Linux IO Current affairs Detection Tool Iostat

Linux IO Current affairs Detection Tool Iostat

The Iostat command detects the load condition of the Linux system IO device, and running Iostat displays statistics from the last time the command was run. Users can obtain the required statistics by specifying the number and time of the statistics.

Iostat-d-K 1 10

The parameter-D indicates that the device (disk) usage status is displayed; k Some columns that use block are forced to use kilobytes, 1 indicates that the data is refreshed every 1 seconds, and 10 indicates a total of 10 times. As shown below:

Linux 3.13.0-52-generic (hello1-system-product-name) 05/16/2015 _i686_ (2 CPU)

Device:tps kb_read/s kb_wrtn/s Kb_read Kb_wrtn
SDA 1.16 26.53 13.85 4168324 2176045

Device:tps kb_read/s kb_wrtn/s Kb_read Kb_wrtn
SDA 0.00 0.00 0.00 0 0

Device:tps kb_read/s kb_wrtn/s Kb_read Kb_wrtn
SDA 0.00 0.00 0.00 0 0

Device:tps kb_read/s kb_wrtn/s Kb_read Kb_wrtn
SDA 0.00 0.00 0.00 0 0

Device:tps kb_read/s kb_wrtn/s Kb_read Kb_wrtn
SDA 0.00 0.00 0.00 0 0

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: The total amount of data read;

KB_WRTN: The total amount of data written, these units are kilobytes.

iostat-d-k-x 1 3

device:rrqm/s wrqm/s r/s w/s rkb/s wkb/s avgrq-sz avgqu-sz await r_await w_await SVCTM%util

SDA 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

The content becomes richer after the command line joins the x parameter:

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 is being merge per second.

RSEC/S: Number of sectors read per second;

wsec/: Number of sectors written per second.

Rkb/s:the number of read requests that were issued to the device per second;

Wkb/s:the number of write requests that were issued to the device per second;

The size of the AVGRQ-SZ average request sector Avgqu-sz is the length of the average request queue. There is no doubt that the shorter the queue, the better.

Await: The average time (in milliseconds) 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. This time includes the queue time and service time, that is, in general, await is greater than SVCTM, their difference is smaller, the shorter the queue time, conversely, the greater the difference, the longer the queue time, indicating that the system has a problem

SVCTM represents the average service time (in milliseconds) for each device I/O operation. If the value of SVCTM is close to await, indicating that there is little I/O waiting, disk performance is good, and if the value of await is much higher than the value of SVCTM, the I/O queue waits too long for the applications running on the system to become slower.

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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Linux IO Current affairs Detection Tool Iostat