When you purchase a vCluster in version 2, you will be faced with a single vCluster package option with a base subscription price of £5.00 per month. The package itself contains two products, one vCluster and a Shared Database, which are managed independently within the Control Panel and have their own add-ons and overage costs applied despite being part of the same package.

Each product can have a number of add-ons, ranging from the inclusive features such as SSH Access, Cron and FTP Access to adding additional usage limits to increase the number of FTP Accounts, Data Transfer and Disk Space available. All non-inclusive feature add-ons are charged on a monthly basis and as can be used to increase your base usage limits to reduce any possible overage costs incurred. This allows you to create the package required to suit your needs, instead of the restrictions of a pre-defined package.

Each month, at the end of your billing period an invoice is generated for you package. Your billing day is determined from the date that the package was purchased, each month after this you will be billed on that day (unless the next month has fewer days that your billing date, in which case the invoice will be brought forward to the next available date). The invoice consists of the subscription cost (£5.00) plus the price of any add-ons you have created and any overage costs incurred over the past month. It is important to note here that the subscription cost is paid for in advance for the forthcoming month, whereas any product add-ons and overage costs are charged in arrears at the end of the billing period (month) and will be shown as additional line items on the invoice.

Add-on packages, for example an additional Shared Database, are different from the product add-ons mentioned previously and can be created and attached to an existing vCluster package. Although these add-on packages are linked to your package they are essentially separate packages and will be billed for individually. This means they could potentially have a different billing date and the generated invoices have no relation to the parent package.

Hopefully this post has successfully outlined the changes in structure to packages in version 2 and has began to prepare you for the upcoming changes. In conclusion to this short series of blog posts in the run up to version 2 we will be taking another look at the Control Panel that will be used to manage your vClusters, which has been designed in a way to implement the concept of products within packages outlined in this post.

Just before Sun was bought by Oracle, Solaris came in 2 flavours. Solaris and Opensolaris. As the name suggests, OpenSolaris was open source and Solaris was the closed source variant. OpenSolaris was to become proper Solaris some day and development was to be made in the open. Because OpenSolaris was opensource, many different projects were born out of it. Nexetnta made a storage appliance. Belenix was a generic desktop with KDE. StormOS was a simple desktop with Xfce. FreeBSD which had lost it’s edge to Linux over the years, took the chance and ported ZFS with great success. Joyent based their cloud 100% on Opensolaris. They even offer their version, called SmartOS, free to download and use in production.
Alas, Sun was bought by Oracle, Oracle closed the Solaris source code and open development of OpenSolaris ended.

Or did it?

Just before Oracle closed the OpenSolaris source, a group of hardcore Solaris sysadmins and companies using OpenSolaris for their business decided to create a distro of OpenSolaris, called OpenIndiana. Their aim was to collaborate and move the platform forward and avoid Oracle and their heavy handed policies altogether. The result was Illumos, which is the kernel, and OpenIndiana which is the full generic server grade OS that OpenSolaris was.

So what choices did we have for ZFS storage?

One obvious one would be OpenIndiana. For all intents and purposes, it is the continuation of OpenSolaris. It is a stable platform, it has features beyond ZFS that are not found in any other system (i’ll talk about these later), but it has a flaw. Familiarity with the platform is very low. Solaris in general and by extension OpenIndiana where nowhere near as popular as Linux of FreeBSD. For one person familiar with Solaris you could find fifty familiar with Linux.

Another option was Nexentastor. Nexentastor is an Illumos distro that is commercially backed by a company called Nexenta. With Nexentastor one can make a storage appliance out of practically any PC less than 2 years old. Familiarity with the platform is not an issue because the user/admin interacts with the appliance through a web interface. It is a purpose built system just for creating storage appliances.

Another option was FreeNAS. FreeNAS is practically the same as NexentaStor, but using FreeBSD underneath instead of Illumos. Just like NexentaStor, FreeNAS is a purpose built operating system with a nice web interface on top.

The last option was FreeBSD. FreeBSD is the father of practically all UNIX and derivatives, going back to the late 70′s. Over the years it has gained a reputation of stability that any other platform would be envious of. Just like OpenIndiana, not many people are familiar with FreeBSD.

