For anyone who’s used MRTG and found it a little cumbersome to configure, then Cacti solves that for you.  It’s a definate first step to monitoring your network and systems, and once you start adding the plugin architecture and plugins, then it’s the next few steps as well.

The quickest and easiest way to get a copy of Cacti ready is using the CactiEZ  from Cactiusers.org . The CD has the most useful plugins installed and configured and will install straight onto a PC (warning it will erase all data, so make sure thats definately a spare PC).

I’ve also had CactiEZ running in VMware although I recommended this only for testing, as if you start using the Threshold plugin you will want Cacti to be your eyes and ears, so a physical server near the centre of your network is probably the best place.  If your really get into Cacti then you probably want to build your own server to run it on, so that you can manage updates to the server’s core components Apache, PHP, MySQL and NET-SNMP.

One final note is that the CactiEZ uses a 1 minute poll interval, and the default Cacti install uses a 5 minute poll interval.  Watch out for that one, as it may mean that some templates that you download will need a slight modification using the CDEF function.

Otherwise it’s definately go Cacti.  I’ve been using it for 4 years, and in that time have monitored Cisco, 3com, Linux, Windows, VMware ESX and a whole host of other devices.  If any of our supported learning providers need some further advise on monitoring their networks/systems you know where Hefin and I are….. Big clue?

I seem to be getting a bit of regular grief.  After updating VMware VirtualCenter I find that after a reboot it is no longer running and I have to go in and manually start the service.

Why? – well it’s because I’m using SQL Express so when VirtualCenter tries to start it can’t find the SQL server and therefore fails.

The little hack I’m using to fix this, is to go into the Registry Editor and under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\vpxd add MSSQL$SQLEXP_VIM to the DependOnService list.

Fortunately as VirtualCenter is just a management platform it doesn’t affect my running Virtual Machines/Servers.

I suppose I had better make my next “technical” post about something other than VMware!

We are in the process of trying to determine what technical training courses we should arrange to take place in Wales in the coming months.  If those from our supported learning providers would like to register their interest or suggest some possible courses we could run, then please use the following Google docs form.

We would also welcome any interest from others in the Welsh public sector.

Back in the summer (what summer?), VMware announced that they were making ESXi free.  A few weeks ago I decided to give it a go. I had my candidates ready and waiting – a pair of Dell PowerEdge 1850′s.  These have for the past two years been running Gentoo Linux and VMware Server for development and testing.

For my first attempt I plugged a USB stick in the hope that the installer would detect it and let me install to it – instead it just found the interal hard disks.  A quick search revealed this blog post.  I was of course able to skipp all the bits about downloading software, as I was doing this on a Linux machine which can mount iso images and has the commands tar, unzip and dd to hand. Remember that this process will erase all data on the USB stick.  You should also ignore VMware’s Marketing departments references to “32MB footprint”, as you will need about 700mb to install ESXi onto a server -  so a 1GB USB stick to you and me.

With in a few moments I had an ESXi server booted up. Using the menu on the servers to enter my IP details, and set a root password, I was then able to browse (https://) to the server and download the client software from the server.  Although, as the client software is identical to that for VMware Infrastructure, I already had a copy installed.  If your wondering what firewall ports you need open to access the ESXi server then it’s TCP 443, 902 and 8333.

Next step was to create a datastore. To do this I had to erase my existing hard disks to create some VMFS volume’s.  Now to install an OS onto a new virtual machine you either need the CD in the local drive of the ESXi server, or the client machine. Alternatively, you can browse to the datastore and upload an ISO file. Personally I took advantage of the NFS support in ESXi and used a nearby Linux server which has some free disk space. This means I can download the ISO’s onto the Linux server straight from the web, rather than having to upload them, as well as share those ISO’s between the two servers.  If your not that confident with Linux then you could probably download and use a copy of FreeNAS on a spare server to perform this task.

