04-10-2010
Quote:
Originally Posted by
MarkSeger
I just answered a previous note about memory usage and pointed the user at collectl. There are a couple of things worth noting - collectl is VERY lightweight, on the order of using <0.1% of the cpu when sampling system data every 10 seconds! When trying to track down something tricky you ALWAYS need fine grained time or you never see those spikes that so ofter offer at the least expected time. In fact if you want to sample once a second you're still <1%.
But back to the problem at hand. While you can certainly run ps from cron every hours there are 2 reasons why you might not want to. First of all, sampling once an hour isn't really going to help much unless you get real lucky. Second, even if ps did tell you something you might also want to get other things that happened at the time in question like CPU, memory usage, open files, etc. but you don't have access to it because you didn't think to ask ahead of time.
With collectl, you just start it running as a daemon and it will collect more than you thought of to ask. It will even collect info on your slab usage and a runaway allocation of slab memory can certainly trigger the out-of-memory killer.
Just note that collectl only monitors slabs/processes once a minute because there are high load tasks...
-mark
Thanks Mark! collectl seems to be the type of monitor tool I need to use to keep track of events; certainly as you have pointed out a much better solution than cron and ps. I'll give it a go. Cheers!
Dave
10 More Discussions You Might Find Interesting
1. Shell Programming and Scripting
Hello,
I host a couple of Call of Duty gameing servers. There are some hackers who love the crash them. When they crash them it simply causes a segmentaion fault and kills the PID. I was wondering it you could help me write a script to simply restart the program after it has been crashed. The... (9 Replies)
Discussion started by: Phobos
9 Replies
2. Shell Programming and Scripting
how to find the chid process id from given parent process id.... (the chid process doesnot have sub processes inturn) (3 Replies)
Discussion started by: guhas
3 Replies
3. UNIX for Dummies Questions & Answers
Hello
We had an old system designed in fortran that ran on a IBM RS6000 AIX 3.2 system. The person who designed is long gone. It was replaced with a completely different (non unix) system 6 years ago. We still used it for historical lookups of older information. Well yesterday it died. The... (5 Replies)
Discussion started by: billfaith
5 Replies
4. Solaris
How to find the process that is using the port 80 and apache server.
When i used the command 'netstat -a|grep 80' it given that port 80 is in listening mode.
I had used the following command:
telnet localhost 80
GET /
I had got some HTML script.
But when I accessed the GUI ( url is... (7 Replies)
Discussion started by: vamshikrishnab
7 Replies
5. Shell Programming and Scripting
Hello all,
I would be happy if any one could help me with a shell script that would determine all the processes running on a Unix server and post a mail if any of the process is not running or aborted.
Thanks in advance
Regards,
pradeep kulkarni.
:mad: (13 Replies)
Discussion started by: pradeepmacha
13 Replies
6. Shell Programming and Scripting
suppose there are in 10 different server
how can i know in which server a process (ex:oracle )is running (6 Replies)
Discussion started by: alokjyotibal
6 Replies
7. Red Hat
Hello
Im using redhat and try to debug my application , its crashes and in strace I also see it has problems , but I can't see any core dump
I configured all the limit ( im using .cshrc ) and it looks like this :
cputime unlimited
filesize unlimited
datasize unlimited... (8 Replies)
Discussion started by: umen
8 Replies
8. Red Hat
What do you check????
Thanks!
