Monitoring your infrastructure – Zabbix

Tuesday, September 14th, 2010 | hardware, linux, useful tools | 2 Comments

Hi there – I’m afraid I’ve neglected the blog for the last few months – it’s been a busy spring and summer. I’ll try to post more regular articles now that the evenings are closing in again!

As you grow your infrastructure – one of the growing pains you’ll encounter is how to keep an eye on how your systems are running. Sure, you can come in every morning and login to each of your servers, maybe scan the logs and run a few commands like htop and dstat to verify that things are working ok. This approach doesn’t scale very well (it might work for 2 or 3 machines, but will be problematic with 50 machines). So you need something to monitor your infrastructure, ideally something that will do all of the following,

  1. Monitor all of your systems and notify you if there is a “problem” on any system.
  2. Store historical data for some key performance parameters on the system (it is useful to understand what kind of loads your systems normally run and whether these loads are increasing over time).
  3. Provide 1. and 2. via an easy to configure and use interface.
  4. Provide a nice graphical display of this data – for scanning for performance problems.
  5. Automatically perform actions on systems being monitored in response to certain events.

There are many open source and commercial applications for monitoring systems which meet the above requirements – see Wikipedia’s Comparison of network monitoring systems for a partial list of so called Network Monitoring / Management Systems.HP OpenView is the 800 lb gorilla of commercial network/system management tools but seems to have morphed into a whole suite of management and monitoring tools now. In Linux circles, the traditional solution for this problem has been Nagios. It has a reputation for being stable and reliable and has a huge community of users. On the other hand (based on my experiences while evaluating a number of different tools), it is configured with a series of text files which take some getting to grips with and a lot of functionality (like graphing and database storage) is provided through plugins (which themselves require installation and configuration). I found the default configuration to ugly and a little unfriendly and while there is a large community to help you – the core documentation is not great. There was a fork of Nagios, called Icinga which set out to address some of those problems – I haven’t checked how it’s progressing (but a quick look at their website suggests they have made a few releases). Kris Buytaert has a nice presentation about some of the main open source system monitoring tools from 2008 (which still seems pretty relevant).

After evaluating a few different systems, I settled on Zabbix as one which seemed to meet most of my requirements.  It is a GPL licensed network management system. One of the main reasons I went with Zabbix is because it includes a very nice, fully functional web interface. The agents for Zabbix (the part of Zabbix that sits on the system being monitored) are included in most common distributions (and while the distributions don’t always include the most recent release of the Zabbix agent, newer releases of Zabbix work well with older releases of the agents). Also, Zabbix is backed by a commercial/support entity which continues to make regular releases, which is a good sign. For those with really large infrastructures, Zabbix also seems to include a nicely scalable architecture. I only plan on using it to monitor about 100 systems so this functionality isn’t particularly important to me yet.

While our chosen distributions (Ubuntu and Debian) include recent Zabbix releases, I opted to install the latest stable release by hand directly from Zabbix – as some of the most recent functionality and performance improvements were of interest to me. We configured Zabbix to work with our MySQL database but it should work with Postgres or Oracle equally well. It does put a reasonable load on your database but that can be tuned depending on how much data you want to store, for how long and so on.

I’ve been using Zabbix for about 18 months now in production mode. As of this morning, it tells me it is monitoring 112 servers and 7070 specific parameters from those servers. The servers are mainly Linux servers although Zabbix does have support for monitoring Windows systems also and we do have one token Windows system (to make fun of ). Zabbix also allows us to monitor system health outside of the operating system level if a server supports the Intelligent Platform Management Interface (IPMI). We’re using this to closely monitor the temperature, power and fan performance on one of our more critical systems (a 24TB NAS from Scalable Informatics). Finally, as well as monitoring OS and system health parameters, Zabbix includes Web monitoring functionality which allows you to monitor the availability and performance of web based services over time. This functionality allows Zabbix to periodically log into a web application and run through a series of typical steps that a customer would perform. We’ve found this really useful for monitoring the availability and behaviour of our web apps over time (we’re monitoring 20 different web applications with a bunch of different scenarios).

As well as monitoring our systems and providing useful graphs to analyse performance over time, we are using Zabbix to send alerts when key services or systems become unavailable or error conditions like disks filling up or systems becoming overloaded occur. At the moment we are only sending email alerts but Zabbix also includes support for SMS and Jabber notifications depending on what support arrangements your organisation has.

On the downside, Zabbix’s best feature (from my perspective) is also the source of a few of it’s biggest problems – the web interface makes it really easy to begin using Zabbix – but it does have limitations and can make configuring large numbers of systems a little tiresome (although Zabbix does include a templating system to apply a series of checks or tests to a group of similar systems). While Zabbix comes with excellent documentation, some things can take a while to figure out (the part of Zabbix for sending alerts can be confusing to configure). To be fair to the Zabbix team, they are receptive to bugs and suggestions and are continuously improving the interface and addressing these limitations.

