It’s the typical Nolan Growth Model. You start out with RAID 5 and tape. Then you graduate to encapsulation with applications and data spread across several servers, but often it is simply with more tape and bigger or multiple tape devices. Finally, it’s time to invest in Direct Attached Storage (DAS) , Network Attached Storage (NAS) , Storage Attached Network (SAN), and Online Backup. The answer of what to implement is different based upon the size of the business.
Small Business customers should consider buying two smaller servers rather than one large one. The servers should be: 1) A Remote Desktop Server (formerly call Terminal Server) for remotely accessing applications without complicated and failure prone VPN and 2) A domain controller/file print server. That old answer of buying monolithic Microsoft SmallBusiness Server and large server to run all those applications and tape or external hard drives is just too costly and maintenace/error prone. The most common mistake small companies make is leaving the tapes on top of the server or in close proximity and not buying new tapes annually. The tapes are usually damaged or wiped from Electro Static Discharge (ESD) or old tapes are past their write life and restore is impossible. External hard drives have the same potential ESD issue and most poeple don’t stop to think that while escaping multiple write limitation, any power surge will damage the external hard drives too. The best recovery answer is online backup. It should not be more than the recurring cost of legacy tape, require proprietary agents on each server, or involve always calling a vendor to restore files or check backup status.
Mid-size and large companies have the challenge of much more data based upon a larger user base. Legacy storage options of DAS and NAS should be avoided. For the unintiated, these appear like good choices as it seems simple and inexpensive. Entry costs are less, but maintenance and growth is time consuming and exorbitant. The problem with direct attached storage is dependence upon the health of one server, space limitations, and difficulty expanding. Problems with the additional RAID card may prevent a server from booting or cause data loss, the 2 TB partition limit means painful data migrations, and moving DAS to another server often requires a different RAID card and hours of installation. With the coming of NAS, direct attached storage is no longer a popular choice.
There is great confusion that NAS and SAN(s) are the same thing. A NAS is a 1995 solution for sharing data from essentially a file server running some limited firmware, rather than a full operating system. It has one way in and out to the network and line of business databases like e-mail and accounting or failover for virtualization cannot utilize a NAS. The RAID partition size limitation still exists and the only answer for growth is backup, buy new, and restore.
Storage Attached Networks (SAN) are the best answer for mid-sized and large storage needs because:
- While entry costs may be higher, on-going cost for maintenance and growth is dramatically less.
- Snapshots provide quick local restore options and built-in replication addresses multi-site and disaster recovery needs.
- Multiple connections to the network allow the storage to be utilized by multiple servers with high performace multi-path I/O performance.
- Data appears local to any attached server allowing line of business applications to have fast access and near unlimited growth.
- Any server with additional network cards can be quickly configured to access SAN data within minutes.
- Volumes may be grown on the fly and new SANs added to existing for pooled shared storage without reconfiguration or full backup and restore.
Finally, no discussion on recovery would be complete without mentioning the trend to simply have a smaller footprint and less to recover. Many organizations are choosing to utilize cloud computing with online accounting, e-mail, and collaboration tools. Instead of simply moving servers to some hosted rack space and still having all the operational burden of maintenance and backup/recovery, cloud computing allows you to enjoy high service level without a physical location dependence or cost of monitoring, maintenance, and backup.