08-05-2010
"also I need to understand the "pseudo-swap" i found this statement in book but don't understand "if we have 1 giga memory and 1 giga swap we can run 1.75 g processes "
ok if we don't have the pseudo-swap how much processe in this situation 1 G ? i am asking "
When a process is created, swap is checked too see if there is enough swap space for that process. The swap space is not actually allocated at that moment.
So, if you have 1 GB of RAM and 1 GB of swap space and you want to start a 1,5 GB process on a system that does not have pseudo-swap activated, you will not be able to start that process.
If you have pseudo-swap active, meaning 1 GB of swap space and [up to] 75% of 1 GB RAM results in 1,75 GB "virtual" swap space, you will be able to start that 1.5 GB process.
In HP-UX 11 v1 and v2 pseudo-swap is controlled by this kernel parameter: swapmem_on (1 is on). In 11.3, pseudo-swap is always enabled and swapmem_on parameter is no longer present.
hope it's more clear now the pseudo-swap space concept.
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LEARN ABOUT OPENSOLARIS
sa1
sar(1M) System Administration Commands sar(1M)
NAME
sar, sa1, sa2, sadc - system activity report package
SYNOPSIS
/usr/lib/sa/sadc [t n] [ofile]
/usr/lib/sa/sa1 [t n]
/usr/lib/sa/sa2 [-aAbcdgkmpqruvwy] [-e time] [-f filename]
[-i sec] [-s time]
DESCRIPTION
System activity data can be accessed at the special request of a user (see sar(1)) and automatically, on a routine basis, as described
here. The operating system contains several counters that are incremented as various system actions occur. These include counters for CPU
utilization, buffer usage, disk and tape I/O activity, TTY device activity, switching and system-call activity, file-access, queue activ-
ity, inter-process communications, and paging. For more general system statistics, use iostat(1M), sar(1), or vmstat(1M).
sadc and two shell procedures, sa1 and sa2, are used to sample, save, and process this data.
sadc, the data collector, samples system data n times, with an interval of t seconds between samples, and writes in binary format to ofile
or to standard output. The sampling interval t should be greater than 5 seconds; otherwise, the activity of sadc itself may affect the sam-
ple. If t and n are omitted, a special record is written. This facility can be used at system boot time, when booting to a multi-user
state, to mark the time at which the counters restart from zero. For example, when accounting is enabled, the svc:/system/sar:default ser-
vice writes the restart mark to the daily data file using the command entry:
su sys -c "/usr/lib/sa/sadc /var/adm/sa/sa'date +%d'"
The shell script sa1, a variant of sadc, is used to collect and store data in the binary file /var/adm/sa/sadd, where dd is the current
day. The arguments t and n cause records to be written n times at an interval of t seconds, or once if omitted. The following entries in
/var/spool/cron/crontabs/sys will produce records every 20 minutes during working hours and hourly otherwise:
0 * * * 0-6 /usr/lib/sa/sa1
20,40 8-17 * * 1-5 /usr/lib/sa/sa1
See crontab(1) for details.
The shell script sa2, a variant of sar, writes a daily report in the file /var/adm/sa/sardd. See the OPTIONS section in sar(1) for an
explanation of the various options. The following entry in /var/spool/cron/crontabs/sys will report important activities hourly during the
working day:
5 18 * * 1-5 /usr/lib/sa/sa2 -s 8:00 -e 18:01 -i 1200 -A
FILES
/tmp/sa.adrfl
address file
/var/adm/sa/sadd
Daily data file
/var/adm/sa/sardd
Daily report file
/var/spool/cron/crontabs/sys
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWaccu |
+-----------------------------+-----------------------------+
SEE ALSO
crontab(1), sag(1), sar(1), svcs(1), timex(1), iostat(1M), svcadm(1M), vmstat(1M), attributes(5), smf(5)
NOTES
The sar service is managed by the service management facility, smf(5), under the service identifier:
svc:/system/sar
Administrative actions on this service, such as enabling, disabling, or requesting restart, can be performed using svcadm(1M). The ser-
vice's status can be queried using the svcs(1) command.
SunOS 5.11 20 Aug 2004 sar(1M)