This is sysstat's Frequently Asked Questions!
Be sure to read this carefully before asking for help...

#################

Q> When I compile sysstat, it fails with the following message:
make: msgfmt: Command not found
make: ***[locales] Error 127

A> The msgfmt command belongs to the GNU gettext package.
If you don't have it on your system, just answer 'n' (for "no") at the
question
"Enable National Language Support (NLS)? [y]"
during config stage (make config), then compile sysstat as usual (make ;
make install).
Please read the README-nls file included in sysstat source package to learn
some more about National Language Support.

#################

Q> The sar command complains with the following message:
Invalid system activity file

A> The format of the daily data files created by the sar command you are
now using is not compatible with the format of the files created by a
previous version of sar.
The solution is easy: just log in as root and remove by hand the files
located in the /var/log/sa directory:
# rm /var/log/sa/sa??

#################

Q> The sar command complains with the following message:
Cannot append data to that file

A> The internal structure of the data file does not allow sar to append
data to it. The data file may come from another machine, or the components
of the current box, such as the number of processors, may have changed.
Use another data file, or delete current daily data file, and try again.

#################

Q> The sar command complains with the following message:
Invalid data format

A> This error message means that sadc (the system activity data collector that
sar is using) is not consistent with the sar command. In most cases this is
because the sar and sadc commands do not belong to the same release of the
sysstat package. Remember that sar searches for sadc in predefined
directories (/usr/lib/sa, /usr/local/lib/sa, ...) before looking in current
directory!

#################

Q> I get the following error message when I try to run sar:

$ sar
Cannot open /var/log/sa/sa30: No such file or directory

A> Please read sar(1) manual page! Daily data files are created in the
/var/log/sa directory using the data collector (sadc) or using option
-o with sar. Once they are created, sar can display statistics saved
in those files.
But sar can also display statistics collected "on the fly": just enter
the proper option on the command line to indicate which statistics are
to be displayed, and also specify an <interval> and <count> number.
Eg:
# sar 2 5  --> will report CPU utilization for each two seconds five
times.
# sar -n DEV 3 0  --> will report network device utilization for each
3 seconds, in an infinite loop.

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Q> Is sar daily data files fully compatible with Sun Solaris format of
sar files?

A> No, the format of the binary data files created by sysstat's sar command
is not compatible with formats from other Unixes, because it contains
data which are closely linked to Linux.
For the same reason, sysstat cannot work on other platforms than Linux...

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Q> I have some troubles running sar on my SMP box. My server crashes
with a kernel oops:
Feb 17 04:05:00 bolums1 kernel: Unable to handle kernel paging request
at virtual address fffffc1c
Feb 17 04:05:00 bolums1 kernel: current->tss.cr3 = 19293000, %cr3 = 19293000
Feb 17 04:05:00 bolums1 kernel: *pde = 0026b067
Feb 17 04:05:00 bolums1 kernel: *pte = 00000000
Feb 17 04:05:00 bolums1 kernel: Oops: 0000
Feb 17 04:05:00 bolums1 kernel: CPU:    0
Feb 17 04:05:00 bolums1 kernel: EIP:
<...>

A> The trouble you have is triggered by a *Linux* kernel bug, not a sysstat
one... The best solution is to upgrade your kernel to the latest stable
release.
Also, if you cannot upgrade your box, try to compile sysstat after
answering 'y' to the question:
"Linux SMP race in serial driver workaround?"
at config stage (make config). Indeed, we found that 2.2.x kernels
(with x <= 15) have an SMP race condition, that the sar command
may trigger when it reads the /proc/tty/driver/serial file.

