04-08-2013
Quote:
Originally Posted by
butchie3980
the idea is to trigger swap usage, and we try to monitor that two ways, using top and "swap -l"
first step that we try is to fill up /tmp with a couple of simple "mkfile 10g /tmp/memeater01" style commands. We can see the available ram decrease each time we create one of those files in /tmp.
we get down to about 10-ish GB of free ram and start to encounter "no space available" errors when trying to create tmp files.
You have exhausted your virtual memory, which includes most of the RAM plus all of the swap area when you get these messages. Can you post the actual numbers and the commands you use to measure memory and swap usage ?
Quote:
Next think we tried was to push it over the edge using a program that simply uses malloc() calls to reserve ram and hold onto it. we can also watch the avalable ram decrease until the 10GB (roughly) threshold and then this program dies.
How (why) does it die ?
Quote:
A combination of both /tmp files and the malloc() program still dies around the 10gb free threshold and we never ever see any indicators that swap space is being used.
Are you you actually accessing all of the the allocated pages ?
Quote:
Just downloaded VTS, and started reading the documentation. Tried a test run, but don't know if the defaults are what we need. We only enabled the memory test and ran it. According to top, free RAM dropped to 36GB and stayed there, Free swap stayed the same no changes. We sat there and watched top for about 30 minutes before getting pulled away to a meeting. so we stopped it and decided to try later. are there some parameters we need to set or change?
VTS is to stress test you hardware in order to detect faulty components. I don't think this is what you are looking for, although I don't precisely understand what exactly you are trying to achieve/fix ...
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LEARN ABOUT CENTOS
shell-quote
SHELL-QUOTE(1) User Contributed Perl Documentation SHELL-QUOTE(1)
NAME
shell-quote - quote arguments for safe use, unmodified in a shell command
SYNOPSIS
shell-quote [switch]... arg...
DESCRIPTION
shell-quote lets you pass arbitrary strings through the shell so that they won't be changed by the shell. This lets you process commands
or files with embedded white space or shell globbing characters safely. Here are a few examples.
EXAMPLES
ssh preserving args
When running a remote command with ssh, ssh doesn't preserve the separate arguments it receives. It just joins them with spaces and
passes them to "$SHELL -c". This doesn't work as intended:
ssh host touch 'hi there' # fails
It creates 2 files, hi and there. Instead, do this:
cmd=`shell-quote touch 'hi there'`
ssh host "$cmd"
This gives you just 1 file, hi there.
process find output
It's not ordinarily possible to process an arbitrary list of files output by find with a shell script. Anything you put in $IFS to
split up the output could legitimately be in a file's name. Here's how you can do it using shell-quote:
eval set -- `find -type f -print0 | xargs -0 shell-quote --`
debug shell scripts
shell-quote is better than echo for debugging shell scripts.
debug() {
[ -z "$debug" ] || shell-quote "debug:" "$@"
}
With echo you can't tell the difference between "debug 'foo bar'" and "debug foo bar", but with shell-quote you can.
save a command for later
shell-quote can be used to build up a shell command to run later. Say you want the user to be able to give you switches for a command
you're going to run. If you don't want the switches to be re-evaluated by the shell (which is usually a good idea, else there are
things the user can't pass through), you can do something like this:
user_switches=
while [ $# != 0 ]
do
case x$1 in
x--pass-through)
[ $# -gt 1 ] || die "need an argument for $1"
user_switches="$user_switches "`shell-quote -- "$2"`
shift;;
# process other switches
esac
shift
done
# later
eval "shell-quote some-command $user_switches my args"
OPTIONS
--debug
Turn debugging on.
--help
Show the usage message and die.
--version
Show the version number and exit.
AVAILABILITY
The code is licensed under the GNU GPL. Check http://www.argon.org/~roderick/ or CPAN for updated versions.
AUTHOR
Roderick Schertler <roderick@argon.org>
perl v5.16.3 2010-06-11 SHELL-QUOTE(1)