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This page has news, information, documentation and links software for the sysstat utilities that I created for Linux. The sysstat utilities are a collection of performance monitoring tools for Linux. These include sar, sadf, mpstat, iostat, pidstat and sa tools. Go to the Features page to display a list of sysstat's features, or see the Documentation page to learn some more about them.
Sysstat is Open Source / Free Software, and is freely available under the GNU General Public License, version 2.

Old news

Sunday September 20th, 2009

Sysstat 9.0.5 released (stable version).
With this version, sysstat can now pretty-print device names whose minor numbers are greater than or equal to 256. This should prove useful especially on large Linux clusters.

Sunday July 19th, 2009

Sysstat 9.0.4 released (stable version).
This version fixes a nasty memory corruption bug in sadc. Huge thanks to Jonathan Kamens for pinpointing it. Apart from that, other changes here are really small stuff.

Sunday May 24th, 2009

Sysstat 9.0.3 released (stable version).
Various trivial changes or small improvements have been added here. They concern iostat, mpstat, sar, sadf, you name it. See the full changelog available from the download page to know all the details.

Thursday April 2nd, 2009

Sysstat 9.0.2 released (stable version).
More bug fixes and improvements in this version: A memory corruption has been fixed in iostat and pidstat, where a segfault could happen when a list of comma-separated values following option -p was entered on the command line. With regard to improvements, sadc can now collect partition statistics in addition to disk ones. Go on testing, as I want sysstat 9.0.x to become rock solid...!

Sunday March 7th, 2009

Sysstat 9.0.1 released (stable version).
Yep... This is my brown-paper-bag release, as this one mainly fixes a crash with the sar command, where a pointer was freed twice. Please upgrade!

Sunday March 1st, 2009

Sysstat 9.0.0 released (stable version).
OK. I said that there would be another development version (8.1.9). I lied. Well, I had in mind to add several metrics related to power management (CPU temperature, fan speed, etc.) It turned out to be more difficult than what I had imagined (yes, I need help for this... Any volunteer out there?) As a consequence, only CPU frequency statistics have been added to sar here. Anyway here is 9.0.0, the first version of a new, long-awaited, stable series!

Sunday January 11th, 2009

Sysstat 8.1.8 released (development version).
This version adds support for IPv6-related protocols (IPv6, TCPv6, ICMPv6, UDPv6) and a bunch of new metrics for sar. Sysstat 8.1.8 also includes various fixes and improvements for iostat. See the full changelog available from the download page. Note that there should be a last development version (8.1.9) before switching to the stable series (9.0.x). Enjoy!

Thursday November 13th, 2008

Sysstat 8.1.7 released (development version).
A major feature has been added to sar in this version: sar has now support for SNMPv2 statistics. Lots of new metrics have been added so that the user can now monitor IP, TCP, ICMP and UDP network traffic. Other changes in this version include the addition of option -l to pidstat to display the whole command line for each task.

Tuesday September 30th, 2008

Sysstat 8.1.6 released (development version).
This version includes improvements and bug fixes mainly for pidstat and mpstat commands. I hope then to begin adding SNMP statistics to sar in next sysstat version. So the development series will go on for a while.

Monday July 14th, 2008

Sysstat 8.1.5 released (development version).
New interesting features have been added in this version. First, sysstat and its commands sar, mpstat and pidstat have now support for virtual machine time accounting: They can display the time spent by the CPU to run a virtual processor or the time spent by a process in the virtual machine. New metrics have also been added to sar: In particular the amount of memory needed for current workload is now collected. This can prove useful to track possible OOM conditions.

Sunday June 22nd, 2008

Sysstat 8.1.4 released (development version).
This version includes a bunch of patches that I had put in my fridge for the past few months. I have also added back a feature that I had removed from sar in previous sysstat version. This feature (number of interrupts per processor) is now available with mpstat and its option "-I CPU".

Sunday May 25th, 2008

Sysstat 8.1.3 released (development version).
Here is the long awaited second technical release of sysstat. Although it doesn't add new features, the sar, sadc and sadf commands have been largely rewritten in a non-monolithic way with a generic design architecture. It will now be much simpler to add new system metrics (the so-called "activities") to get a wider insight into your Linux system. Expected results are performance analysis and tuning made easier for system administrators.

