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Service Level Agreement


We don’t think you should have to consider the procedure for what goes wrong when you choose a hosting provider – our reputation ought to precede us. However, over the years we have had some demand to create a firmer Service Level Agreement, and these terms represent a clarification of our existing practice – the way we put things right if they go wrong.


  1. “Bytemark”, “we”, “Us”, “our” means Bytemark Computer Consulting Ltd, The Raylor Centre, James St, York YO10 3DW,
  2. “Service” means any hosting or connectivity service offered by Bytemark, including but not limited to Virtual Machines, BigV machines, Dedicated Hosts or ADSL connectivity.
  3. “Customer”, “you”, “your” means you, the person or persons in whose name(s) a service is maintained by Bytemark.
  4. “Technical contact” means a person or persons nominated by the Customer with whom Bytemark can discuss all matters of a technical nature relating to the Service
  5. “Network” means the combined functionality of all routing, switching, cabling equipment and interconnect agreements under Bytemark’s ownership or control
  6. “Bootable” in the context of a hosting service means that the host in question has the ability to start up and run its normal functions – hosting web sites, receiving email or whatever other function the service has been set up to provide for the customer.
  7. “Working hours” means 9.30am to 5.30pm, Monday to Friday, excluding English bank holidays (see the BERR web site for the full list)

Service Level Agreement (standard)

This document describes the standard level of service that all hosting customers can expect from Bytemark. It attempts to quantify the levels of service that all hosting customers can expect, and the remedies we offer if we fail to provide service at those levels.

There are absolutely no circumstances in which Bytemark will:

  1. Guarantee a remedy for a single failure to meet this service-level agreement that exceed either a refund of 1/12th of a fee paid for annual hosting for an affected service, or a full monthly fee if the service is paid for monthly. This is referred to a as the “maximum monthly refund”
  2. Accept responsibility for consequential damages as a failure to meet the terms of this Service Level Agreement. It is the customer’s responsibility to ensure that the consequences of any such failure are foreseen, and a suitable backup plan in place where there may be financial consequences of a failure. Bytemark will always advise the customer on contingencies to the best of our abilities.

Unless stated in a supplementary service level agreement, Bytemark offers no guarantees on the correct functioning of software installed on any hosting product, and it is entirely the customer’s responsibility to maintain such software. This includes all standard security updates.

Bytemark temporarily suspends all guaranteed service levels for customers who have not settled invoices within the agreed terms.

Core network

You can expect our core network to be available 100% of the time – that is to say that our infrastructure will provide two-way traffic from any other properly-routed internet IPv4 address, to the IPv4 addresses allocated to your hosting product(s). ADSL tails are not considered part of our core network, and are subject to a separate part of this SLA (given below).

We acknowledge that anything less than 100% is a lapse in the service level that you expect. On request we will refund 10% of the maximum monthly refund for every full 30-minute period that the network connectivity falls below this figure, accumulated during any consecutive 30-day period.

We exclude from this guarantee lapses in service where Bytemark cannot communicate with IPv4 addresses from other organisations that are not properly routed at the time of the lapse; the following causes are some examples of where some global IPv4 addresses will end up as “improperly-routed” and excluded from our guarantee:

  1. another organisation misconfiguring its peering arrangements with Bytemark, causing its IPv4 addresses to become unroutable as a result
  2. failure or major changes in routing by a global “tier 1” transit provider, even where Bytemark are not direct customers of said provider
  3. misconfiguration of a hosting product by the customer (as detailed below)

No guaranteed service level is offered for connectivity to IPv6 addresses, as we do not feel that the global IPv6 network is reliable enough to offer such guarantees.

Hosting products (general)

All our guarantees on hosting are conditional on the customer’s hosting product being properly configured and maintained. Specifically this means that:

  1. Bytemark must have a Technical Contact available, either the customer or another party nominated by the customer to make minor configuration changes at our request which may be necessary to facilitate smooth running of our network
  2. your hosting product should not be “thrashing” (i.e. the system constantly using swap during normal operation)
  3. your hosting product should be completely under your control, and not have been compromised by a third party
  4. your hosting product should not be blocked from responding to ICMP pings over its network interface

If any problems arise with your hosting as a result of your hosting product not being maintained correctly, Bytemark cannot guarantee any particular availability or performance.

