Uni

tt ©

| w

ww

.uni

tt.c

om

Zero Data Loss Service (ZDLS) The ultimate weapon against data loss

Uni

tt ©

| w

ww

.uni

tt.c

om

Uni

tt ©

| w

ww

.uni

tt.c

om

The ultimate protection for your business-critical data

In the past, ultimate data protection was a costly issue, if not an impossible one. Enterprise so-lutions like MetroCluster are only accessible to large enterprises or multinationals because of their high cost. That’s a pity, because

the demand for this type of ap-plication grows every day. Unitt makes MetroCluster technology available to all through the Zero Data Loss Service (ZDLS). In this white paper, we will discuss how that works and introduce the

NetApp’s MetroCluster solution as well as Unitt’s ZDLS (Zero Data Loss Service) service that is based on it.

2

Data indeed play an impor-tant role in company processes. Your application data are your most precious asset and the cost of data loss can be very high. It is therefore crucial to ponder the question of what happens with your data in case of problems with your data centre. Perform a risk analysis of what can go wrong and what the (financial) consequences are for your company.

The answer to this think-ing exercise can be expressed through the RPO (recovery point objective) with which you deter-mine the maximum amount of time preceding a system failure for which you can afford to lose data without endangering the continu-ity of your business.

In many companies, ab-solutely none of the data are

expendable: the RPO is then 0. A solution to attain that level of certainty is synchronous replica-tion of your storage over several locations.

Uni

tt ©

| w

ww

.uni

tt.c

om

3

First of all, determine how important the availability of your data is

Uni

tt ©

| w

ww

.uni

tt.c

om

4

If you want to lose as little data as possible during a fail-ure, you have to replicate your data. For instance, if you have a web environment that processes customer transactions and saves those data onto its storage sys-tem (like e.g. a SAN or storage area network or a NAS or network at-tached storage), those same data are also simultaneously saved in another data centre. In case of a failure in the first data centre, the data will still be available in the second data centre.

Replication can happen in two ways and this determines the RPO. With synchronous rep-lication, saving a data set is only confirmed to the application (like e.g. a web server) when the set has been saved successfully in both data centres. This can slow down the application, because the network connection between both data centres induces a supple-

mentary delay and the application will wait until it has received the confirmation of successful saving. Data loss is however excluded: the RPO is 0 and you are certain that exactly the same data are present in both locations.

Another method is asynchro-nous replication. Here, the appli-cation receives a confirmation as soon as saving a data set to the first data centre has succeeded. If, in the meantime, a failure oc-curs in the first data centre, the data set may not have reached the second data centre yet and you are then at risk of suffering data loss. The RPO in this case is typically 15 minutes or more. In this scenario, the application runs faster because no supplementary delay is introduced.

The delay that is introduced by synchronous replication can be kept to a minimum by placing

both data centres close enough to each other. That is why, for this configuration, Unitt uses two data centres that are located less than 10 km apart. This still guarantees enough speed in your applications that replicate synchronously (all writing commands reach both SANs in a few milliseconds), while the distance is sufficiently long to avoid a local disaster could impact both data centres.

Synchronous or asynchronous replication?

One of the products that offer synchronous replication of data is MetroCluster from storage provider NetApp. This solution combines NAS and SAN technologies to synchronous replication to make your data available continuously and avoid data loss. MetroCluster offers the following benefits:

Uni

tt ©

| w

ww

.uni

tt.c

om

NetApp MetroCluster: the ultimate weapon against data loss

Continuous availability

The MetroCluster software expands NetApp filers to an array-based active-active storage clus-ter. This way, you don’t have to re-boot servers, restart applications or run failover scripts when your storage system fails in one of both data centres. In that event, the application isn’t influenced by the failure because storage has been active all the time in the second data centre. So, there is a trans-parent recovery from a failure.

One single system

Many replication solutions require that you manage, con-figure and maintain both SANs separately in both locations. That is somewhat sensitive to mistakes, because inconsistencies between the configurations may lead to errors that are hard to fathom. MetroCluster, however, is a truly clustered storage solution, where both SANs are managed as one single entity. In other words, the administrative overhead decreas-es, as does the risk of human er-ror.

5

Proven technology

NetApp MetroCluster has been tested in combination with virtualisation and clustering tech-nologies from VMware, Microsoft, Symantec, IBM and many others. Thanks to these partnerships of NetApp, MetroCluster can be in-tegrated flawlessly in your IT en-vironment.

Uni

tt ©

| w

ww

.uni

tt.c

om

6

In both data centres, you have virtual machines running in a VMware vSphere environment. If a problem occurs with a virtual server in one of the data centres, VMware will keep on running the virtual machine in a high avail-ability setup in the other data centre. You replicate the data with

MetroCluster. If something goes wrong with one of both SANs, no manual intervention is required in the vSphere environment: the IP address of the data automati-cally points to the SAN that is still in working order.

MetroCluster is an effi cient data protection system in many diff erent scenarios. Here are a few examples:

The MetroCluster solution applied in practice

1. A redundant VMware environment

Firewall node1 Firewall node2

MetroCluster node1 MetroCluster node2MetroCluster

Datacenter 2Datacenter 1

M

Geo-cluster

C

Geo-cluster

C

ESX node 1 ESX node 2 ESX node 3 ESX node 4 ESX node 5 ESX node 6

Uni

tt ©

| w

ww

.uni

tt.c

om

7

2. A cluster of database servers

Imagine you have a Microsoft SQL Server running of which you want to guarantee availability. You then run a database cluster of which the nodes are each located in their own data centre. The database servers share the same IP address, which is used

by the clients. If one of both data centres fails, the clients can reach the server that is still in working order via that IP address. By replicating the storage with MetroCluster, you can use the standard edition of SQL Server instead of the Enterprise edition.

