IT Architecture - Storage Basics-1

IT Architecture

IT architecture describes the way servers and hosts accessing the storage. Storage consists of various disks which are shared between the hosts.

It is deployed in the environment where there is a requirement of shared memory between the server e.g shared drives. Storage disks are appeared as the directly attached disk to the servers.

There are below two types of IT architecture.

1.Server-Centric IT Architecture:-

It is a traditional or legacy design where hosts are accessing storage disk via dedicated servers. They cannot access the storage directly. 

Servers are connected to hosts via traditional LAN and to storage disk via SCSI cables. There is no dedicated storage network for the Hosts

Advantages:-

1. Easy Deployment: - Deployment of server centric IT architecture is simple and easy . It is still in use for small deployments.

2. Less Expensive:- There is no involvement of expensive storage devices and dedicated storage network which saves a lot of expensive. It not only saves the device expense but also the expense on the skill required to deploy and maintain the infrastructure.

Disadvantage:-

1. Less Scalable :- 

•   Each server can support limited number of I/O Cards which restrict the scalable
•   Since SCSI cable has the limitation of 25m length, servers and disk cannot be connected beyond 25m.
•    Storage and servers are deployed locally as per the requirement since it cannot be 25m apart.

2. Less Reliable: - There are usually one or two upfront servers which gives very limited fault tolerance to the design. Failure of server can lead to major outage.

3. Less Efficient: - Suppose Storage disk, i.e. storage-2, connected to server-3 is full, now there is no way for Server-3 to get extra storage even if large amount of space is available on storage-1.

4. Security issues: - Since the deployment is scattered, there are always risk of unauthorized access.

5. Environment issues: - Due to the scattered behavior, it is very difficult of maintain the temperature in the various data closest.

6. Complex design:- It is not suitable for large deployment as it will lead to very complex design.

2.Storage-Centric IT Architecture:-  

IT architecture with storage dedicated network is called storage centric design. All the SCSI cables present in legacy designs are replaced by separated storage network.  Small disk are also replaced by big storage boxes called disk subsystems.

Like server centric design it also has its own advantages and disadvantages which are discussed below.

Advantages:-

1. Efficient: - Now one server can use whatever storage it wants.

2. Scalability- Since there is separate storage network and large storage devices, it is capable of handling large number of hosts. It is highly recommended for large data centers where the number of servers and hosts are high.

3. Secure: - As the storage is located centrally, it is very easy to restrict the unauthorized access.

4.  Environment issues: - Because of less number of data center, it is quite simple to maintain the temperature and monitor other environment parameters.

5.  Simple design:- Storage centric design are quite easy to understand, deploy and maintain.

Disadvantage:-

1. Expensive: - Requirement of separated storage network adds extra cost to the deployment. It also requires storage specific skills to deploy and manage the infrastructure.

2. Suitable for large and medium deployment only.