Comments on: Is agent-based or agentless monitoring best? http://www.xaprb.com/blog/2008/08/21/is-agent-based-or-agentless-monitoring-best/ Stay curious! Thu, 09 Feb 2012 09:56:43 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Ivan http://www.xaprb.com/blog/2008/08/21/is-agent-based-or-agentless-monitoring-best/#comment-15405 Ivan Tue, 18 Nov 2008 11:02:10 +0000 http://www.xaprb.com/blog/2008/08/21/is-agent-based-or-agentless-monitoring-best/#comment-15405 Have author heard about Zabbix (www.zabbix.com)? It supports either agent-based or agentless-based monitoring, supports decentralized monitoring (proxy-servers) and many more nice features. P.S.: this is not an ad, i'm just a user of this system Have author heard about Zabbix (www.zabbix.com)?
It supports either agent-based or agentless-based monitoring, supports decentralized monitoring (proxy-servers) and many more nice features.
P.S.: this is not an ad, i’m just a user of this system

]]> By: Sheeri K. Cabral http://www.xaprb.com/blog/2008/08/21/is-agent-based-or-agentless-monitoring-best/#comment-15058 Sheeri K. Cabral Mon, 25 Aug 2008 03:09:48 +0000 http://www.xaprb.com/blog/2008/08/21/is-agent-based-or-agentless-monitoring-best/#comment-15058 <I>what happens when you have 1000 servers each running an agent, consuming 1000 times however much memory and other resources, and opening 1000 security holes simultaneously when a flaw is found? What if the central system dies — is your agent-based system smart enough that the agents don’t all have to be reconfigured to talk to its replacement?</I> Well, firstly, how do you install 1000 servers? 1000 agents? I've never been at a place that has manged over 200 servers that is still installing servers by hand; some kind of jumpstart/cfengine or kickstart/puppet combination is used (to create and maintain servers). In this way, reconfiguring or even reinstalling 1000 servers is not difficult at all, and I had to do this years ago while working at a university (jumpstart/cfengine there) when apache and openssl both had vulnerabilities. Also, how easy is it to restore your monitoring server from a backup (assuming you're taking a backup)? Is it harder to scp a configuration file 1000 times, if the central server dies, or is it harder to build a new servers and add in 1000 configurations? It's much more likely that you have an easy way to set up 1000 machines that have a common agent, than you have an easy way to set up 1 (or 2) central monitoring servers. (this is based merely on the fact that in your environment, you've found a solution to installing and configuring 1000 machines because there are so many of them, and you probably built the monitoring server by hand). And my final question -- why nagios *and* cacti? Cacti has the ability to monitor and page (including dependencies), as well as graph -- so why nagios as well? what happens when you have 1000 servers each running an agent, consuming 1000 times however much memory and other resources, and opening 1000 security holes simultaneously when a flaw is found? What if the central system dies — is your agent-based system smart enough that the agents don’t all have to be reconfigured to talk to its replacement?

Well, firstly, how do you install 1000 servers? 1000 agents? I’ve never been at a place that has manged over 200 servers that is still installing servers by hand; some kind of jumpstart/cfengine or kickstart/puppet combination is used (to create and maintain servers). In this way, reconfiguring or even reinstalling 1000 servers is not difficult at all, and I had to do this years ago while working at a university (jumpstart/cfengine there) when apache and openssl both had vulnerabilities.

Also, how easy is it to restore your monitoring server from a backup (assuming you’re taking a backup)? Is it harder to scp a configuration file 1000 times, if the central server dies, or is it harder to build a new servers and add in 1000 configurations? It’s much more likely that you have an easy way to set up 1000 machines that have a common agent, than you have an easy way to set up 1 (or 2) central monitoring servers. (this is based merely on the fact that in your environment, you’ve found a solution to installing and configuring 1000 machines because there are so many of them, and you probably built the monitoring server by hand).

And my final question — why nagios *and* cacti? Cacti has the ability to monitor and page (including dependencies), as well as graph — so why nagios as well?