So why did we choose OpenIdiana in the end?

First lets compare the different solutions based on some general features:

As you can see NexentaStor and FreeNAS are almost identical in features, especially if one takes in account commercial support.

One of the things we will use extensively in vCluster is ZFS send/receive. This is a ZFS feature where a snapshot of a filesystem can be sent locally or over the network to another ZFS server and have an identical replica of the data remotely. Note that this is not the same as rsync, because rsync syncs files, whereas ZFS syncs blocks. This is significant because ZFS will send the difference in blocks, which means that syncs are significantly faster than rsync, plus they are checksummed.
This rules out NexentaStor, for now at least, because we are not prepared to pay a license for such a basic feature of ZFS.

Having that in mind, I started evaluating FreeNAS. The system I used has a Quad Core Xeon Processor @ 2.5 GHz, 32GB RAM, 22 2.5″ 7200rpm 750GB SATA disks and 2 OCZ 32GB SSDs used as ZFS zil accelerators (or slogs or logzillas as some ZFS engineers call them). It also has 3 Adaptec RAID 5805 controllers.
One thing to note is that ZFS hates RAID controllers with a passion. If you have to use a RAID controller configure it so as to present the disks as JBOD or at a minimum configure each disk as a RAID0 array with a single member. Remember that ZFS is a volume manager combined with a filesystem. It also handles RAID, having single parity, double parity, triple parity, mirror and stripe modes of operation.

So back to FreeNAS, I configured the system, I setup the network and I started benchmarking. We need the system to perform well as an NFS server for Linux clients. So I used a system in the lab that has 8GB RAM, 2 250GB SATA disks and a Quad Core Xeon @ 2.5 GHz, as an NFS client.

Initially I wanted to establish the speed of the FreeNAS server locally. So I run iozone, which is included with FreeNAS, to see just how fast the system I built was. After some fiddling around with the various iozone options I ended up running the following test: iozone -az -g 2G /mnt/tank/test -b /mnt/tank/iozone.xls
This command runs iozone in automatic mode, trying block sizes from 4K up to 16384K and writing and reading a file that starts from 4K in size up to 2GB in size.

The result was the following:

Sequential write:

Random write:

Hmmm. What is happening here? Sequential writing and random writing at 4GB/s?? How is it possible to write a file randomly at the same speed as writing it sequentially?!?
The answer is that ZFS is caching and using RAM so aggressively that if not told otherwise it will eat up *all* RAM minus 1GB by default. Yep, you read that right, all RAM minus 1GB. So the graphs in reality show the speed that the ZFS caching subsystem work. Also note the jump in performance when the benchmark reaches 128K block size in the first writer test. This is because this is the default block size when you create a zfs filesystem.

Ok then. How can we eliminate caching so we can see how the system really performs?
Simple. just add -o to iozone, so that it forces the system to actually write every single time to stable storage before it continues. So what do we get now?

Sync writer

Random sync writer

What is this? Again sequential write and random write go at the same speed?!?
If you remember I created the ZFS pool with 2 zil accelerators, slogs from now on. These are used by ZFS exactly when something wants to write to the system using sync. These SSDs can push 75000 IOPS, which translates to ~550MB reads and ~500MB writes per second. Not bad. and if you notice the graphs go up almost linearly with the block size.

Here are some reader stats that go off the scale. I used the SSDs as read caches now.

Reader

Random Reader

Note the speed when the file size is the same as the block size. 10GB/s!! This is straight from RAM.

This is all fine you say, but you want this to be an NFS server!
OK then here it is:

Linux NFS writer performance:

Linux NFS random writer performance:

Again this makes no sense!! 2.5GB/s from the network? This is impossible! The server uses one nic at 1Gbit/s. This translates to a theoretical maximum of 100MB/s, not 2.5GB!!!
Well you see, Linux caches too. To solve the conundrum look at the green line lower in the graphs. This is the 2GB file being transmitted through the network. You will notice that it is going constantly at 1/5th of 500MB/s, which is equal to 100MB/s! This is because the Linux computer does not cache the 2GB file, so it writes it directly to stable storage, in this case the NFS export from FreeNAS.

