We've been doing a lot of load testing recently and are planning on doing a lot more, so we've developed a simple little script to make the collection of the vmstat (performance statistics) a bit quicker.

multivmstat is a php command line script which makes it easy to collect the statistics. Download the script

To run it you specify a list of servers to check:

This will run vmstat on each of the servers with a 5 second interval between samples.

It will create the following files:

Note: You mush have ssh access to each machine - ideally with a certificate so that no interactive authentication is required.

Download the script

I've been playing around with CakePHP again (I looked at it a couple of years ago) for a small site I'm working on.

I came across this lovely error though when trying to do a redirect:

I couldn't see anything wrong with the code - but a quick google found the solution - I had extra whitespace in the controller which was causing the problem.

Removing the extra whitespace after the closing ?> tag fixed it up.

Update: As Danilo pointed out below - this is not a cakephp issue, but a general php one, which occurs if you try to send headers after anything has been output to the browser.

Cheers, Mark

One of the nice things about Ubuntu is how easy it makes it to upgrade between versions - typically start up update-manager and it will prompt you if there is a new version available and handle all the details of the upgrade for you. I've done numerous upgrades this way and never had any issues.

However, I have a number of ubuntu servers which I manage and previously I have upgraded them by changing the /etc/apt/sources.list and then running "sudo apt-get dist-upgrade"

Today I discovered that there is an automated script to handle it - which I presume is what powers the gui version behind the scenes.

You need to make sure you have update-manager-core installed:

Then you simply run do-release-upgrade

I've just upgraded two different servers from Feisty as it has recently stopped being supported. I upgraded them to Gutsy and then to Hardy which is a Long Term Supported version. The whole process took about an hour of which it took about 5 minutes of my attention to answer a few simple questions.

Who said Linux is hard :-) Cheers, Mark

I just reinstalled my system with the latest Ubuntu 8.10 x64 and one of the apps I use regularly for testing and developing Asterisk applications is Twinkle, which is a great VOIP softphone.

It works great, but when I tried it in my new install the sound was all choppy, i.e. I would get every half of each second of the audio.

A bit of fiddling about with the settings and I got it solved. Posting it here so when I forget about it and run into the same problem again I'll know how to fix it.

The solutions is as simple as:

• From the menu select Edit -> System Settings.
• Select Audio on the left
• Change the audio devices to use the most approriate device that is NOT "ALSA: default: Default Device" - in my case it was "ALSA: plughw:0,0: HDA Intel (AD193x Analog)"

I do like the very friendly naming scheme for devices :-) Hope it helps, Mark

I just found this document on openfire properties settings so bookmarking it here for my own reference.

I came across it while debugging the socket connection timing out. After finding the property "xmpp.client.idle" which it mentioned had a default of 30 minutes, but after looking at the source code I verified it is actually 6 minutes.

One other point of interest - all these properties are stored in the db in the jiveProperty table.

Cheers, Mark

MySQL has some really useful functions that make timezone support a bit easier as described in a previous blog post..

However, you need to do a tiny bit of setup work before you can use the functions. You need to load the timezone info from your system into the mysql db.

Thankfully, the MySQL Developers have included a very handy script that will do just that from a zoneinfo files which are used on Linux and on Mac's.

Obviously change the mysql params or add a -p if you have a password or are connecting to a remote server.

Check out the MySQL developer site for full details on MySQL timezone support

Cheers, Mark

It should be simple to do this and it is. The hardest part was finding the correct way to do it, so for future reference:

Using the command line, you can use dpkg-reconfigure tzdata.

Follow the instructions to reconfigure the timezone. This was taken from the ubuntu wiki article

Cheers, Mark

While debugging some PHP code the other night I came across a particularly strange problem with MySQL Bit fields.

I was returning a query with some bit fields into my class but the it was not returning true or false when I switched the data.

A bit of hunting and it turned out the that it was being returned as a binary type and after a few failed attempts to convert it to an integer or boolean on the PHP side I found this bug report on it.

So the moral of the story is if you are selecting BIT types from a mysql DB in PHP don't do this:

Instead cast the bit to an integer in MySQL like so:

Voila, it works like expected.

Cheers, Mark Lynch

I was recently setting up a Ubuntu server and was partitioning it after it had been installed.

There was lots of free space on the drives as the root partition was only using a small portion of the disk. After running fdisk to partition it and mkfs.ext3 on the partitions to format them I couldn't see them in /dev/disk/by-uuid.

A quick google presented the solution:

According to the man page this makes udev request the kernel device uevents, which in essence makes it read the disk info again and show it all up so you can mount it happily.

Cheers, Mark

I've been working on getting CF Sandbox security working. It's trickier than I first thought so here's how to do it for future reference:

Enable security Manager

Instructions from Steven Erat's blog:

NOTE the example from the adobe site has the quotes in the wrong place. Note you also need to change [cf_webapp_root] to match the location on your machine.

Datasources

After I enabled Datasource security I began to receive the following error, a bit of digging reminded me that the MySQL connector tries to do some autoconfiguration for coldfusion to optimise it.

It was failing to load the configuration file which is inside the mysql connector jar file /com/mysql/jdbc/configs/coldFusion.properties

I haven't gotten to the bottom of why it couldn't be loaded but adding the following to the datasource query string fixed it up:

I would suggest adding some of the settings from this file as paramaters in your datasource settings as per previous post

Note: This was using the following:

• ColdFusion 7.0.2 Cumulative Hotfix 1 Multiserver install
• MySQL connector/J 5.0.8

Hope it helps. Cheers, Mark