This guide gives information about how to build an Ozeki NG SMS Gateway
cluster to have a redundant SMS system. Clustering can be used to increase
performance or to be prepared for hardware failures. In this text a failover
cluster is discussed which can be used to prepare for hardware failures. If you
setup a failover cluster your system will provide better uptimes and better
tolerance against hardware related errors.
Before we begin the configuration of Ozeki NG cluster using Microsoft Windows Server 2003,
I will show you our own Ozeki Cluster software product which
allows you to setup a cluster configuration easier than using Microsoft's solution.
Figure 1 -
Ozeki Cluster is responsible for protecting your service against
hardware failure and reach higher availability of your Ozeki NG SMS Gateway software. Ozeki Cluster automatically
moves any service to another computer in case of a hardware failure. You can download it from
the following website: Ozeki Cluster
In the following part of this guide you will show how to configure your Windows Server 2012 R2.
Prerequisites
To setup clustering Ozeki NG SMS Gateway should be installed on
Windows Server 2003 Enterprise Edition or Windows Server 2008. Clustering
is based on Microsoft Cluster Server technology, so concerning hardware,
please refer to the Microsoft Cluster Server Administrator's Guide for a
list of supported hardware configurations and hardware configuration information.
In brief you will need hardware, that provides shared storage facility, and at
least two physical computers that will form Node 1 and Node 2 of the cluster
(Figure 1).
Figure 1 -
Figure 1 - Physical scheme of an Ozeki NG SMS Gateway cluster
Introduction
Unlike other clusters which are made for better performance, Ozeki NG SMS Gateway
clusters are used to increase availability. The goal of a highly available system
is to provide continuous SMS service, regardless of planned or unplanned
interruption. High-Availability refers to a system uptime that approaches 100%.
For example, an availability level of 99.999%, calculated on a round-the-clock
basis, would mean that an organization would experience at least five minutes
of unscheduled downtime per year on its Ozeki SMS gateway platform. A level
of 99.99% translates to 52 minutes of downtime. A level of 99.9% translates
to 8.7 hours, and a level of 99% equals about 3.7 days of downtime per year.
The need for high-availability is not limited
to 365x24x7 environments. In many cases an Ozeki NG SMS Gateway system must be
available during normal business hours or for a critical time periods throughout
the day. A system failure during these critical periods is unacceptable for
many organizations.
An Ozeki NG SMS Gateway cluster is based on the Microsoft Cluster Server
technology. It only presents the option of failover clustering, which means
that if a failure occurs on a server that is a member of the cluster (on Ozeki
NG SMS Gateway Node 1 or Ozeki NG SMS Gateway Node 2) the SMS service that
the failing server was hosting will automatically restart itself on another
server that is a member of the same cluster. The process of a service moving
from one server to another is called Failover.
Definitions
The Ozeki NG SMS Gateway service that the cluster runs uses resources of the
cluster nodes. The SMS service running on the cluster has its
own Harddrive assigned to it (which is shared with the other failover cluster
nodes),
it has its own IP Address and it has its own Network name. All of the resources
that a clustered Ozeki NG SMS Gateway service uses are called a Resource Group.
The Resource group contains the basic resources that the Ozeki NG SMS Gateway
service needs, Disk Drive, IP Address, and the service itself. All of these
together form a virtual server that can be moved from one server to another in
a matter of seconds (Failover) without any dependence on a specific server.
The user that accesses this virtual Ozeki NG SMS Gateway server will be exposed
to it like to any other Ozeki NG SMS Gateway installation.
Shared storage
To setup a fault tolerant Ozeki NG SMS Gateway cluster, the first thing to do,
is to build a shared storage facility. This facility should have a disk subsystem
that uses RAID (Redundant Array of Independent Disks).
RAID refers to the grouping of individual hard disks in a way that provides
continued operation in the event of a disk failure. The shared storage you
setup for an Ozeki NG SMS Gateway cluster can be both hardware RAID (e.g., a
RAID controller is used) and software RAID (e.g., the functionality is provided
by an operating system or application). There are many forms (levels) of RAID:
RAID-0: Stripe set without parity. Stripe sets work well with databases
due to the usually random I/O nature of database transactions. In RAID-0,
data is divided into blocks and spread (in a fixed order) across all of
the disks in an array. RAID-0 improves read/write performance by spreading
operations across multiple disks, so that operations can be performed
independently and simultaneously. While RAID-0 provides the highest
performance, it does not provide any fault tolerance. If a drive in a
RAID-0 array fails, all of the data within the stripe set becomes
inaccessible.
RAID-1: Mirroring. Disk mirroring provides a redundant, identical copy
of a disk. Data written to the primary disk is also written to a mirror disk.
RAID-1 provides fault tolerance and generally improves read performance, but
it may also degrade write performance. Because dual-write operations can
degrade system performance, many mirror set implementations use duplexing,
where each mirror drive has its own disk controller. While the mirror
approach
provides good fault tolerance, it is relatively expensive to implement.
In addition, only half of the available disk space can be used for storage.
The other half is needed for mirroring.