So then, we have established that the server is more than adequate to cope with the load expected from vCluster and we have established that it can saturate a 1GB network link. So why did we not use FreeNAS?

The answer is xattrs. You see, in vCluster we use SELinux extensively, which relies on xattrs so do its job. It turns out that FreeBSD and by extension FreeNAS do no tsupport xattrs at all!

How annoying.

In the next blog post I will continue with benchmarks and more on OpenIndiana.

There are lots of systems we could use to serve NFS. There is Linux of course, FreeBSD, OpenIndiana and a slew of commercial solutions from companies like EMC, NetAPP, HP, Dell etc. Looking around and testing various solutions we decided that Openindiana is the best solution for our needs. The main reason is ZFS.

Some background

ZFS is a filesystem originally developed by Sun Microsystems. It was released in late 2005 in the development builds of Solaris. When it was released it obliterated anything freely available at the time. It had features that where not even in the radar of other filesystems.

Some of the features are:

• Block level checksumming
• Real-time block level compression
• Cheap snapshots
• Copy-on-write
• Atomic operations
• Deduplication
• Practically infinite capacity (can address pools of 256 billion terabytes in size)
• Intelligent and aggressive caching, making use of dedicated accelerator block devices
• Remote replication of filesystems and snapshots
• Blatant layer violation (I will explain this further down)

One could look at this list and see features that other filesystems have. For example snapshots are generally available in other systems through different mechanisms e.g. LVM in Linux. Checksumming (only metadata) is available in XFS. No stable filesystem has all of them though.

In my view, ZFS has two main advantages that no other system has, which stem from the features above. The first one is that it never needs fsck (or scandisk for you windows users). The second is simplicity.

Fsck

Fsck is one of the most annoying things that a sysadmin can face. First it is slow. If a 10TB array has to check its filesystem a sysadmin (and of course clients!) has to wait needlessly hours and hours for it to finish. Downtime goes up, people get annoyed and in the end fsck might fail because of a million different reasons – not enough RAM, too many errors, a disk dies while fsck is running etc.
ZFS does not need any kind of fsck because of the atomic nature of its transactions and because every block is checksummed. This means that on disk data is *always* valid.

Simplicity

The second reason that sets ZFS apart from other filesystems is, in my view, simplicity. This comes from the dreaded “Blatant layer violation”. What this means is that ZFS ignores the separation of different subsystems that other operating systems use to manage their disks and filesystems. Let me give you an example to illustrate this better:

In Linux you have fdisk to partition the drives, then md to create a RAID array, then LVM to create the physical volumes that you will then chop up in logical volumes and finally mkfs to format the volumes with the desired filesystem. So if you have 3 drives and want to create a RAID5 LVM array you will have to do the following:

fdisk -l
mdadm --create /dev/md0 --level=5 --raid-devices=3 /dev/hdb1 /dev/hda1 /dev/hdf1
pvcreate /dev/md0
vgcreate lvm-raid /dev/md0
lvcreate -l 57235 lvm-raid -n lvm0
mkfs.ext4 /dev/lvm-raid/lvm0
mount /dev/lvm-raid/lvm0 /mnt

In the case of ZFS the equivalent commands are:

format
zpool create tank raidz c2t0d0 c2t1d0 c2t2d0

End of commands. (format is a Solaris command used just to find the name of the drives e.g. c2t0d0, which could be in Linux /dev/sda)

Really. Nothing more is needed.
The reason is that ZFS combines a volume manager with a filesystem. This eases administration, which in turn leaves room for less errors and which leads to better optimization and of course easier and faster troubleshooting.
So where is the catch, you might ask. There has to be some caveat somewhere.

There is one actually.

All the features of ZFS need computing power. This means RAM and CPU. This means that in order for ZFS to have the same performance as other, may I say lesser filesystems, it needs to run on a significantly bigger box than the competition. These days CPU speed and RAM are cheap, so this argument is getting thinner every day.

In the following days I will continue with the comparison of the different systems that support ZFS and with some very interesting benchmarks.

When the sticks arrived, I opened one of them and I noticed something strange. The stick was smaller, lighter, the logo was a bit off and the colour of the stick was different.

