The sysstat package contains utilities to monitor system performance and usage activity. Sysstat contains various utilities, common to many commercial Unixes, and tools you can schedule via cron to collect and historize performance and activity data.
iostat reports CPU statistics and input/output statistics for devices, partitions and network filesystems.
mpstat reports individual or combined processor related statistics.
pidstat reports statistics for Linux tasks (processes) : I/O, CPU, memory, etc.
sar collects, reports and saves system activity information (CPU, memory, disks, interrupts, network interfaces, TTY, kernel tables,etc.)
sadc is the system activity data collector, used as a backend for sar.
sa1 collects and stores binary data in the system activity daily data file. It is a front end to sadc designed to be run from cron.
sa2 writes a summarized daily activity report. It is a front end to sar designed to be run from cron.
sadf displays data collected by sar in multiple formats (CSV, XML, etc.) This is useful to load performance data into a database, or import them in a spreadsheet to make graphs.
sysstat is just a manual page for sysstat configuration file, giving the meaning of environment variables used by sysstat commands.
nfsiostat-sysstat reports input/output statistics for network filesystems (NFS).
cifsiostat reports CIFS statistics.
The following “sar -b” command reports I/O statistics. “1 3″ indicates that the sar -b will be executed for every 1 second for a total of 3 times.
root@ansible:/root/.ssh# sar -b 1 3 Linux 3.8.0-19-generic (ansible) 03/24/2014 _x86_64_ (1 CPU) 12:20:15 AM tps rtps wtps bread/s bwrtn/s 12:20:16 AM 151.11 1.11 150.00 8.89 152177.78 12:20:17 AM 193.33 1.11 192.22 8.89 193511.11 12:20:18 AM 186.81 1.10 185.71 8.79 189758.24 Average: 177.12 1.11 176.01 8.86 178523.99
-b Report I/O and transfer rate statistics. The following values are displayed:
Total number of transfers per second that were issued to physical devices. A transfer is an I/O request to a physical
device. Multiple logical requests can be combined into a single I/O request to the device. A transfer is of indeter‐
Total number of read requests per second issued to physical devices.
Total number of write requests per second issued to physical devices.
Total amount of data read from the devices in blocks per second. Blocks are equivalent to sectors and therefore have
a size of 512 bytes.
Total amount of data written to devices in blocks per second.
iostat reports CPU, disk I/O, and NFS statistics. The following are some of iostat command examples.
Iostat without any argument displays information about the CPU usage, and I/O statistics about all the partitions on the system as shown below.
root@ansible:/root/.ssh# iostat Linux 3.8.0-19-generic (ansible) 03/24/2014 _x86_64_ (1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.20 0.01 0.47 0.18 0.00 99.14 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn sda 0.34 0.99 16.90 368219 6283388 root@ansible:/root/.ssh# iostat Linux 3.8.0-19-generic (ansible) 03/24/2014 _x86_64_ (1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.20 0.01 0.47 0.18 0.00 99.14 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn sda 0.34 0.99 16.90 368227 6283516
root@ansible:/root/.ssh# vmstat -d disk- ------------reads------------ ------------writes----------- -----IO------ total merged sectors ms total merged sectors ms cur sec ............................................................................................................ sda 19086 6087 738326 322356 108247 85791 14735736 6081592 0 712
FIELD DESCRIPTION FOR DISK MODE
total: Total reads completed successfully
merged: grouped reads (resulting in one I/O)
sectors: Sectors read successfully
ms: milliseconds spent reading
total: Total writes completed successfully
merged: grouped writes (resulting in one I/O)
sectors: Sectors written successfully
ms: milliseconds spent writing
cur: I/O in progress
s: seconds spent for I/O