Xen VPS Linux FAQ

Why Xen?

The Xen hypervisor is a unique open source technology that invented by a team at the University of Cambridge and is being developed co-operatively by the world's best engineers at over 20 major data center solution vendors.

With Xen virtualization, a thin software layer (known as the Xen hypervisor) is installed directly on the hardware, or "bare metal", and sites between the server's hardware and the operating system. This provides an abstraction layer that allows each physical server to run one or more "virtual servers", effectively decoupling the operating system and its applications from the underlying physical server.

Xen is exceptionally lean - less than 50,000 lines of code - which translates to extremely low overhead and near-native performance for guests.

Terminology

VM: Virtual Machine. Each customer has root access to their own VM which co-exists with other VMs on the physical host server.
Host Server. The physical Dell server which has multiple VMs running on it. Only Xtraordinary can adminster the host server.
VPS: Virtual Private Server. This is a common marketing term for a Virtual Machine. VPS = VM.

Can I upgrade between plans?

Yes. Just email us at support @ xtrahost.co.uk. There is no set-up fee but you are committed to the new plan level for at least a further month.

Depending on available host server capacity an upgrade may require moving your VM to an alternative host server. If this is required then 20-30mins downtime for your VM will have to be scheduled.

Can I add memory or disk space?

Yes, by upgrading to a higher specification plan.

How much of my allocated disk space can I use?

Out of your disk space allocation you must allow space for your linux distribution and space for any installed applications.

How much swap space can my VM use?

As standard we set up VMs with swap space equal to double the VM's physical memory (e.g. a VM256 plan with 256MB ram gets swap space of 512MB) up to a maximum swap space of 2GB.

How many Domains (.com, co.uk etc) can I host on a VM?

No limit.

Is a control panel available as an option?

cPanel is available at a cost of £8pm +VAT on a number of linux distributions.
cPpanel is only available at time of original order, it cannot be added later unless a full reinstall is requested.

Otherwise if you have the appropriate license you may install webmin, direct admin etc.

Who is responsible for backing up the VM?

Each night Xtraordinary will back up an LVM image of the server. The most recent daily and most recent weekly full backup is stored at any given time.

How many VM are on each physical server?

Typically each server has around only 4-6 VMs hosted per processor core. Each host server has 16GB of physical memory of which 4GB is reserved for the host Xen system and 12GB is assigned to VMs.

Memory, rather than processor resources, is typically the constraint on performance for a VM. Our Xen host servers run under low CPU load.

Which Datacentre are the Xen VM Servers Hosted In?

All new Xen plans are currently hosted in Interxion's London City Datacentre.

What version of Xen are you using?

Currently new VMs are running Xen 3.1 with a 2.6.18 kernel

Do you offer IPv6?

Not at present. Let us know about your IPv6 needs.

Are my IPs shared with other customers?

No. Each VM has its own assigned IPs.

How many IPs can I have?

Each VM has two IPs included as standard. If you require more you can request additional IPs subject to providing suitable technical justification (e.g. use for SSL Certificates). There is no charge for additional IPs.

Will IPs assigned be consecutively?

Yes, except for cPanel orders or where a prior special request has been made.

Can you give me IPs spread across lots of different subnets?

We can split the IPs between two different "Class C" blocks on request. We will not accommodate requests to spread IPs across a wide range of subnets.

What are acceptable reasons for requesting additional IP addresses?

Any service that needs its own unique IP.
Acceptable reasons can include: - SSL certificates. - Secondary DNS server.
Where it is possible to run services on different port numbers you should do that, do not request additional IPs for services that could quite easily run on a single IP with different port numbers.

Can I specify my Reverse DNS assignment for IPs?

Yes, this information is collected during on-line sign up.

Do you offer free trials or money back guarantees?

Trial periods will be considered on a case by case basis. Email sales @ xtrahost.co.uk outlining the purposes your VM will be used for.

Do you offer Windows VPS hosting?

Yes, more details are available on our Windows VPS hosting website .

What technical support is included?

If you have evidence of VM reliability issues due to problems with the host server, we will support you in troubleshooting those issues.

Technical Issues NOT supported:

• Performance and reliability issues related to your software applications.
  
• Installing linux.
  
• General linux advice.

How will I receive my root password?

During our SSL secured on-line signup process you will be requested to select your own root password. Your root password must be at least 8 characters long and contain a mix of alpha and numerical characters. We do not send passwords in plain text emails.

Do you monitor the servers?

We monitor the host physical servers. Customers are responsible for monitoring their VMs.
 

What are the Setup Timescales?

• VM orders received Monday to Friday before 3pm will typically be completed the same day by 6pm.
• VM orders received after 3pm Monday to Friday will typically be done the next business day before 6pm.
• VM orders received after 3pm Friday and through the weekend will typically be completed by Monday 6pm.
• Above timescales are subject to completing credit card verification and authorisation procedure (where applicable). Orders flagged for additional verification will be subject to delay. We may ask you to send copies of government issued identification (e.g. passport, drivers license) or copies of your credit card.  

Is there a Service Level Agreement (SLA)?

Yes, a 99.9% SLA applies to Xen VPS services.

In the event of the total periods of Downtime, due to failure of the hosting service, in a calendar month during the Term, exceeding 0.1% of time in said month a service credit will be made. One full day's credit of the Service Fee will be given for each hour of Downtime beyond the 0.1% allowable, up to a maximum credit of 100% of the month's Service Fee.

The maximum overall service credit payable due to Downtime in any calendar month will be 100% of the month's Service Fee.

Acceptable Use Policy

See our full Terms and Conditions. AUP highlights:

• No adult content permitted.
• No antisocial behaviour permitted (e.g. SPAM, spamvertised sites, scanning, illegal content..)
• No public IRC.