Spot the fake:

Thinking that it was just my eyes playing up, I plug the stick into my Ubuntu 12.04 powered laptop. Nothing happens, no nautilus pop-ups, no nothing. Then I notice that load went from 1 to 3 almost immediately!
I start looking at syslog and I see the log being full of:

udevd[4731]: timeout: killing '/sbin/blkid -o udev -p /dev/sdb' [4841]
udevd[4731]: timeout: killing '/sbin/blkid -o udev -p /dev/sdb' [4841]

Initially I thought that I had stumbled upon some strange bug in Ubuntu. I plug the stick in a Mac and it works perfectly. Disk Utility said that it was an 8GB stick and I created a new fat partition. I plug it in Ubuntu again hoping it would work now but the result was the same. Load jumps to 3 immediately and the stick is not accessible. I look at the messages more closely and I see:

Direct-Access   FlashDis FlashDisk

FlasDis??

I insert my own stick and I see: Direct-Access Corsair Voyager.

Suspicious, I grab the box that the stick came in and look closely at the fine print:

2008 Coesair. I look at the other sticks and they are all the same! Coesair! Not, Corsair!

I plug the stick in Ubuntu again and I run fdisk -l but it is blocked. cfdisk the same. Only Disk Utility in Ubuntu works and it says that the stick is 1.5GB is size.

Wait. 1.5GB??
I plug it in a FreeBSD box I am working on in the lab and again it says 1.5GB.
This is it then. The stick reports wrong size and Ubuntu and FreeBSD get confused when trying to access the drive and discover that it is actually a different size. lsusb reports 0011:7788. Google points me to the right direction where I find that this is a more common problem that I thought: Fix Fake Flash

I would bet that these sticks could also be virus infected.
In conclusion, when you buy sticks always check that the stick you received is actually the stick you ordered and not some cheap virus infected knock-off.

See you in my next post where I dive deep in ZFS, FreeBSD, Openindiana and much more!

The first version of the CatN vCluster was built from an engineering point of view: it was feature rich but hard to maintain, stable but not designed for customers to interact with day-to-day. A team of web developers were brought into the project to develop a control panel which made a large part of the backend engineering code accessible to users and it was this which was launched as the vCluster public beta. This is the system which the majority of CatN vCluster clients currently use. However, while this system proved a large number of the key vCluster technologies, there were still a number of problems with the system which needed to be ironed out. Firstly there was a large amount of  duplication in the management layer of the system and, while users didn’t see it, a number of settings were stored in multiple locations requiring each to be updated when any changes were requested. There were also speed issues with the control panel, as well as a number of other technical problems meaning the system required quite frequent maintenance. So in March 2011 a second round of development work started.

Development of vCluster version 2 alpha was driven much more by how users needed to interact with the system. It removed the layers of duplication making day-to-day tasks simpler and quicker. Indeed the speed of the v2 alpha interface was infinitely better than that of the v1 interface. It was also the playground for a number of new technologies — the underlying way the hosting stack worked was re-engineered — as well as a testbed for some new pricing models. The v2 alpha was previewed in July 2011 at WordCamp UK and received some very positive feedback. It was released to testing around the same time and currently hosts some of Fubra’s biggest traffic sites. There were still improvements to be made, however, and a lot more development work was undertaken in the run up to v2 beta.

Development of v2 beta began very early in 2012. It took the very best parts of both v1 and v2 alpha and rolled them into one system. Development again was driven by user interfaces with a focus on powerful, intuitive functionality. The control panel was completely re-written from the ground up. The backend web hosting stack became a hybrid of the previous two versions as well as receiving a number of improvement. An improved caching layer was added and a number of features were introduced to the control panel which removed the need for the level of manual intervention required by the previous control panel builds. Feedback was taken into account from both the preview of v2 beta and from current users of the v1 system and improvements were made. Along side this the billing model was tweaked to make vCluster even more cost effective to users across the board.

But there is still more to come. v2 beta still needs to mature. While we are confident it will out perform both previous versions, we want to make sure it is rock solid be before it is launched. We also have grand plans for the future — we know that once the control panel is being used by our remarkable customers, comments and suggestions will flow our way and while we intend to base our continued development off those ideas, we also have a number of developments on the drawing board we know our users will love.