Sunday March 16th, 2008

Sysstat 8.1.2 released (development version).
OK. This version should have been the second (and last) technical release, but in fact, it's not. There is really too much work left to do, and completing it should still take one or two months(*). So I made 8.1.2 available, which includes new features mainly for iostat and sadf commands.
(*) For those of you who are wondering what kind of changes this next technical release is about, let's say that it will be a major rewriting of sar and sadc...

Sunday February 10th, 2008

Sysstat 8.1.1 released (development version).
Sysstat 8.1.1 should be considered mainly as a technical release: Data files created by sar have now additional information in their header (sysstat version used to create them, machine architecture...), error messages have been improved and made more explicit, source code have been reworked (large functions split into smaller ones, comments added,...). See the changelog for all the details. Note that next sysstat version will also be a technical release, and you will probably have to wait for version 8.1.3 planned for April to see (plenty of) new features being merged again.

Sunday January 6th, 2008

Sysstat 8.0.4 released (stable version).
This version adds minor feature enhancements. It also includes a new XML Schema that can be used to check the XML output generated by "sadf -x". This version of sysstat is intended to be the last one of the stable 8.0 series. The next development series will start soon and I have a bunch of exciting new features that I plan to add in the coming months...

Sunday November 18th, 2007

Sysstat 8.0.3 released (stable version).
You will find still more bug fixes in this version: First, the pidstat command made sometimes a confusion between PID and TID, resulting in erroneous statistics values being displayed. This version also fixes a problem with hotplug CPU support which made sar and mpstat parse /proc/interrupts sometimes incorrectly when some CPUs were set offline. Give this version a good try to see if there are any pending problems because I would like this stable series to become really rock solid...

Friday October 26th, 2007

Sysstat 8.0.2 released (stable version).
This version of sysstat adds a new option to pidstat (-w) enabling you to display per task switching activity (number of voluntary and involuntary context switches per second), providing that you have a recent Linux kernel (2.6.23+). Also some annoying bugs have been fixed here: a memory leak in pidstat which made its option -t display only headers after a few iterations, and a problem with device names displayed by sar.

Sunday September 30th, 2007

Sysstat 8.0.1 released (stable version).
In this version the pidstat command has been greatly improved with the addition of a new option that enables it to display statistics for every thread managed by the system. Also "pidstat -T CHILD" works now a bit differently: It reports global statistics for the selected tasks and all their children (and not statistics for the children only).

Sunday September 2nd, 2007

Sysstat 8.0.0 released (stable version).
This version is a stable one, which means that sar's data files format should no longer change for a while. Sysstat 8.0.0 includes several important changes: First, the pidstat command (which appeared in sysstat version 7.1.4) is now able to display CPU and page fault statistics for the child processes of a task. Then, some statistics that were previously gathered by sar from kernel tables (sar -v) have been removed since they had been made obsolete in 2.6 kernels. On the other hand sar now collects new stats like the number of pseudo-terminals in use (sar -v) or the number of sockets in TIME_WAIT state (sar -n SOCK). Last, this version of sysstat also fixes a security flaw in its startup script (CVE-2007-3852). Read the release notes available from the download page to know all the bug fixes and improvements included in this version.

Sunday July 8th, 2007

Sysstat 7.1.6 released (development version).
New metrics have been added to sar in this version. They concern virtual memory and should be useful for all of you wanting to get a more detailed insight into Linux memory management. This version also includes the usual set of bugfixes. Enjoy!

Saturday June 9th, 2007

Sysstat 7.1.5 released (development version).
At last, this version includes a long awaited feature: per-process I/O statistics, that you can now display with the pidstat command and its new option -d. Of course, you will need a recent Linux kernel for that (2.6.20+). Also with this sysstat version, it is now possible to insert a timestamped comment in the binary data file created by sar/sadc. This may be helpful to automate some performance tests...

Sunday April 29th, 2007

Sysstat 7.1.4 released (development version).
This version of sysstat adds a new command (pidstat) aimed at reporting statistics for Linux tasks (processes). This command will replace sar's options -x and -X and will have many more features (e.g. I plan to add per-process I/O statistics in next sysstat release).
Another change in this version which is worth being noted is the addition of option -N to iostat. This option enables the user to query any device-mapper devices for their registered device name. It should prove useful for viewing LVM2 statistics.