RAID-5: Stripe set with parity. RAID-5 provides redundancy of all data
on the array, allowing a single disk to fail and be replaced, in most cases,
without system downtime. RAID-5 offers lower performance than RAID-0 or
RAID-1 but higher reliability and faster recovery. RAID-5 uses the
equivalent of one disk for storing the parity strips, but distributes the
parity strips across all the drives in the array. The data and parity
information are arranged on the disk array so that they are always on
different disks.
There are other implementations of RAID, such as RAID-0+1 (aka RAID-10), RAID-2,
RAID-3, etc., but these are typically proprietary implementations unique to the
hardware manufacturer that support them.
When you build the shared storage facility, make sure, that all shared disks,
must be physically attached to a shared bus. Verify that disks attached to the
shared bus can be seen from all nodes. This can be checked at the host adapter
setup level. (Please refer to the manufacturer's documentation for
adapter-specific instructions.)
SCSI devices must be assigned unique SCSI identification numbers and properly
terminated, as per manufacturer's instructions. All shared disks must be
configured as basic (not dynamic). All partitions on the disks must be
formatted as NTFS.
Network connectivity
Each node of the SMS Gateway cluster should have two network adapters, one for
connection to the public network and the other for the node-to-node private
cluster network. If you use only one network adapter for both connections,
your configuration is unsupported.
Installation
During the initial installation, please make sure that you install the same
Ozeki NG software version on both nodes of the cluster. Concerning the
installation path, all files should be installed to the shared disk resource.
Installation steps:
Install a supported Windows OS and accept the default application choices.
After you have installed the Windows OS on the first node and before you
install MSCS, click Start, point to Programs, point to Administrative Tools,
and then click Configure Your Server.
Click Advanced\Cluster Service, and then in the right pane click Learn More.
In the Windows Help menu, review item 2 in the "Windows Clustering" topic.
Follow the instructions in the "Windows Clustering" topic to install MSCS.
Important You must read the "Planning for Windows Clustering\Requirements" for
server clusters and follow the checklist for server clusters named
"Checklist: Creating a server cluster". The "Checklist: Creating a server
cluster" topic is located under the "Server Clusters section\Checklist" for
server clusters topic.
After you successfully install MSCS, you must configure MSDTC to run on a
cluster.
On the Start menu, point to Programs, point to Administrative Tools, point
to Cluster Administrator,
and then click View Groups\Cluster Group. If the group contains an MSDTC resource,
proceed to step 9. If the group does not contain an MSDTC resource, complete
the following two steps.
On the Start menu, click Run. In the Run dialog box, enter the command cmd
and then click Ok. In the Command Prompt window, on the command line, enter:
Comclust.exe
Repeat step 7 on the remaining nodes of the cluster, one node at a time.
Install Ozeki NG SMS Gateway on all cluster nodes.
Activate Ozeki NG SMS Gateway on all cluster nodes.
Declare Ozeki NG SMS Gateway as a cluster resource.
Bring the Ozeki NG cluster resource online.
Test the cluster functionality by opening the SMS gateway configuration
GUI from a browser using the IP address of the cluster.
Additional information
One more thing to consider when you install your SMS gateway cluster is the
possibility of a power outage (which could cause both nodes to restart at
the same time). To ensure that both nodes of the cluster never start
at the same exact time, change the Boot.ini file timeout value of one node
to 10 seconds and change the value of the other node to 90 seconds. This
gives one node plenty of time to "get ahead" of the other node, and prevents
the computers from competing for the shared disks, which could cause a failure.
Common tasks
Shutdown: To shutdown Ozeki NG on a cluster, you need to user the
"cluster.exe"
command, that comes with the Windows OS. The basic syntax for this command is:
Version upgrade: To upgrade Ozeki NG SMS Gateway in your cluster to a new
version in an active/passive configuration, you need to install the new version
on the primary node only. The installation will update all files on the shared
storage. The service registration of the old version (on the passive node) will
work for the new version as well.
Changing service account: In some scenarios, for example in an SQL to
SMS gateway configuration, you might need to change the service account of the
OzekiNG service. This might be requested by your database administrator to meet
database login policy requirements. Please note, that if you try to change
service account information, such as the account name or the password, while
OZEKI NG SMS Gateway is clustered, the service cannot start when you try to
bring the cluster group online. In this scenario, you may have to manually
remove Ozeki NG SMS Gateway completely from both nodes, and then reinstall
SQL Server.
Alternative clustering technologies
An alternative to the introduced clustering solution can be created using
Vinca's Co-StandbyServer, that is available at http://www.vinca.com/products/sbsnt/ntco_ds.html,
you can also use Vinca's Octopus (http://www.legato.com/Products/octopus.html),
or you can go for Network Specialists' Double Take (http://www.nsisoftware.com/main/pages/Products/DTspec.html).
For shared storage solutions, you may NCR's LifeKeeper (http://www3.ncr.com/nt/lifekeeper.htm)
or Veritas FirstWatch (http://www.veritas.com/product-info/fw/index.htm) and
we should also mention Marathon's Endurance 4000 (http://www.marathontechnologies.com/).