The new vCluster and control panel is slated for launch over the summer months, but if you can’t wait to get a sneak preview of the latest developments in the control panel then you’ll want to check out Steve’s next blog post where he will guide you through some of the best bits of the new system.

The last time I checked, including vCluster 1.0, it has actually been for 2 years. Never fear though, we are rapidly approaching product launch and are in the final stages of development. As this mile stone draws closer the team and I have decided to put together a series of blog posts explaining the new vCluster version 2 beta, the development process we have gone through to get to this point, and to deliver a tour of the new control panel and product / packaging model.

This is the first post, and as Head of Product, I have written it to address the commercial and product feature elements of vCluster 2.0 from the user’s perspective.

What is vCluster?

vCluster is a managed PHP platform as a service (PaaS). This means that we manage every layer below the application layer of the server. For example, we manage the data centres, network, server hardware, server operating system and server software so that our customers can drop their PHP code in a folder and it ‘just works’.

A PaaS is perfect for users who do not want to (or may not possess the technical ability to) manage their own server and infrastructure. Essentially it is plug and play managed hosting which doesn’t require any additional input from the user beyond uploading their website files for it to work.

Specialising in PHP hosting means that each vCluster comes with a MySQL database and supports applications with LAMP system requirements such as WordPress, Joomla! and Drupal. It is also a great platform for bespoke PHP applications, for example our parent company Fubra is hosting one of their PHP applications9 AffJet on a vCluster.

The vCluster code is deployed on a cluster of physical and virtual servers allowing users to benefit from economies of scale commonly associated with shared hosting. This means we are competitively priced whilst still offering a plethora of powerful features commonly associated with VPS or dedicated hosting.

How much does it cost?

At face value this is an easy one; £5 per month! vCluster has a base monthly subscription of £5 per month for the single vCluster package. This charge creates the vCluster account and allocates the initial resources to the account, for example a MySQL database and block of storage.

In addition to the base vCluster subscription data transfer and processing time is charged for on a utility basis similar to a gas or phone bill. We are yet to finalise the price of these units but will be announcing it as soon as possible.

One of the key things about the new pricing structure is that we have done away with the prescriptive small / medium / large packages of vCluster 1.0. This has allowed us to fairly charge purely for the resources used by our customers, and not oversell; it allows our users to design a vCluster that perfectly suits their needs. This decision was made following beta tester feedback and user feedback from events such as WordCamp UK.

Now that we have a single package we give users the option to add / enhance functionality through add-ons. At launch we will offer the option of additional MySQL databases, multiple FTP users, remote MySQL access and additional storage, but we plan on adding many more add-ons in the weeks following launch. I see the add-ons model as a great way of allowing users not only customisation of our hosting package, but also as a way to add value by integrating partner services with our hosting products in the future.

What features will it have at launch?

We are currently in a development feature freeze so what you see here is what you will get. We are aiming to focus on feature adding following launch with additions such as email, and domain name registration integration.

• Dedicated static IP address with every account.
• SSL support and certificate sales.
• Static content caching and customisation with Varnish.
• Access to error, FTP and access logs on the server and via the control panel.
• Multiple sites host-able on a single vCluster account.
• On demand backups of your vCluster.
• Multiple access options with FTP and SSH.
• Cron jobs for automated operations. Manageable through crontab or the control panel.
• A custom built control panel developed especially for vCluster and other CatN products.
• It feels like a managed VPS for only £5 per month!

Coming soon…

Now that I have introduced vCluster version 2.0 beta from the commercial / product perspective you can expect another two posts in the coming days. Jonathon, Head of Infrastructure, will be describing the development process leading us to this point. Steve Whitely, Head of Platform Services will finish the series with a summary of the new product packaging structure and a tour of the new control panel.

Of course, as we approach launch we will keep you updated with progress and let you know when we open for business again, making accounts publicly available for organic sign ups.

My expertise lie in the following areas, and as my title would suggest I am a specialist storage architect focusing on building scalable, highly available storage clusters to various requirements depending on the project.

