iostat

IO. sh # iostat is used to view disk activity statistics # display the load of all devices r/s: The number of read I/O devices completed per second. That is, rio/s; w/s: the number of write I/O devices completed per second. That is, iostat such as wio/s # refresh the disk IO information every 2 seconds, in addition, iostat is displayed three times at a time.

First, check the hard disk read speedCommand: Hdparm-t/dev/sda5Printed: Timing buffered disk reads:254 MB in 3.01 seconds = 84.34 mb/secDescription: Be able to specify which hard disk to query for!Second, find the most consumption of iowait processOperation Steps:1./etc/init.d/syslog Stop2. Echo 1 >/proc/sys/vm/block_dump3. DMESG | Egrep "read| Write|dirtied "| Egrep-o ' ([a-za-z]*) ' | Sort | uniq-c | Sort-rn | HeadDon't forget to turn off Block_dump and start the syslog when you're done.4. ech

line 4th: +buffers/cache, that is, there is too little memory for the application, and it is time to consider optimizing the program or adding memory.IostatYou can use the Iostat tool to view the number of process IO requests, the time it takes for the system to process IO requests, and then to analyze whether there are bottlenecks in IO aspects of the process and operating system interactions.The following example is used with the

Linux Performance Tuning Command essenceTime: 2010-6-23First, see the hard drive read speedCommand: Hdparm-t/dev/sda5Printed: Timing buffered disk reads:254 MB in 3.01 seconds = 84.34 mb/secDescription: Can specify which hard disk to query the OH.Ii. finding the most iowait-consuming processOperation Steps:1./etc/init.d/syslog Stop2. Echo 1 >/proc/sys/vm/block_dump3. DMESG | Egrep "read| Write|dirtied "| Egrep-o ' ([a-za-z]*) ' | Sort | uniq-c | Sort-rn | HeadDon't forget to turn off Block_dump

. Another reason is to verify the high IO wait. Use iostat-x 1 to display the I/O status of the physical storage device in use: [username @ server ~] $ Iostat-x 1 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm % util cciss/c0d0 0.08 5.94 1.28 2.75 17.34 69.52 21.60 0.11 4.12 1.66 cciss/c0d0p1 0.00 0.00 0.00 0.00 0.00 0.00 5.30 0.00 8.76 5.98 0.00 cciss/c0d0p2 0.00 0.00 0.00 0.00 0

io.sh# #iostat是查看磁盘活动统计情况 # #显示全部设备负载情况 r/s: Number of Read I/O devices completed per second. That is, rio/s;w/s: The number of write I/O devices completed per second. That is, wio/s and other Iostat # #每隔2秒刷新磁盘IO信息, and 3 times per display Iostat 2 3# show the IO information of a disk iostat-d sda1# #显示tty和cpu信息

can see the percentage of CPU wasted on I/O wait; the higher the number, the more CPU resources are waiting for I/O permissions WA--iowaitAmount of the CPU has been waiting for I/O to complete.Finding which disk is being written to Find that disk is being written The above top command shows I/O wait from the system as a whole but it does don't tell you what disk is being affected; For this we'll use the Iostatcommand. The top command above describes an I/O wait as a whole, but it does not i

information is displayed only once when the output is periodically cycled. L Delay: Represents the time interval between two outputs. L Count: The number of times that the interval is specified according to "delay". The default is 1. For example: Vmstat 3 Indicates that the output information is updated every 3 seconds, the output is cycled, and CTRL + C stops the output. Vmstat 3 5 Indicates that the output information is updated every 3 seconds, and the output is stopped after 5 times.

only once when the output is periodically cycled. L Delay: Represents the time interval between two outputs. L Count: The number of times that the interval is specified according to "delay". The default is 1. For example: Vmstat 3 Indicates that the output information is updated every 3 seconds, the output is cycled, and CTRL + C stops the output. Vmstat 3 5 Indicates that the output information is updated every 3 seconds, and the output is stopped after 5 times. 2.

The statistical relationship between await util in the disk partition lvm, lvmawait Recent projects need to monitor the I/O loads of machines. When talking about I/O loads, the first two indicators are await util.Util: percentage of the time that the device processes IO requests in the past period of time.Await: The queuing time of a request in IOscheduler plus the processing time of the physical device (an IO request starts to be calculated when it is submitted from the general block device lay

io.sh# #iostat是查看磁盘活动统计情况 # #显示所有设备负载情况 r/s: Number of Read I/O devices completed per second. That is, rio/s;w/s: The number of write I/O devices completed per second. That is, wio/s and other Iostat # #每隔2秒刷新磁盘IO信息, and 3 times per display Iostat 2 3# shows the IO information of a disk iostat-d sda1# #显示tty和cpu信息

of the problem so easily, but you will eventually feel the impact on your application. Only an adequate understanding of the application will guide you in determining the root cause of the problem. For example, in front of this series, we discussed the importance of ensuring that the heap is not paged. The maximum heap size specified with the-XMX switch should be less than the total amount of physical memory installed on the system (shown by "Bootinfo–r" or "Lsattr-el sys0-a Realmem" For more s

/used是系统可用/占用的内存；对应用程序来说-/+ buffers/cache是可用/占用内存,因为buffers/cache很快就会被使用。We should look at the application from the perspective of our work.1.3 Hard Drive View 1, view hard disk and partition information:fdisk -l2. Check the disk space usage of the file system:df -h3. Check the I/O performance of the hard disk (show once every second, show 5 times):iostat -x 1 5The Iostat is included in the package Systat a

is located in the/etc/munin/plugins directory. You can see that the files in the/etc/munin/plugins directory point to the files in the/usr/share/munin/plugins directory. Therefore, iostat and iostat_ios not supported by telnet can be solved in this way. # cd /etc/munin/plugins/# ln -s /usr/share/munin/plugins/iostat iostat# ln -s /usr/share/munin/plugins/iostat_

impact on the system load, primarily because one or more cores may be blocked by disk IO or network IO, and these core tasks (i.e. processes) can be carried out only after the completion of disk IO or network IO. These processes use PS aux to view all in the "D" state, which is the non-disruptive sleep state.The discovery process is one thing to wait for IO to finish, and the reason for verifying high io Wait is another matter. Use "Iostat–x 1" to di

First, view with the top command top–16:15:05 up 6 days, 6:25, 2 users, load average:1.45, 1.77, 2.14tasks:147 Total, 1 running, 146 sleeping, 0 stopped, 0 zombieCpu (s): 0.2% us, 0.2% sy, 0.0% ni, 86.9% ID, 12.6% wa, 0.0% Hi, 0.0% simem:4037872k Total, 4003648k used, 34224k free, 5512k buffersswap:7164948k Total, 629192k used, 6535756k free, 3511184k cached See 12.6% WA Percentage of CPU time spent on Io wait, high io pressure above 30% Second, with Ios