Tuesday March 27th, 2007

Sysstat 7.1.3 released (development version).
In this release you will find numerous bug fixes and improvements. Changes concern hotplug CPU support, support for keeping sar logfiles for more than one month, configuration script, isag, you name it. So please give it a good testing and tell me if anything goes wrong.

Sunday March 4th, 2007

Sysstat 7.1.2 released (development version).
OK. Here is yet another version of sysstat which includes various small improvements. Among others, sysstat now has better hotplug CPU support: It no longer assumes that CPU#0 can never be disabled. Also sar datafiles format has changed to become a little more compact.

Wednesday February 21st, 2007

Sysstat 7.1.1 released (development version).
The development cycle starts again with this version.  This one includes support for autoconf (thanks to Ivana Varekova from RedHat for that). Configuring sysstat is now done with the well known "./configure" script. But for those of you who might miss the old interactive configuration process, I have added "iconfig", a front-end to "configure" which enables you to set parameters values interactively.

Sunday February 4th, 2007

Sysstat 7.0.4 released (stable version).
This one should be the last version of the stable 7.0 series. With this version, the user will be able to keep sar data for more than one month (thanks to John Caruso for the original idea). This version also fixes a compilation problem on GNU/kFreeBSD.

Sunday December 3rd, 2006

Sysstat 7.0.3 released (stable version).
With this version, iostat is now able to display I/O statistics for network filesystems (NFS). This is a major improvement for iostat but which will require a recent kernel to work (2.6.17 or later).

Sunday October 22nd, 2006

Sysstat 7.0.2 released (stable version).
This version mainly includes a new important feature: support for hotplug CPU's. Sar and mpstat are now able to detect disabled processors and to display their data when they are set online.

Sunday September 17th, 2006

Sysstat 7.0.1 released (stable version).
Some more small improvements and bug fixes in this new version. For example I changed the way sadf considered the time entered on the command line with -s and -e options, so that sadf output is now always consistent with that of sar. See the changelog available from the download page to know the other changes.

Sunday July 9th, 2006

Sysstat 7.0.0 released (stable version).
OK. This is the beginning of a new stable series again for sysstat. I hope to make it last a bit so that sysstat may have the time to become rock solid. In this version sar takes into account a new environment variable that tells sar to use UTC to save its data and determine its current daily data file. This should prove useful for servers with users located across several timezones. Also this version now uses sysconf() system call to get the number of ticks per second, which should be the right way to do it...

Thursday June 1st, 2006

My Internet provider changed its name from Wanadoo to Orange. My mail address remains unchanged for the moment, but this web site is now at Please update your bookmarks!

Thursday May 24th, 2006

Sysstat 6.1.3 released (development version).
Several minor features and bug fixes were added in this version. Please read the changelog available from the download page for more details.

Sunday April 23rd, 2006

Sysstat 6.1.2 released (development version).
An important bug has been fixed in this version. Users wanting to get NFS statistics with sar are strongly encouraged to upgrade. Process statistics monitoring has also been improved with this version : sar is now able to display stats for processes that are launched during the execution of sar when option -x ALL or -X ALL is used.

Saturday April 8th, 2006

Sysstat web site has been completely redesigned! You can now find more documentation, sysstat Frequently Asked Questions (FAQ), and even a short online tutorial... Enjoy!

Wednesday February 22nd, 2006

Sysstat 6.1.1 released (development version).
Previous sysstat version appeared quite stable, so I decided to start a new development series. This version only adds CPU "steal" time to the stats displayed by sar -u, as I had promised to do.

Monday November 28th, 2005

Sysstat 6.0.2 released (stable version).
This version fixes a bug that was corrupting device names displayed by iostat on 64-bit architectures. It also adds a new field to mpstat and iostat to display CPU "steal" time (which is at the present time only used on s390 architectures!) Sar will also display this field when a new sysstat developmentr begins (6.1.x).