This free version of ESXi has support for NFS, as well as SAN’s (FibreChannel and iSCSI). One configuration pointer is to setup NTP on the server so that your Virtual machines (once you have Vmware tools installed) are able to keep good time. On the networking side, as with the paid for ESX/ESXi, you are able to use VLAN trunks into the servers from your network switches.

I was also impressed that I could use the VMware Converter on my paid for VirtualCenter server to copy shutdown VM’s from my paid for ESX servers into my free ESXi servers.  To a copy of a running machine then I simply cloned it on the paid for ESX server and exported the clone.  Although this is more features of Vmware Infrastructure/VirtualCenter than of this free ESXi product.  You can download a free starter edition of VMware Converter which should allow you to convert existing physical machines.

There are of course some limitations, you can’t add your Free ESXi servers  into VirtualCenter (if you have it), which means that you have to manage them by connecting directly to the server with the client software, this then of course means that you need accounts on the server (unless your happy just to use the root account). Once you have put your license key into ESXi then it removes the evaluation messages, but it also disables VMware Consolidated backup (vcb) support.  Without vcb and without a copy of VMware Converter Enterprise, then I can’t see any obvious way to get copies of your VM’s out.

To me it looks like this free ESXi is perfect for anyone starting to look at visualization, or looking to use it for development purposes (where you are dedicating server hardware to the task). It’s also an easier migration path than using VMWare Server, you can effectively turn the server into a full blown ESXi server by just changing the license key.  However, there is still potentially the issue of your VM’s being locked in – if you chose to give up on ESXi completely, but thats not much different to the lock-in from using physical server(s).

There is still of course a place for VMware server, it is perfect for running on a laptop or workstation, as it runs on top of the host OS and so will run on most hardware. We use VMware server on laptops for technical training courses, in fact we will be using it later in October for this event.

If your looking to see if your spare bit of tin will run ESXi then look here 

VMware ESXi can be downloaded from here

If you think that the 5 minute average from Cacti is not granular enough, try STG, a SNMP traffic grapher that can plot per second traffic graphs, or any other SNMP OID.

See : http://www.wtcs.org/informant/stg.htm for more details.

Came across this one again today….

If you notice Exim being slow to give out it’s 220 banner (particularly from the other side of a Firewall) then you might wish to tweak the following in your configure file (/etc/exim/exim.conf if your a Gentooist)

rfc1413_query_timeout = 30s

I believe it’s by default in the configure lowered to 5s (you can set also to 0s to turn the function off)

Another sign might also be a large number of “Connection reset by peer” messages in your mainlog file (/var/log/exim/exim_mainlog in Gentoo)

Just upgraded our VMware ESX nodes to 3.5.0 build 110268 / ESX 3.5 Update 2. Had been a little cautious about upgrading, especially after a lot of people got their fingers burnt by the Timebomb Incident.

The update fixed the issues we had trying to use vcbSnapAll to backup running VM’s. We were able to backup Windows 2003 and Fedora Core VM’s, but it failed on our Gentoo ones. Will be sharing the solution once I’ve got it running a bit smoothly.

I’m also liking the Health Status page (although a little concerned about my warning which must be false positive!)

– What can I say little things….little minds!

I suspect you will need your HP Management Tools (or similar) installed for these to display.

Managed to get WordPress-MU installed. Had to use version 1.3.3 for the LDAP integration to work. Works with Active Directory pretty easily (well for someone who’s had a stab at LDAP a few times and can remember what needs to be in each field!)

Thanks to Tom in the System team here at the University for pointing me in the right direction

WPMU-LDAP Plugin

Whilst we are on about LDAP and Active Directory. I was wondering how I could cheaply/freely make our systems more resilient in the event of a Domain Controller falling over. I settled for using domaindnszone.myaddomain.local as the hostname as it has the IP’s of both of my DC’s. Obviously you will need to replace “myadddomain.local” with your Active Directory domain – Not sure how well it works? – shall have to (virtually) unplug a DC and find out.!!!