iostat

Purpose

Displays I/O statistics for Oracle ASM disks in mounted disk groups.

Syntax and Description

iostat [--suppressheader] [-et] [--io] [--region] 
        [-G diskgroup] [interval]

iostat lists disk group statistics using the V$ASM_DISK_IOSTAT view.

Table 10-45 lists the syntax options for the iostat command.

Table 10-45 Options for the iostat command

Option	Description
`-e`	Displays error statistics (Read_Err, Write_Err).
`-G` `diskgroup`	Displays statistics for the disk group name.
`--suppressheader`	Suppresses column headings.
`--io`	Displays information in number of I/Os, instead of bytes.
`-t`	Displays time statistics (Read_Time, Write_Time).
`--region`	Displays information for cold and hot disk regions (Cold_Reads, Cold_Writes, Hot_Reads, Hot_Writes).
`interval`	Refreshes the statistics display based on the interval value (seconds). Use CTRL+C to stop the interval display.

Table 10-46 shows the statistics for a disk group. To view the complete set of statistics for a disk group, use the V$ASM_DISK_IOSTAT view.

Table 10-46 Attribute descriptions for iostat command output

Attribute Name	Description
Group_Name	Name of the disk group.
Dsk_Name	Name of the disk.
Reads	Number of bytes read from the disk. If the `--io` option is entered, then the value is displayed as number of I/Os.
Writes	Number of bytes written to the disk. If the `--io` option is entered, then the value is displayed as number of I/Os.
Cold_Reads	Number of bytes read from the cold disk region. If the `--io` option is entered, then the value is displayed as number of I/Os.
Cold_Writes	Number of bytes written from the cold disk region. If the `--io` option is entered, then the value is displayed as number of I/Os.
Hot_Reads	Number of bytes read from the hot disk region. If the `--io` option is entered, then the value is displayed as number of I/Os.
Hot_Writes	Number of bytes written to the hot disk region. If the `--io` option is entered, then the value is displayed as number of I/Os.
Read_Err	Number of failed I/O read requests for the disk.
Write_Err	Number of failed I/O write requests for the disk.
Read_Time	I/O time (in seconds) for read requests for the disk if the `TIMED_STATISTICS` initialization parameter is set to `TRUE` (0 if set to `FALSE`).
Write_Time	I/O time (in seconds) for write requests for the disk if the `TIMED_STATISTICS` initialization parameter is set to `TRUE` (0 if set to `FALSE`).

If a refresh interval is not specified, the number displayed represents the total number of bytes or I/Os. If a refresh interval is specified, then the value displayed (bytes or I/Os) is the difference between the previous and current values, not the total value.

Example

The following are examples of the iostat command. The first example displays disk I/O statistics for the data disk group in total number of bytes. The second example displays disk I/O statistics for the data disk group in total number of I/O operations.

Example 10-56 Using the ASMCMD iostat command

ASMCMD [+] > iostat -G data
Group_Name  Dsk_Name   Reads       Writes     
DATA        DATA_0000  180488192   473707520  
DATA        DATA_0001  1089585152  469538816  
DATA        DATA_0002  191648256   489570304  
DATA        DATA_0003  175724032   424845824  
DATA        DATA_0004  183421952   781429248  
DATA        DATA_0005  1102540800  855269888  
DATA        DATA_0006  171290624   447662592  
DATA        DATA_0007  172281856   361337344  
DATA        DATA_0008  173225472   390840320  
DATA        DATA_0009  288497152   838680576  
DATA        DATA_0010  196657152   375764480  
DATA        DATA_0011  436420096   356003840  

ASMCMD [+] > iostat --io -G data
Group_Name  Dsk_Name   Reads  Writes  
DATA        DATA_0000  2801   34918   
DATA        DATA_0001  58301  35700   
DATA        DATA_0002  3320   36345   
DATA        DATA_0003  2816   10629   
DATA        DATA_0004  2883   34850   
DATA        DATA_0005  59306  38097   
DATA        DATA_0006  2151   10129   
DATA        DATA_0007  2686   10376   
DATA        DATA_0008  2105   8955    
DATA        DATA_0009  9121   36713   
DATA        DATA_0010  3557   8596    
DATA        DATA_0011  17458  9269