Saturday June 25th, 2005

Sysstat 6.0.1 released (stable version).
Several bugs have been fixed in this version, among them a memory leak and one that prevented sar -b from working. Also note that from now on, sar always displays the stats onto the screen even if a filename has been entered on the command line with option -o.

Saturday May 14th, 2005

Sysstat 6.0.0 released (stable version).
At last, a new sysstat stable release is available again. I have been really busy for the past few months, that's why sysstat development has slowed a bit. Anyway version 6.0.0 is here for you now, with new statistics gathered by sar and several bugs fixed. Oh, and I have named it 6.0.0 and not 5.2.0 for the format of sar logfiles is not compatible with that of sysstat 5.0.x...!

Friday February 25th, 2005

Sysstat 5.1.5 released (development version).
A new output format is now available to display sar data: using -x option with sadf enables you to create an XML document containing the statistics. The source package includes the corresponding DTD. This version also fixes a few bugs, one of them concerning some of the disks statistics as displayed by sar -d. Note that this version should be the last one of the development series (next release will be sysstat 5.2.0).

Sunday January 2nd, 2005

Sysstat 5.1.4 released (development version).
New stats have been added to sar : it can now collect and display NFS data of a client or server box. Also a few bugs have been fixed in this release: See changelog for details.

Monday November 22nd, 2004

Sysstat 5.1.3 released (development version).
Important things have been added here in this release: first, sar -d have been greatly improved with the addition of new fields displaying more disk activities. Moreover sar -d is now able to display device names as they appear in /dev thanks to a configuration file (sysstat.ioconf). Also sar -b is now working whatever the kernel version used, even with recent ones.

Friday November 5th , 2004

Sysstat 5.1.2 released (development version).
Numerous small changes in this version. More important is the /proc/partitions support which has been added to sar to get disk activity. Also note that beginning with sysstat 5.1.2 disk activity is no longer read by sadc by default: Option -d must be explictly set on the command line.

Saturday October 9th , 2004

Sysstat 5.1.1 released (development version).
That's it: A new development series starts with sysstat 5.1.1. Two important things here. First, sar reads several stat counters as 64-bit unsigned integers to follow 2.6 kernels changes. Also a new command named sadf has been added to sysstat. This command is aimed at displaying daily data files contents in various formats. At the present time, sadf only replaces sar -h and sar -H. Other possibilities will be added in future sysstat versions.

Monday August 9th , 2004

Sysstat 5.0.6 released (stable version).
OK. There is yet another stable version of sysstat, which fixes the value of a field displayed by sar -v that was wrongly calculated... See changelog for full details. Next version should (hopefully) be sysstat 5.1.1 which is planned for the end of october.

Tuesday June 8th , 2004

Sysstat 5.0.5 released (stable version).
Maybe the last stable version before the beginning of a new development series. This one fixes a bug in the binary RPM file, where symlinks to sysstat script were wrong in the /etc/rc.d directories. It also get rid of 'mojibakes' that sar and mpstat could have displayed with some locales (especially ja_JP).

Thursday May 20th , 2004

Sysstat 5.0.4 released (stable version).
Small but important fixes in this release : some of them concern the sysstat shell script called on system reboot. A bug introduced in version 5.0.1 prevented it from working properly (LINUX RESTART messages could no longer be added automatically to daily data files on system restart).

Wednesday April 7th , 2004

Sysstat 5.0.3 released (stable version).
Various fixes and improvements added in this version, among which the major one concerns the handling of 'unsigned long long' counters which are beginning to appear in the kernel (see kernel 2.6.5 for example). Also note that the isag tool has been upgraded and it should now really fix the small temporary file vulnerability. 

Wednesday March 10th , 2004

Sysstat 5.0.2 released (stable version).
OK, sysstat 5.0.2 is ready for download at last. A few bugs have been fixed in this version. But above all, iostat can look for its extended statistics in the /proc/partitions file again if available. /proc/partitions support had been removed in sysstat 4.1.3 in favor of sysfs included in 2.6 kernels. Its support has been added again here because many production servers are still using 2.2.x and 2.4.x kernels today.

Friday February 27th , 2004

Sysstat 5.0.2 will be released Wednesday, March 10th.
With this version, iostat will be able again to get its extended statistics from /proc/partitions on 2.2 and 2.4 kernels !

