Single controller, dual controller

Entry level storage systems comes with single controller. If one controller fails there is no alternate path for the data. Dual controller systems give full redundancy. With good management software dual controller systems give load balancing and path failover features and ensure high availability. iSCSI, Fiber channel interface iSCSI interfaces offers lowest cost with 1 GBp/s interface with host systems. With host systems there is distance limitation 20 m.Fiber channel interface gives maximum data transfer of 4GB/s swith the host systems. With fiber channel interface you can also eliminate the distance barrier with the host servers.

Scalability 

Your systems should be scalable to your growing requirements. You can choose different models which can host 12 HDD, 24, 40, 60, 90, 200 etc. The number of host servers can be connected to the system is another criterion of expandability.

Backup and restore

For backup and restore tapes are being used as offline storage. As said earlier since these systems are slow you need to compromise on the recovery time. Now the hard disks are getting cheaper and the business moving to have online systems with NAS and SAN. Files servers, data base servers, application servers and operating system images are being backed up. You need appropriate software and connectors/plug-in/API for backing up different applications and different database systems. Modern IT infrastructure is heavily relies on virtualization. You need appropriate management systems to back up and restore virtual machines.

SATA, SAS, FC

You can put SATA in the entry level systems. This gives the lowest cost per GB. Even the entry level storage systems provide SAS connectivity. This would be ideal on cost performance ratio. Fiber channel harddisks give the maximum through put and are Suitable for high performance systems.

Replication

Remote replication technology generally more associated with disaster recovery. You need to simplify the management of replication process and ensure the integration with major software vendors such as Microsoft, oracle etc;

De duplication

There is deduplication software like Avamar identifies the redundant data and minimize the backup data. Deduplication technology reduces the bandwidth requirement when backing up from remote offices. This process also the reduces the backup time.

Archiving

For archiving tape drives are being used as offline storage. Tape systems are slower but cheaper. Since offline, tape media can easily be transported. For online systems CAS-content addressable systems are used. CAS systems are mainly used where you have non changing data .These systems mainly adhere to the compliance standards. Backing up mails is one example. Storing and managing legal documents and compliance standards is another example.