At the end of the day, I doesn’t matter so much what software you are using to monitor your systems. What is important is that you have basic monitoring functionality in place. There are a number of very good free and commercial solutions in place. While it can take time to put monitoring in place for everything in your infrastructure, even tracking the availability of your main production servers can reap huge benefits – and may allow you to rectify many problems before your customers (or indeed management) notice that a service has gone down. Personally, I’d recommend Zabbix – it has done a great job for us – but there are many great alternatives out there too. For those of you reading this and already using a monitoring system – what you are using and are you happy with it?

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Linux as a Home Theatre PC (HTPC) – Installation

Tuesday, February 23rd, 2010 | hardware, linux | 4 Comments

See Linux as a Home Theatre PC (HTPC) – Introduction for an introduction to using Linux as a HTPC. In this post, I detail the steps I used to actually install and configure the HTPC and some minor gotcha’s that cropped up in relation to audio over HDMI.

  1. Downloaded Mythbuntu 9.10 64-bit edition from the Mythbuntu site.
  2. Installed Mythbuntu using the standard configuration settings (I may reinstall with a different partitioning scheme in the future but for now, at least, I just need a partition in which to dump various bits of media).
  3. Connected the MythTV box to my HDTV using a standard HDMI cable.
  4. Ensure you are using the NVidia Restricted Driver version 180 (and not 173) in order for HDMI audio to work (there is also a newer version 190 driver but I haven’t verified that this works yet).
  5. During initial MythTV configuration, configured to use ALSA:hdmi for audo playback rather than the default. This is sufficient to have MythTV play video files loaded in /var/lib/mythtv/video correctly.
  6. While MythTV presents a nice interface, I would also like to be able to use the standard Ubuntu desktop from time to time (Mythbuntu installs an XFCE4 environment by default – you can install GNOME or KDE also if you wish but for occasional use, the standard environment works very well). To get HDMI audio working outside of MythTV (for example, when browsing), added the following to /etc/asound.conf
    pcm.hdmi_hw {
     type hw
     card 0     #  <-----  Put your card number here
     device 3   #  <-----  Put your device number here
    pcm.hdmi_formatted {
     type plug
     slave {
     pcm hdmi_hw
     rate 48000
     channels 2
    pcm.hdmi_complete {
     type softvol
     slave.pcm hdmi_formatted hdmi_volume
     control.card 0
    pcm.!default hdmi_complete

    and then went to Applications/Multimedia/Mixer and clicked on Select Controls and enabled IEC958 2 and hdmi_volume. Back in the main mixer window, select the Switches tab and enable IEC958 2. Sound over HDMI should now be working (thanks to for tips on this, configuring HDMI sound output can be a little tricky for now at least).

  7. ALSA includes a useful utility called speaker-test which you can use to test your sound output.
    speaker-test -Dplug:hdmi -c2 -twav

Of course this is an experimental system – so not everything works perfectly. In particular, the TV card is not currently picking up output from my UPC cable set-top box (the set-top box includes a standard TV aerial socket on the back which I’ve connected to the Hauppage PVR-150). When I tested the system with Mythbuntu 9.04, I detected a signal from this and could view some television channels (the quality was mediocre but I didn’t attempt any tuning or tweaking) and could use the system as a PVR / DVR – one of MythTV’s key features. Since installing Mythbuntu 9.10, I haven’t detected a signal despite some efforts to configure it. I suspect a kernel driver issue but I have yet to work my way through the IVTV troubleshooting procedure mainly because I’m not very interested in this functionality for the momet at least. It’s something I’ll investigate at some stage, although in the future – I’ll probably be more interested in adding a DVB-T card to the system to avail of Ireland’s Digital Terrestrial Television.

In conclusion – things that are working well include,

  • Video playback – both in the MythTVin frontend and from the XFCE desktop (using VLC or Totem).
  • Music playback,
  • HD playback including using VDPAU. During playback of some HD samples, processor load on the system remained negligible, suggesting that the bulk of the decoding activity is happening on the 9400 rather than on the cpu.

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Linux as a Home Theatre PC (HTPC) – Introduction

Tuesday, February 16th, 2010 | hardware, linux | 3 Comments

Hi – apologies for the recent hiatus, hibernation is coming to an end, should be posting more frequently again now (also currently experimenting with both twitter and buzz).

I recently started looking into using a Linux box as a media centre or HTPC. In the past I’ve experimented with so called “multimedia drives” as a solution for managing my collection of media recordings and archived media. The drive I was using was a Lacie Silverscreen and while it worked, it did have various limitations. In particular, it didn’t play HD media and it sometimes had audio sync issues playing back media that played without problems on the PC. I assume the sync issues were the product of either a lack of processing power in the Silverscreen or possibly a lack of codecs. Newer products from Lacie (or similar products from other companies like Iomega’s ScreenPlay) have probably addressed some of these issues and there is no doubt, if you’re a non-technical user, these multimedia drives are a good solution.