#################

Q> The "Average:" results from the sar command are just rubbishes...
Eg.:
 11:10:00 AM       all      0.54      0.00      0.89     98.57
 11:20:01 AM       all      3.02      8.05     22.85     66.08
 11:30:01 AM       all      8.15      0.00      2.31     89.54
 11:40:01 AM       all      8.03      0.00      2.42     89.55
 11:50:01 AM       all     16.04      0.00      2.81     81.16
 12:00:00 PM       all     21.11      0.00      3.23     75.66
 03:40:01 PM       all    100.01    100.01    100.01      0.00
 04:40:00 PM       all    100.00      0.00    100.00      0.00
 04:50:00 PM       all      5.87      0.00      1.26     92.87
 05:00:00 PM       all      4.70      0.00      1.48     93.82
 05:10:00 PM       all      4.93      0.00      1.29     93.78
 Average:          all    100.22    100.20    100.13      0.00

A> Your sar command was not installed properly (in fact, you compiled it but
forgot to run 'make install' as the last stage). Whenever your computer
is restarted (as it is the case here between 12:00:00 PM and 03:40:01 PM),
the sysstat shell script must be called by the system, so that the
LINUX RESTART message can be inserted into the daily data file, indicating
that the relevant kernel counters have been reinitialized...

#################

Q> My database (e.g. MySQL) doesn't appear to understand the time zone
displayed by 'sar -H'...

A> The format includes the timezone detail in the output. This is to make
sure it is communicated clearly that UTC is how the data is always
converted and printed. Moreover we don't depend on the TZ environment
variable and we don't have some data converted to a different timezone
for any reason, known or unknown.
When you deal with accounting data, when you have raw data you always 
want it in UTC.  Of course, you want it to all be the same when loading 
into a database. If your database has no way to deal with timezones,
then write a short script to strip the "UTC" characters to load into the
database.

#################

Q> When I try to compile sysstat, it fails and says it cannot find some
include files:
In file included from /usr/include/bits/errno.h:25,
                 from /usr/include/errno.h:36,
                 from common.c:26:
/usr/include/linux/errno.h:4: asm/errno.h: No such file or directory
<SNIP>
common.c: In function `get_kb_shift':
common.c:180: `PAGE_SIZE' undeclared (first use in this function)
common.c:178: warning: `size' might be used uninitialized in this function
make: *** [common.o] Error 1

A> Make sure that you have the Linux kernel sources installed in
/usr/src/linux. Also make sure that the symbolic link exists in the
/usr/src/linux/include directory and points to the right architecture, e.g.:
# ll /usr/src/linux/include/asm
lrwxrwxrwx   1 root     root            8 May  5 18:31 /usr/src/linux/include/asm -> asm-i386

#################

Q> I cannot see all my disks when I use the iostat command...

A> Yes. This is a kernel limit. At the present time Linux doesn't maintain
statistics for every devices. Old kernels (2.2.x for instance) used to
maintain stats for the first four devices. The accounting code has changed
in 2.4 kernels, and the result may (or may not) be better for your system.

#################

Q> iostat -x doesn't report disk I/O statistics...

A> From sysstat's README file: The iostat command has been updated to take
advantage of Stephen Tweedie's kernel patch to display extended I/O statistics
(option '-x' for iostat).
You can find Stephen's patch here:
ftp://ftp.uk.linux.org/pub/linux/sct/fs/profiling
Stephen used to maintain his patch for various kernel versions, but it is
no longer the case. You will have to get one of the relevant patches (if they
are still there and update it by hand to suit your kernel.
Note that some distros have this patch already applied.

#################

Q> I don't understand the output of iostat. It doesn't match what I expect it
to be...

A> By default iostat displays I/O activity in blocks per second. With old
kernels (i.e. older than 2.4.x) a block is of indeterminate size and therefore
the displayed values are not useful.
With recent kernels (kernels 2.4 and later), iostat is now able to get disk
activities from the kernel expressed in a number of sectors. If you take a
look at the kernel code, the sector size is actually allowed to vary although
I have never seen anything other than 512 bytes.

--	
Sebastien Godard <sebastien.godard@wanadoo.fr> is the author and the current
maintainer of this package.