• Extensive experience in the setup, maintenance and ongoing administration of Linux (Ubuntu, RedHat, Debian), Solaris 10, Open Solaris, FreeBSD and Windows Server 2003-2008 operating systems.
• Setup, maintenance and ongoing administration of Oracle, PostgreSQL and MySQL databases.
• Administration of Java application servers such as Tomcat and Glassfish to enterprise requirements and standards.
• Setup, maintenance and ongoing administration of SAN, NAS and other network storage.
• Design and implement custom ZFS storage solutions on Opensolaris/Illumos and FreeBSD.
• Web Server clustering, using Apache with pound as the load balancer and caching using Varnish.
• Extensive experience of creating Private Cloud type architecture based on XEN and KVM.
• Setup, configuration and ongoing maintenance of high traffic, critical mail servers.

I have been working in the IT industry for over 20 years and of course have worked on various projects. Some of the most notable are as follows.

• Setting up and maintaining the ClubSeat website, client CRM and ERP systems.
• Setup and administration of the Greek Ministry of Finance Export Registry Systems.
• Building and maintaining the server infrastacture for the iPhone application Plaisio, and consulted OTE for it’s webhosting business based on Parallels Zirtuozo containers.
• A European Union project involving people with dementia, based on the Ecosystem home automation software. Setup and administration of all server infrastructure and remote setup of the Ecosystem on client’s computers.

I’m looking forward to hearing from the CatN testers, and (after we officially launch) our users. Send me an email if you would like to discuss vCluster storage or ask me any other questions, alex@catn.com.

As I am a student of Digital Media Design at Bournemouth University, Fubra is just the sort of company that would coincide perfectly with the skills that I am currently developing at uni. The friendly, accepting community of employees that work here and the environment in which they work make this place an easy transition from the uni world to the full-time employment world.

I was expecting to be working on a web design project when I joined the team at Fubra but instead I was given the task of producing a short promotional, informative video/animation to raise awareness of Cloud Hosting and its benefits over computer hardware servers. I was happy to accept this challenge as I had worked with Adobe Flash CS5 at university, and the idea that we had for the video would also give me an opportunity to develop my skills with Adobe After Effects CS5.

The project is coming along really well and I’m hoping that it will be finished by the end of this week. I’ve really enjoyed working at Fubra and would be happy to come back in the summer to complete my required 4 weeks of work experience.

- Jake Wigmore.

I’ve been in one of the DC’s moving a SAN and installing servers, helping me get a better understanding of the hardware side of the business, as well as getting the lowdown on the existing services and services being launched over the next 6 months. I’ve also got to grips with writing wiki articles and learnt the basics of wiki mark-up language.

I’ve met the team and I think I know everyone’s names now, thanks for bearing with me guys!

Going forward I’ll be working to bring the pCluster service to market, developing and managing the service and ensuring it is sufficiently differentiated within the market. I’ll be looking to add value to the product, meeting clients and championing the service to generate interest from potential customers. I’ll also be assisting the product commercial team day-to-day to ensure customer requirements are understood and delivered.

I’ll be working closely with Joe Gardiner to bring pCluster to market by the end of the summer and generate marketing buzz around it in the run-up to the product launch. The pCluster product will build on the success of vCluster and offer a competitive private cloud hosting solution for businesses and public bodies, giving the benefits of security, high availability, backup solutions, replication and load balancing tailored to your needs, with support from a team of dedicated hosting experts.

There are a number of blogs out there that will explain to you how to install a WordPress Multi-Site on your localhost, but they’ll use the sub-folder method, which is fine but I like working from the root. So I’ll try to explain why I use a multi-site install, how you can use it and will explain how to get it working on your localhost with sub-domains.

Why Have a Multi-Site Install

One strong advantaged of working with a WordPress MultiSite install is versioning of WordPress’. Although I’ve not tested this to see if it would be any good or if it would work across every recent versions but for those hardcore developers who wish to test with regards to versions, this maybe a good idea.

Any who, it’s handy to have a single WordPress install base rather than having the same files a number of times that you don’t really care about. When I was looking up last night on how to setup a local install with subdomains (such as sub.domain.com) there was no real documentation how to do it, it was all sub-directories (such as domain.com/sub/). This doesn’t really suite me as I work with sites from the root rather than the directory so I was desperate to find out how to do this, lucky for those reading this I did.

