count of data read in Kbytes(1024bytes = 1KByte) 
    58.The cumulative count of all writes                                             
    59.The cumulative count of Write Cache Hits (Writes that went directly to Cache) 
    60.The cumulative count of data written in Kbytes                                 
    61.Cache page utilization(%) 
    62.Cache chunk utilization(%) 
    Input item(s) number seperated by comma:

If the CPU utility 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 utility 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/product/OMM/. 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.

Functions Related to the CPU Performance

By default, the underclocking function is enabled in a storage system. When the CPUs work under a light load or if the utility threshold is reached, the underclocking function may reduce the system performance.

To conserve energy the underclocking function is enabled to reduce power consumption during off-peak hours. When the CPU usage is low, the clock frequency is automatically reduced. Use the CLI to log in to the storage system and switch to the developer mode. To check the clock frequency in this mode, run show cpu.

admin:/>change user_mode current_mode user_mode=developer 
developer:/>show cpu 

  ID        Temperature(Celsius)  Voltage(V)  Work Frequency(MHz) 
  --------  --------------------  ----------  ------------------- 
  CTE0.A.0  51                    0.8         2100                  
  CTE0.A.1  52                    0.8         2100                
  CTE0.B.0  50                    0.8         2100                  
  CTE0.B.1  50                    0.8         2100                 
  Current Frequency(MHz)  Frequency Enable  
  ----------------------  ----------------  
  1200                    Yes               
  1200                    Yes               
  2101                    Yes               
  2101                    Yes 
  • Work Frequency (MHz) indicates the CPU clock frequency.
  • Current Frequency (MHz) indicates the current CPU clock frequency. If Current Frequency (MHz) is lower than Work Frequency (MHz), the CPU clock frequency is reduced.
  • Frequency Enable refers to the status of the CPU underclocking function. Yes indicates that this function has been enabled and No indicates it is disabled.

Performance levels vary when the CPU work at low and high clock frequency. For example, in a light-load test, tasks such as: running the dd command, copying a single file, and using IOmeter to test single concurrency, the performance level is relatively low. Therefore, before conducting such tests, it is recommended that you disable the underclocking function by running change cpu frequency in developer mode.

developer:/>change cpu frequency enabled=no 
DANGER: You are going to modify the frequency for CPU. This operation may interrupt services or cause service exceptions.  
Suggestion: Before you perform this operation, determine whether the modification is necessary. 
Have you read danger alert message carefully?(y/n)y 

Are you sure you really want to perform the operation?(y/n)y 
Command executed successfully.     
Updated: 2019-07-17

Document ID: EDOC1100049152

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