The SQL Server indeed doesn’t need to know about the data replication: if one SAN fails, the IP address of the MetroCluster will automatically refer to the other SAN, in complete transparency with respect to the database server.

Firewall node1 Firewall node2

MetroCluster node1 MetroCluster node2

node 1 node 2 node 3 node 4 node 5 node 6

Database node1 Database node2

Firewall node1 Firewall node2

Geo-cluster

Geo-distributie

Geo-cluster

Geo-cluster

MetroCluster

Datacenter 2Datacenter 1

M

C

C

D

C

Uni

tt ©

| w

ww

.uni

tt.c

om

8

3. NFS or CIFS shares without data loss

accessible to your web servers. If one of both SANs fails, your fi les will transparently stay shared by the other SAN and no data are lost.

MetroCluster node1 MetroCluster node2MetroCluster

Datacenter 2Datacenter 1

M

Geo-cluster

C

Loadbalancer node 1 Loadbalancer node 2Geo-cluster

C

Application server 1 (A) Application server 2 (P)

By putting a NetApp fi ler in every data centre and replicating it with MetroCluster, you can share fi les without risk of data loss. In this case, you let the NetApp fi lers share your fi les via NFS (for Linux/Unix) or CIFS (for Windows) in order to make them, for instance,

Even though MetroClus-ter is a cost-effective solution in comparison with other solutions for storage replication, the in-vestment in the necessary infra-structure remains too important for many companies. That is why Unitt offers the technology “as-a-service” under the name ZDLS (Zero Data Loss Service): without any investment from your end, you gain access to MetroCluster technology for your storage, for a fixed monthly fee, including ser-vice and management, with SLAs up to four nines (a guaranteed resolution time of under 4,5 min-utes).

Unitt sets up all the layers of the solution redundantly and distributes systems and data over two top-notch data centres (Tier III+). There is optical fibre between both data centres, along two dif-ferent pathways over which runs 10 Gbit of Ethernet traffic. The SANs in both data centres save the data to each other in real time, so both data sets remain identi-cal – even if one data centre fails completely.

ZDLS offers you the following benefits:

Flexibility

You don’t need to invest in infrastructure and you will thus never lack storage or pay for too much storage. When your needs

for data capacity grow, you simply expand your storage on our ser-vice. In an OPEX model, you only pay for the capacity you truly use.

Quick entry

You can quickly enter into an advanced, proven technology with state-of-the-art components. You no longer need to invest time in setting up an infrastructure and managing it, but you can imme-diately entrust your data to Met-roCluster.

In the Benelux

Unitt offers you the guaran-tee that your data remain within national borders. Unlike other hosting service providers, we thus cannot be subject to an enforce-ment order from the American government to provide access to your data.

Partnership with NetApp

Unitt has developed a close partnership with NetApp, which allows us to gain access to the storage supplier’s best engineers. We can thus provide you with op-timum support.

ZDLS is available in two forms:

Fully shared environment

You pay on a monthly basis, per batch of 25 GB of synchro-nously replicated storage. Your

storage is located in an environ-ment that is also used by other clients, which helps minimise costs. Unitt manages and moni-tors the hardware and always has enough storage space in case of unexpected growth.

Dedicated shelves

This is the model you choose for very demanding applications. By using one or several personal shelves, you reserve the full ‘Input/Output’ of the storage disks en-tirely for your own organisation.

Uni

tt ©

| w

ww

.uni

tt.c

om

9

Zero Data Loss Service (ZDLS) as a cost-efficient alternative

Uni

tt ©

| w

ww

.uni

tt.c

om

10

With ZDLS, you can build a multi-data centre setup in a cost-efficient manner with LANs in the two data centres that operate as one single logical network. Unitt achieves this with a redundant optical fibre connection and also connects the data centres to the Internet in a fully redundant fa-shion. For this, we use BGP (Bor-der Gateway Protocol), with which

failure of an uplink is automatically compensated by the remaining connections.

A multi-data centre setup enhances the availability of your applications and data. So if you choose our ZDLS solution, your data will also be protected in a cost-efficient manner. In case of failure in one of both data centres,

you don’t lose any data. Both data centres are connected by a layer 2 network, so both SANs form one ‘local’ MetroCluster. The re-dundant server and network in-frastructure above it uses your storage as if it was one single SAN.

If you wish to avoid any risk of data loss, Unitt’s ZDLS is the answer. This solution based on MetroCluster is accessible to all and is thus more than a cost-effi-

cient alternative. It all starts with the most important question: how much data loss or downtime can your business afford?

Full redundancy thanks to the multi-data centre setup in ZDLS

Conclusion: zero downtime is within reach

Uni

tt ©

| w

ww

.uni

tt.c

om

About Unitt

About NetApp

Unitt provides high-end hosting solutions to satisfy the requirements of demanding business users. We develop and manage complex business hosting services using our in-depth knowledge of the latest technologies. Unitt was founded by Combell.

Unitt provides 24/7 support in your own language, direct contact with engineers who manage your in-frastructure, as well as rock-solid guarantees on service levels. The services, which include dedicated server environments and public and private cloud environments, rely on high-tech components.

http://www.unitt.com

NetApp creates innovative storage and data management solutions that deliver outstanding cost effici-ency and accelerate business breakthroughs. UNITT achieved Platinum status in NetApp’s Partner Program for Service Providers. Thanks to this, customers of both UNITT and NetApp can get the most out of all the features that NetApp’s technology has to offer and the services that UNITT adds as a service provider that is also a partner of NetApp.

http://www.netapp.com

11

Uni

tt ©

| w

ww

.uni

tt.c

om