JC (0 Replies)
Discussion started by: 300zxmuro
0 Replies
9. IP Networking
If Freebsd DNS server that served 100 people is crashed. How to move this 100 people to a new FreeBSD DNS server as quickly as possible? (1 Reply)
Discussion started by: AIX_30
1 Replies
10. Solaris
Hi,
I have two Solaris 10 servers. First server crashed last week (Monday) and second one crashed over the weekend. I have checked the logs such as /var/adm/messages, syslog and dmesg. So for I found none. My management wants to know why the server crashed. I need to come with some kind of... (4 Replies)
Discussion started by: samnyc
4 Replies
LEARN ABOUT DEBIAN
lwresd
LWRESD(8) BIND9 LWRESD(8)
NAME
lwresd - lightweight resolver daemon
SYNOPSIS
lwresd [-c config-file] [-C config-file] [-d debug-level] [-f] [-g] [-i pid-file] [-m flag] [-n #cpus] [-P port] [-p port] [-s]
[-t directory] [-u user] [-v] [-4] [-6]
DESCRIPTION
lwresd is the daemon providing name lookup services to clients that use the BIND 9 lightweight resolver library. It is essentially a
stripped-down, caching-only name server that answers queries using the BIND 9 lightweight resolver protocol rather than the DNS protocol.
lwresd listens for resolver queries on a UDP port on the IPv4 loopback interface, 127.0.0.1. This means that lwresd can only be used by
processes running on the local machine. By default, UDP port number 921 is used for lightweight resolver requests and responses.
Incoming lightweight resolver requests are decoded by the server which then resolves them using the DNS protocol. When the DNS lookup
completes, lwresd encodes the answers in the lightweight resolver format and returns them to the client that made the request.
If /etc/resolv.conf contains any nameserver entries, lwresd sends recursive DNS queries to those servers. This is similar to the use of
forwarders in a caching name server. If no nameserver entries are present, or if forwarding fails, lwresd resolves the queries autonomously
starting at the root name servers, using a built-in list of root server hints.
OPTIONS
-4
Use IPv4 only even if the host machine is capable of IPv6. -4 and -6 are mutually exclusive.
-6
Use IPv6 only even if the host machine is capable of IPv4. -4 and -6 are mutually exclusive.
-c config-file
Use config-file as the configuration file instead of the default, /etc/lwresd.conf. -c can not be used with -C.
-C config-file
Use config-file as the configuration file instead of the default, /etc/resolv.conf. -C can not be used with -c.
-d debug-level
Set the daemon's debug level to debug-level. Debugging traces from lwresd become more verbose as the debug level increases.
-f
Run the server in the foreground (i.e. do not daemonize).
-g
Run the server in the foreground and force all logging to stderr.
-i pid-file
Use pid-file as the PID file instead of the default, /var/run/lwresd/lwresd.pid.
-m flag
Turn on memory usage debugging flags. Possible flags are usage, trace, record, size, and mctx. These correspond to the
ISC_MEM_DEBUGXXXX flags described in <isc/mem.h>.
-n #cpus
Create #cpus worker threads to take advantage of multiple CPUs. If not specified, lwresd will try to determine the number of CPUs
present and create one thread per CPU. If it is unable to determine the number of CPUs, a single worker thread will be created.
-P port
Listen for lightweight resolver queries on port port. If not specified, the default is port 921.
-p port
Send DNS lookups to port port. If not specified, the default is port 53. This provides a way of testing the lightweight resolver daemon
with a name server that listens for queries on a non-standard port number.
-s
Write memory usage statistics to stdout on exit.
Note: This option is mainly of interest to BIND 9 developers and may be removed or changed in a future release.
-t directory
Chroot to directory after processing the command line arguments, but before reading the configuration file.
Warning: This option should be used in conjunction with the -u option, as chrooting a process running as root doesn't enhance
security on most systems; the way chroot(2) is defined allows a process with root privileges to escape a chroot jail.
-u user
Setuid to user after completing privileged operations, such as creating sockets that listen on privileged ports.
-v
Report the version number and exit.
FILES
/etc/resolv.conf
The default configuration file.
/var/run/lwresd.pid
The default process-id file.
SEE ALSO
named(8), lwres(3), resolver(5).
AUTHOR
Internet Systems Consortium
COPYRIGHT
Copyright (C) 2004, 2005, 2007-2009 Internet Systems Consortium, Inc. ("ISC")
Copyright (C) 2000, 2001 Internet Software Consortium.
BIND9 June 30, 2000 LWRESD(8)