linux-Common Commands-iostat&vmstat

1, hard disk read and write performance,

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-D: Show a specific hard disk, there is no hard drive path is the default all
-K: Displayed in kilobytes
1: Statistical interval of 1 seconds
10: Total Statistics 10 times
TPS: The number of transmissions per second of the device (indicate, transfers per second, were issued to the.). "One-time transfer" means "one-time I/O request". Multiple logical requests may be merged into "one I/O request". The size of the "one transfer" request is unknown.
KB_READ/S: The amount of data read from the device (drive expressed) per second, KB_WRTN/S: The amount of data written to the device (drive expressed) per second, Kb_read: Total amount of data read, KB_WRTN: Total amount of data written ; These units are kilobytes.
The initial value is large because the cumulative read and write volume is displayed.

2,iostat-x parameters, viewing device usage (%util), Response time (await)
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RRQM/S: How much of this device-dependent read request is merged per second (when the system call needs to read the data, the VFS sends the request to each FS, and if FS finds that different read requests read the same block data, FS merges the request into the merge); wrqm/ S: How much of this device-related write request per second has been merge.
R/S: Number of Read requests per second in response, w/s: Number of Write requests per second, rkb/s: Amount of data read per second, wkb/s: Amount of data written per second
Await: The average time (in microseconds) of processing per IO request. This can be understood as the response time of IO, generally the system IO response time should be less than 5ms, if greater than 10ms is relatively large.
%util: All processing io time, divided by total statistic time, in the statistical time. For example, if the statistic interval is 1 seconds, the device has 0.8 seconds to process Io, and 0.2 seconds is idle, then the device's%util = 0.8/1 = 80%, so this parameter implies the device's busy level. Generally, if this parameter is 100% indicates that the device is already running close to full load (of course if it is a multi-disk, even if%util is 100% because of the concurrency of the disk, disk usage may not be the bottleneck).

 
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Procs
R: Number of processes waiting in the run queue
B: Number of processes waiting on Io

Memory
SWPD: Virtual memory usage, unit: KB
Free: idle memory, in kilobytes
Buff: The amount of memory that is used as a cache, in kilobytes: KB

Swap
Si: Number of swap pages from disk swap to memory, in kb/seconds
So: number of swap pages from memory swap to disk, in kb/seconds

Io
BI: Number of blocks sent to block device, units: Blocks/sec
Bo: Number of blocks received from a block device, units: Blocks/sec

System
In: Number of interrupts per second, including clock interrupts
CS: The number of environment (context) switches per second

Cpu
Display as a percentage of total CPU usage
Us:cpu Use time
SY:CPU System Usage Time
ID: Idle Time
R, column B is typically 0, which means there is no wait process, and if not 0 indicates a problem with the system performance
Si, so two columns, indicating the frequency of memory exchange, if the value of a large number of long-term memory is not enough, to exchange data with the hard disk, you can also indicate that the data to read and write is different every time
Bi, bo two columns, which indicates that I/O input and output is very frequent

linux-Common Commands-iostat&vmstat