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Selecting a reliable NAS solution

When it comes to network attached storage devices, business continuity starts with selecting the right solution.

By Galvin Chang.

With explosive growth of file-based data, more and more businesses, especially smaller ones, entrust their business applications to NAS (network attached storage) systems. NAS systems generally offer support for file and block protocols, enabling users to meet a variety of IT requirements in the office with a single device, including file sharing, data storage, data backup and SAN applications.

Reliability is an important feature of these mission critical systems, since data loss and downtime can potentially lead to revenue loss and can even threaten the survival of the business. When evaluating NAS solutions and examining their reliability, which specifications/features should users particularly consider?

To ensure maximum uptime, ideally NAS systems should come with technologies and features that help users protect data against both physical and logical errors. These technologies and features include the following:

  • RAID technology
  • Hot spares
  • Remote replication
  • Snapshot
  • Protection against silent data corruption
  • Support for remote virus scanning engines.

Protection against physical errors

NAS systems feature multiple disk drives on which data is stored. To ensure that data in a NAS system is not compromised by disk drive failures, RAID protection is a must. RAID technology creates logical storage units from multiple disk drives; data stored in RAID configurations is distributed among different disk drives according to different mirroring and parity schemes that ensure data availability in the event of disk drive failures.

Hot spares – disk drives that are designated to become operational when another disk drive fails – are also important so that a degraded RAID configuration can be quickly restored to fully-protected status without manual intervention.

Besides disk drive failures, NAS systems should also provide adequate protection against system-level errors that occur due to component failures or disasters. In the event of such errors, a reliable NAS system should be able to help users quickly restore service.

An important technology in this regard is remote replication, as it enables data replication from the primary storage site to a remote site that is not affected by events at the primary site. When the primary system fails, users can immediately leverage data kept safe on another system to support business production.

When examining remote replication feature support on NAS systems, users should take a close look at actual technologies offered. Many NAS systems support only asynchronous remote replication for shared folders. An ideal NAS system should be able to support synchronous replication, or data mirroring, between two systems for data stored in both shared folders and block volumes (iSCSI/Fibre Channel). This enables the recovery to be done at zero data loss.

Protection against logical errors

Human errors and virus attacks are the most common logical errors. Snapshot technology in NAS systems allows users to create multiple space-efficient backup copies at minimum time and space requirements that can serve as recovery points. If users accidentally delete or modify files, or if data is affected by virus attacks, these snapshots can be leveraged by users to restore data with only a few clicks.

Scheduling functions are particularly important for snapshot technology. With a schedule feature, users can automate snapshot creation at pre-determined intervals suited to their data environment. Data protection through snapshots is thereby constantly operational, minimizing user configurations.

Another common, but often ignored, logical error is silent data corruption. In the path through which data blocks are transmitted from client computers through the file system to storage media, data can become corrupt due to hardware, software and firmware errors. Most file systems cannot detect such problems, hence the term silent corruption.

According to a widely-cited analysis conducted by CERN, the world’s largest nuclear research facility, every 1TB of files contains three silently corrupted files. To prevent this corruption from leading to greater problems as storage size increases, users should choose a NAS system with an embedded file system that can detect silent data protection and repair data that is affected by silent data corruption.

In this way, users can protect themselves against the unseen effects of silent data corruption and maintain end-to-end data integrity throughout their systems.

The ability to communicate with remote scan engines for virus scanning is another important tool for NAS systems, helping users detect potential viruses. Scanning with NAS systems should offer the flexibility to include or exclude file patterns. Scanning all files could possibly affect the performance of the overall NAS system, and user environments might only need to scan one file pattern to ensure their data integrity.

Author: Galvin Chang is associate director of global product marketing at Infortrend Technology.

•Date: 16th March 2012 • Region: World •Type: Article • Topic: ICT continuity

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