Setting Up the Host

This can be a little tricky and change depending on your (L/M/W)AMP stack and operating system, so I will try to cover the best I can with all three stacks; Linux, Mac and Windows.

1. Find your system host file and add your custom WordPress multisite install address (mine is mu.wp) by adding the line:
   127.0.0.1 mu.wp

   • Windows
     location: C:\Windows\System32\drivers\etc\host (make sure you can view hidden files and have admin privileges)

   • Mac
     `/private/etc/hosts` (use this tutorial for further instructions)

   • Linux
     `/etc/hosts` (use this tutorial for further instructions)

2. You might also want to add any sub-domains now to your host file as you will manually need to add each one; for now I just want to add boom.mu.wp, which is as simple as adding a space and typing in the URL next to your install address so you should have a line that now looks like this:
   127.0.0.1 mu.wp boom.mu.wp
   (When ever you want to add another sub-domain, just add it to the same line)

3. Find your Apache `httpd-vhosts.conf` file; head towards your Apache install folder and follow the path `conf/extra/httpd-vhosts.conf` (Windows requires admin privileges). Keep in mind; this might not be correct and if so, do a system file search for the file, or if you can’t find it then go to `conf/httpd.conf` (requires admin privileges)

4. Check that the line NameVirtualHost *:80 is included in that file, if not then add it.

5. Now add the the follow block of code (taking into account that some parts will need changing:

   <virtualhost *:80>
DocumentRoot "[FILE PATH TO YOUR WORDPRESS INSTALL]"
ServerName mu.wp
ServerAlias *.mu.wp
<directory "[FILE PATH TO YOUR WORDPRESS INSTALL]">
AllowOverride All
Options Indexes FollowSymLinks
Order allow,deny
Allow from all
</directory>
</virtualhost>

   To clairfy a few parts, `ServerName mu.wp` is the same as our host file name and `ServerAlias *.mu.wp` is the same again but we added `*`. as a prefix that acts as a wildcard, so anything will be accepted as a sub-domain pre-say

6. Now flush your DNS records and restart Apache (may not work for all installs of Apache, if that’s the case then you will have to look for the relevant documentation) and you can continue with the standard WordPress install

Installing WordPress Multi-Site

1. Install WordPress as normal keeping in mind the options you choose now will be used on that root domain (so mine is called MU with the address http://mu.wp/)

2. Once installed and working, head to your `wp-config.php` file and add the line define('WP_ALLOW_MULTISITE', true); above the line /* That's all, stop editing! Happy blogging. */

3. Go into your WordPress admin area hover over the menu item “Tools” and look for the option “Network Setup” and click on it

4. In the “Create a Network” page you want to select the “sub-domain” option and then click the “Install” button

5. You’re now presented with three things to do before your network is fully operational

   1. Create the blog.dir folder in the wp-content folder (that can be seen in the root

   2. Copy the contents of the first textarea and add it to the wp-config.php we previously edited

   3. Copy the contents of the second textarea and add it to the .htaccess file in the root of your WordPress install. Keep in-mind that file beginning with a . are seen as system files and thus are invisible so you may have to make it visible (here’s how to for various systems: Mac, Windows 7 and Vista, Linux). If you still can’t see it then you just need to create the file.

6. Log out and back into your WordPress admin area and you should see a new option under the “Dashboard” menu item, namely “My Sites”, this lists all the sites you have currently available to you in your network. Ignore that option for now and hover just above that to the “My Sites” in the admin bar, hover over “Network Admin” and click on “Sites”

7. You are now in a page with a similar style to the post/page view; here you can add a site, so click “Add Site” towards the top and fill in the relevant details (mine was for boom.mu.wp). You should be now able to access that new sub-domain.

That should be it; all you need to remember to do is add each new sub-domain you want to the `host` file. There are easier ways of doing, I for one use MAMP Pro on my Mac that handles all the Apache and `host` file configurations in a nice GUI. Not sure on Windows and Linux options that allow you to manage Apache using a pretty GUI, if you do though please share with us!