In the interests of learning more about how well Linux works as a media solution, I decided to go about building one with a view to installing MythTV on it and evaluating the suitability of a Linux box as a full-featured HTPC. The first step in this experiment was to identify suitable hardware for a HTPC – key requirements for me were,

  • Noise – as a machine sitting in your living room beside your TV, the HTPC needs to be quiet. This also suggests it should run cool, it means if you have any fans in the system they won’t need to run at a high speed and/or for long. Key considerations for sound are minimising the number of fans (preferring passive cooling options such as heatsinks if they work), sound reduction features in the box (such as sound insulation and things like rubber/silicone grommets for mounting hard drives, fans and so on).
  • Performance – I want the system to be capable of playing back all possible types of media including HD video. I’d also like to have the option of encoding new media on the fly while simultaneously watching  something else. All of this means that a reasonably powerful processor and a reasonably high performing graphics card are neccesary.
  • Size – as a further consideration, I’d prefer if the unit I build is reasonably small – ideally it shouldn’t be particularly visible in the living room beside or near the TV. For this one, I don’t plan to go to any heroic efforts so I’ll prefer a conventional case over anything amazingly small. As you reduce a PC in size, you start running into heat issues and you start having to use components that have been specifically designed for smaller units – which leads to increasing cost.
  • Cost – while not the main driver, I didn’t plan on spending excessively for any particular component of the system. Certainly, a good spec HTPC shouldn’t cost any more than a reasonble spec desktop PC.

After lots of research and review reading, I finally settled on the following spec (note that in February, 2010, at least some of this hardware is well behind the curve – if you’re building a new box now you can probably find improved components for at least parts of this),

I chose the motherboard, primarily for the integrated NVIDIA 9400 graphics chipset which provides a HDMI output on the motherboard and also includes support for HD decoding in the chipset (rather than requiring the main system processor – while there is some support for such decoding on chipsets from other vendors, the support for doing this in Linux seems to particularly good with the 9400 using VDPAU). Other components were mainly chosen either because they have a good noise profile or because they give good “bang for buck”. The processor is probably overkill but was relatively cheap and given this system is a testbed for various media experiments, I’d like to have enough processing power just in case. For a typical user, a lower spec processor would be more than sufficient. A similar comment applies to the memory, it is way more than I expect to use but for the price, it didn’t make sense to purchase less. Note that the memory is standard, boring, “value” memory – I’ve experimented with high performance memory in the past and it required various tweaks such as bumping the memory voltage in the BIOS and manually setting memory timings before it performed optimally (or at all) – life is too short for this and the performance gains for a typical user aren’t really noticable (but such memory usually features impressive go faster stripes if thats your thing!

As an aside, since I build this system – NVIDIA have released their ION graphics platform and Intel have released their Atom lower power processor range. These seem to provide the basis for a good HTPC type system (as far as I know, the NVIDIA ION platform is built around a version of the 9400 chipset so it should have similar functionality to my motherboard’s chipset) but I have some concerns about how suitable the Atom processor would be for heavier duty tasks such as transcoding. As always, there is a trade-off between performance and overall size – smaller systems have less room to dissipate heat so they need to run cooler (usually with a lower performance).

For my initial foray into the area, I decided to use Mythbuntu, an Ubuntu based Linux distribution which includes MythTV and is preconfigured to work well connected directly to a TV. Mythdora is a similar idea but based around the Fedora distribution. There is no reason not to install your favourite Linux distribution and install MythTV on top of it if you wish.
My initial experiments were carried out with Mythbuntu 9.04 earlier this year but I thought I’d reinstall with Mythbuntu 9.10 on it’s recent release and document my experiences here, including detailing what works and what doesn’t. See my next posting for details of how things went.

Update: Puzlar sent me a tweet asking what kind of remote control I used with the system. The Antec Fusion case comes with it’s own infrared receiver and remote control. The Hauppage PVR-150 also included it’s own IR receiver and remote control. Since the IR receiver in the Antec Fusion case doesn’t need any additional items to be plugged into the box, I opted to go with that. The MythTV wiki contains details of how to configure the IR receiver to work properly – when I installed Mythbuntu 9.04 it required some manual tweaking but when I installed Mythbuntu 9.10 it worked out of the box without any tweaking as far as I can remember – so the standard keys like the arrows and the play/pause/rewind/forward buttons on the control do what they should do in the Mythtv Frontend and you can move the mouse around the desktop using the control also (which is a bit slow but ok if you just need to point and click on something occasionally).  I also have a wireless mouse and keyboard (a Logitech S510 but it seems to have been discontinued in the meantime) for occasional surfing and tuning of the system. I recently tried out XBMC as an alternative interface for the HTPC and that supported all the remote control functionality too (perhaps more than MythTV out of the box) – XBMC looks like a nice alternative to MythTV if PVR isn’t a requirement – I’ll be playing around with it some more.

One other note on the case – the Antec Fusion is a nice case – maybe a little bigger than I expected but it does look more like a piece of HiFi kit than a PC so it blends in well beside the TV. While I thought an LCD panel on the HTPC would be useful, in retrospect I have no need or use for this and if I was going again, I’d probably order a case without an LCD – perhaps something like the Antec NSK2480.

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