We may also need to perform maintenance on your hosting which we consider essential to the ongoing reliability of our network or hosting platforms, which we will attempt to warn you about at least 7 days in advance. Such maintenance is excluded from any guarantees of uptime where the customer has been warned 7 days in advance.

Hosting products (BigV machines)

These conditions are specific to hosting on our BigV platform.

You can expect your BigV virtual machines to be available for 100% of the time – that is to say that once you start a virtual machine running, it won’t stop running due to hardware faults.

If there is a failure of a BigV machine, providing the customer’s machine was “properly configured” at the time of a failure, Bytemark will refund 10% of hosting fees for every full hour that it is down or unreachable. We define “down or unreachable” as either the system not running at all, or running slowly enough that a static web fetch of 5KB or less, or a one-line SSH banner return takes more than 20 seconds to return.

You can also expect that the BigV management service will be available 100% of the time, that is to say you should be able to issue requests through any BigV client to create, delete or alter the specification of virtual machines at any time.

If there is a failure of the BigV management service, we will refund 10% of your BigV-related fees for every full hour that the service remains unavailable, or returning server errors.

Hosting products (virtual machine)

These conditions are specific to hosting on our Virtual Machine platform.

You can expect our virtual machine platform to be available for 100% of the time – that is to say that once running, it won’t stop running due to hardware faults.

However we may occasionally need to perform maintenance that will involve stopping or moving customers data, which can incur 30-90 minutes of down time for each virtual machine. Bytemark will endeavour to warn customers of such outages up to 3 days in advance, but the customer must acknowledge that this is not always possible in the event of sudden hardware problems.

If there is a failure of the service, providing the customer’s VM was “properly configured” at the time of a failure, Bytemark will refund 10% of hosting fees for every full hour that it is down or unreachable. We define “down or unreachable” as either the system not running at all, or running slowly enough that a static web fetch of 5KB or less, or a one-line SSH banner return takes more than 20 seconds to return.

Hosting products (dedicated server)

These conditions apply to customers who rent a dedicated server from Bytemark.

You can expect your dedicated host to be available for 100% of the time unless it has suffered a hardware failure. If your host suffers a hardware failure which brings down your hosting completely, you can expect Bytemark to repair or replace the faulty part within 4 working hours of your reporting it to us, or 24 hours at the outset if the failure occurs outside of 9am-5pm Monday to Friday.

If the hardware failure is not remedied within the stated times, we will refund 10% of your maximum monthly refund for every hour or part-hour that the host is not in a bootable state, up to a maximum of 100%.

Bytemark endeavour to spot hardware failures through various external checks on your server, but we rely on you to inform us if you encounter problems, and will discuss any potential problems you might spot through our normal support channels. We do not consider the 4 hour (or 24 hour) replacement period to have started until the fault has been correctly identified by Bytemark, or reported by the customer and subsequently acknowledge by Bytemark.

Service Level Agreement (Plesk)

This supplementary agreement applies to customers who pay a premium for the Plesk control panel on their hosting product, for whom Bytemark will offer some limited assistance in installing and maintaining it.

Bytemark expects that customers with Plesk will only control their hosting product through the Plesk interface, and not use the supplied root login details to make any significant alterations to the software setup. Any modifications made to a system running Plesk are at a customer’s own risk and may impact or complete remove Bytemark’s ability to provide software support.

Within these exceptions, Bytemark guarantee to do the following on the customer’s behalf:

  • maintain the correct licensing status such that the server continues to function for all future versions of Plesk;
  • advise on, and assist the customer in performing major operations such as upgrades and migrations
  • up to once every three months, perform some minor maintenance on the customer’s behalf which are not covered by the Plesk interface such as:
    • editing php.ini
    • clearing a mail queue
    • fixing DNS inconsistencies
    • applying system-level security updates
    • fix any minor setup issues caused by the Plesk software itself

Customers using Plesk remain completely responsible for the software that they install, and must take steps to ensure the security of their server when installing any new application on their server.

