Monitoring with the Sysstat tool collection
Ins and Outs
If you have kernel 2.6.20 or newer, with the CONFIG_TASK_IO_ACCOUNTING option built in, you can also use pidstat to monitor the I/O load for individual processes or whole groups. On a system with the right support, typing
pidstat -d 2 3
will generate output as shown in Figure 3. Pidstat will list the processes generating I/O and even tell you the type (read or write), along with the data throughput (in Kbps).
To allow this to happen, you need a recent kernel, the packages from the Sysstat website, and a matching cron configuration.
Listing 1 shows the /etc/cron.d/sysstat file on Ubuntu. In the simplest of all cases, the following two lines in /etc/crontab are all you need:
*/10 * * * * root /usr/lib/sa/sa1 1 1 53 23 * * * root /usr/lib/sa/sa2 -A
The first entry starts sadc (the System Activity Data Collector), the server daemon that collects data every second and stores its findings under /var/log/sa. The logfile format is saXX, where XX is the date. The second part with sar -A just rotates the logfiles.
Listing 1
Cronjobs for Sysstat
Iostat and Mpstat
Besides sar and pidstat, the Sysstat package also includes iostat and mpstat. Mpstat monitors the processor you pass in to it; iostat is popular with file, database, and mail server administrators as a tool for measuring system I/O load by drive, disk, partition, and filesystem.
For example,
iostat -m -n 10 2
monitors an NFS mount point and outputs the volume of data in megabytes (Listing 2). For a single partition, you can do the same by typing iostat -m -x sda2 10 2, as shown in Listing 3.
Listing 2
NFS Mount Point Activity
Listing 3
I/O for a Partition
Absolutely Essential
The latest version of the Sysstat package includes some new features that many administrators have been waiting for – above all, the ability to monitor I/O load per process. Linux had some catching up to do in this regard. It is a pity you can't use this feature on older servers or on enterprise distributions. It is questionable whether distributions will respond with matching kernels and packages in future releases.
If you can do without detailed I/O statistics, a combination of sar and kSar will give you a flexible and comprehensive interface that lets you monitor multiple servers at the same time.
Even if you don't have a full-fledged monitoring system, you will still be able to identify recurring bottlenecks and take steps to fix any performance issues before a system crash.
Infos
« Previous 1 2
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
TUXEDO Computers Unveils Linux Laptop Featuring AMD Ryzen CPU
This latest release is the first laptop to include the new CPU from Ryzen and Linux preinstalled.
-
XZ Gets the All-Clear
The back door xz vulnerability has been officially reverted for Fedora 40 and versions 38 and 39 were never affected.
-
Canonical Collaborates with Qualcomm on New Venture
This new joint effort is geared toward bringing Ubuntu and Ubuntu Core to Qualcomm-powered devices.
-
Kodi 21.0 Open-Source Entertainment Hub Released
After a year of development, the award-winning Kodi cross-platform, media center software is now available with many new additions and improvements.
-
Linux Usage Increases in Two Key Areas
If market share is your thing, you'll be happy to know that Linux is on the rise in two areas that, if they keep climbing, could have serious meaning for Linux's future.
-
Vulnerability Discovered in xz Libraries
An urgent alert for Fedora 40 has been posted and users should pay attention.
-
Canonical Bumps LTS Support to 12 years
If you're worried that your Ubuntu LTS release won't be supported long enough to last, Canonical has a surprise for you in the form of 12 years of security coverage.
-
Fedora 40 Beta Released Soon
With the official release of Fedora 40 coming in April, it's almost time to download the beta and see what's new.
-
New Pentesting Distribution to Compete with Kali Linux
SnoopGod is now available for your testing needs
-
Juno Computers Launches Another Linux Laptop
If you're looking for a powerhouse laptop that runs Ubuntu, the Juno Computers Neptune 17 v6 should be on your radar.