]]> By: Rob Young http://www.xaprb.com/blog/2008/08/21/is-agent-based-or-agentless-monitoring-best/#comment-15051 Rob Young Thu, 21 Aug 2008 14:13:46 +0000 http://www.xaprb.com/blog/2008/08/21/is-agent-based-or-agentless-monitoring-best/#comment-15051 Baron, Thanks for your post on this, I think we agree that client vs agent-based architectures both have pros/cons depending on the environment to be monitored. No need to go into the details here, my thoughts are hashed out in my earlier posts. Ryan T. makes some good points on how the MEM agent easily enables advanced use of the MySQL Proxy; talking with customers, this is what most are looking for in terms of agent-based extensibility. Thanks again for the lively debate, RobY Baron,
Thanks for your post on this, I think we agree that client vs agent-based architectures both have pros/cons depending on the environment to be monitored. No need to go into the details here, my thoughts are hashed out in my earlier posts. Ryan T. makes some good points on how the MEM agent easily enables advanced use of the MySQL Proxy; talking with customers, this is what most are looking for in terms of agent-based extensibility.

Thanks again for the lively debate, RobY

]]> By: Mark Leith http://www.xaprb.com/blog/2008/08/21/is-agent-based-or-agentless-monitoring-best/#comment-15049 Mark Leith Thu, 21 Aug 2008 13:21:47 +0000 http://www.xaprb.com/blog/2008/08/21/is-agent-based-or-agentless-monitoring-best/#comment-15049 Oops, that was to Rohit, not Baron. Oops, that was to Rohit, not Baron.

]]> By: Mark Leith http://www.xaprb.com/blog/2008/08/21/is-agent-based-or-agentless-monitoring-best/#comment-15048 Mark Leith Thu, 21 Aug 2008 13:19:45 +0000 http://www.xaprb.com/blog/2008/08/21/is-agent-based-or-agentless-monitoring-best/#comment-15048 Hey Baron, I'm not sure how *anybody* could disagree with my pretty simple phrase of “Single central monitoring server == single point of monitoring failure”. ;) However, here goes: 1. What prevents someone from starting another instance of an agent-less monitoring tool and point to the same set of servers? - Nothing.. But.. You cause more load on the monitored server.. However again this is not a 'single central monitoring server'. 2. What happens when the agent fails? How does a single central monitoring server help? - Doesn't happen in MEM yet, but, having a system that can monitor from the agent *or* the central server is the right approach in an ideal world. Not many tools do this yet. 3. What happens when the agent starts consuming inordinate amount of memory and resources (as mentioned in the comment by Jason Cook)? You have no option left but to kill the agent. Keeping your production server alive is more important than running the monitoring agent! In an agent-less scenario a rogue application will not drain the resources of a production server. - Yes this *was* an issue in MEM (it stored all of it's collected data in memory until it could send it to the central server. Now it does not, it stores a backlog of x minutes, in a rolling window). What the agent needs now is to be able to raise alerts when the central server is down (sendmail, SNMP), as well as buffering the data collection to disk. Hey Baron,

I’m not sure how *anybody* could disagree with my pretty simple phrase of “Single central monitoring server == single point of monitoring failure”. ;)

However, here goes:

1. What prevents someone from starting another instance of an agent-less monitoring tool and point to the same set of servers?

– Nothing.. But.. You cause more load on the monitored server.. However again this is not a ‘single central monitoring server’.

2. What happens when the agent fails? How does a single central monitoring server help?

– Doesn’t happen in MEM yet, but, having a system that can monitor from the agent *or* the central server is the right approach in an ideal world. Not many tools do this yet.

3. What happens when the agent starts consuming inordinate amount of memory and resources (as mentioned in the comment by Jason Cook)? You have no option left but to kill the agent. Keeping your production server alive is more important than running the monitoring agent! In an agent-less scenario a rogue application will not drain the resources of a production server.

– Yes this *was* an issue in MEM (it stored all of it’s collected data in memory until it could send it to the central server. Now it does not, it stores a backlog of x minutes, in a rolling window). What the agent needs now is to be able to raise alerts when the central server is down (sendmail, SNMP), as well as buffering the data collection to disk.

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