Monday February 2nd , 2004

Sysstat 5.0.1 released (stable version).
The main improvement in this version is the addition of option -L to sadc, enabling it to lock its output file to prevent multiple instances from writing to it at once. Beside this, do not hesitate to try this version with recent 2.6 kernels to make sure it is really stable.

Monday December 15th, 2003

Good news : From now on, you have access to the source packages of old sysstat versions. This may be useful for some people, for example those who are still running old kernels and want extended statistics information with iostat. See the download section.

Sunday November 9th, 2003

Sysstat 5.0.0 released (stable version).
Yes... You read it: the new sysstat version 5.0.0 is now available on your favorite web site ;-) It has new improvements again, and even the documentation has been enhanced. So, just try it and you will feel better! And if you find any bugs left, well, tell me...

Sunday September 28th, 2003

Sysstat 4.1.7 released (development version).
OK. Here is the first sysstat version which should be 100% compliant with 2.6 Linux kernels. This version uses /proc/diskstats in addition to sysfs to get statistics for devices. Also several new statistics were added to sar (page faults, swap cached, devices stats....) whereas other ones considered not really useful were removed.
I'm waiting now for your feedback so that sysstat 5.0.0 can be released soon. Enjoy...

Wednesday August 20th, 2003

Sysstat 4.1.6 released (development version).
This version contains another bunch of fixes and optimizations (iostat, sar, mpstat). See the changelog file for details. Oh, and option -F was added to sadc to force the creation of its daily data file. This is particularly useful to avoid the  Invalid system activity file  error messages you get when the format of those files changes.
PS: I hope that next sysstat release (4.1.7), planned for october, will be fully kernel 2.6 compliant. My goal is to start again with a stable series (5.0.x) before the end of the year.

Tuesday July 22nd, 2003

Sysstat 4.1.5 released (development version).
Several important fixes are included in this release : sar -x / -X now work again (a buglet in sysstat 4.1.4 made these options unavailable). Also a bug, introduced in the 4.1.x series, made some LINUX RESTART messages to not be displayed by sar ; this is fixed here. Last, sar -P now works properly on machines with more than 32 processors.

Monday June 30th, 2003

Sysstat 4.1.4 released (development version).
Various minor bugfixes are included in this version, like the way sar handles overflow with interfaces counters. Option  -x SUM  was removed from sar, since the calculation of the total number of faults made by the system was rather tricky. Also the code was greatly cleaned, and sysstat should now be really lighter than before as a consequence. 

Thursday May 8th, 2003

Sysstat 4.1.3 released (development version).
OK. This is the first version of sysstat to take advantage of the sysfs filesystem, included in recent, cutting-edge Linux kernels. Thus iostat should now be fully compliant with 2.5/2.6 kernels. But as a consequence, iostat will no longer look for statistics in the /proc/partitions file. Those who need to display extended statistics with iostat while still using an older 2.4 kernel must use sysstat 4.1.2 (or sysstat 4.0.7). With regard to sar, it has not been updated to use sysfs : I would rather wait for 2.6 kernels to be available...

Thursday January 23rd, 2003

Sysstat 4.1.2 released (development version).
Lots of small and not so small changes in this release. Among others, sar -q now also displays load average for the past 15 minutes, and option -P has been added to sar to display stats on a per processor basis. Because of this, sar syntax has changed a little : sar -U ALL is replaced by sar -u -P ALL (or simply sar -P ALL), and sar -I PROC is replaced by sar -I SUM -P ALL.

Thursday January 2nd, 2003

Sysstat 4.1.1 released (development version).
This new year starts with a new development series for sysstat. The result will be a set of commands that will work with cutting edge Linux kernels (2.5.x and above). Sysstat 4.1.1 is the first version in this series. It includes I/O wait support by all the commands of sysstat.

Wednesday November 13th, 2002

Sysstat 4.0.7 released (stable version).
Small changes in this version : 1) the data for midnight time (00:00:00) is now saved in the daily data file before sar/sadc rotates it ; 2) mpstat -P can now be used even on UP machines.
NB: A new development series (4.1.x) is to begin soon to take into account newer 2.5/2.6 kernels.