Bytemark will assist with any configuration or setup problems with Plesk, and may occasionally choose to ask the vendor to help with a particular problem where we suspect a fault with the Plesk software itself. We rely on the vendor to solve such problems for us, and where this proves necessary the customer may need to wait 3-4 working days to see a resolution to a particular problem.

Service Level Agreement (fully managed)

This supplementary agreement applies to customers who pay a monthly or annual management fee to Bytemark for additional support services in conjunction with one or more hosting products. It is intended to support one or more Application(s) which run across one or more hosting products, and which will be the focus of Bytemark’s concern.

Customers who have agreed a fully managed service with Bytemark should expect that Bytemark will charge an extra fee, to be negotiated depending on the application(s), and based on the likely number of hours per month and number of hosting products that need maintaining. In exchange Bytemark will take extra care over a particular customer’s application to ensure that, within the budgetary and operational constraints of the customer, will perform as well as it possibly can, with the lowest possible down time.

Bytemark reserve the right to raise the fee where more work than originally budgeted for has been done in a particular month, and will do their best to warn customers where such work is necessary to keep their application(s) running smoothly.

Bytemark will advise the customer as to the service level they can expect from their machine, and will endeavour to document the “worst case” scenario when it comes to hardware failure. Bytemark will always advise customers where a given set of operational or budgetary constraints from the customer may result in a particularly undesirable failure case.

Customers paying for a fully managed service can expect one or more of the following services as agreed when the fee is negotiated.

Installation and documentation

Bytemark will advise customers as early as possible as to how to plan their software installations, or, where the customer is planning their own software installation, will ensure that the plan is overseen and noted by one of Bytemark’s staff. Bytemark will make its software recommendations to suit the customer’s needs, but will always veer towards high uptime and simplicity of maintenance. Bytemark will also always recommend the minimum level of access to a production hosting system to ensure that customers themselves are not able to destablise their own hosting. Where customers have access to their own hosting, the customer must acknowledge that this introduces a risk that Bytemark cannot always plan for.

Installations of hosting products, whether performed by Bytemark or the customer, must be noted in detail by Bytemark to ensure that support and maintenance is easy to perform. This documentation forms a critical component of our managed hosting, and must be kept up to date. Bytemark must be informed of any significant changes made by the customer to any installations that Bytemark are expected to maintain.

Priority support

Customers with managed hosting agreements can expect responses to ordinary support requests within 4 working hours, and to urgent requests within 30 minutes of the request being issued.

Customers with managed hosting agreements can expect a single primary point of contact for their hosting requirements, who will answer questions and support requests when they are on duty.

First response

Where the First Response service has been specified, Bytemark will set up their own system to ensure that they are notified first of any service outages or performance problems that may affect the customer’s application(s). The customer can expect that Bytemark will investigate and respond to any problem, or potential problem, with their application, as soon as symptoms become apparent, 24 hours a day, 365 days per year.

Bytemark perform this service by ensuring that their monitoring service is aware of our customers’ applications, what services they should be serving up, and by testing important URLs associated with that application on a regular basis. Bytemark will also arrange to monitor common server diagnostics such as load, mail queue, database queries and anything else that might be relevant to the application(s) performance. Bytemark ultimately rely on the customer to inform them sufficiently about their application, and to make sure that the number and frequency of tests is sufficient for the customer’s needs.

Bytemark will treat a non-functional or partially functional site as an urgent support request, and respond within 30 minutes. Other faults that may indicate mere performance problems or application faults will be treated as ordinary support requests. All alarms will be reported to the customer with a diagnosis and recommendation.


Unless noted otherwise in a supplementary service level agreement, technical support is provided by Bytemark on a first-come, first-served “best effort” basis. We aim to at least acknowledge, if not fully answer, all emails to our advertised support addresses within 4 working hours.

We aim to answer the phones during working hours, but under times of high demand or staff sickness, may defer to an answering service where we promise to return all messages as soon as possible.