Network-attached storage technology allows storage to be added on the LAN simply by attaching dedicated devices through a standard Ethernet connection. It's easy to add single NAS devices, but each "NAS box" requires a certain amount of management. As more NAS devices are added to the network, their management demands are cumulative, eventually imposing a serious level of management overhead for storage managers and IT staff. Organizations that plan to deploy NAS technology should make ample provisions for common management strategies.
Network-attached storage backups
Backup windows, recovery point objectives and recovery time objectives are all shrinking. Business can no longer afford hours of disruptive backup time, nor the 12-24 hours (or longer) needed to restore from a disaster. Disk storage offers attractive cost and fast performance, so disk-based storage systems are increasingly being pressed into service for backup tasks. NAS systems are particularly interesting as backup targets because of their plug-and-play simplicity , and file-based backups are a natural fit for common NAS platforms.
NAS disks typically operate behind a filer head that interoperates with common file systems like NFS or CIFS. Although any NAS box can be used for backups, some NAS appliances are dedicated to backup tasks. One is the NearStore FAS3040 system from Network Appliance Inc., designed for nearline storage from 8 TB to 336 TB using inexpensive SATA disks. When employing a NAS system as a backup target, be sure your backup software supports the Network Data Management Protocol (NDMP)
. NAS clustering and availability
One way to reduce the number of individual NAS boxes is to deploy fewer but larger ones. While major NAS vendors such as NetApp have embraced this strategy in its FAS3000 family, some users are loath to adopt such a monolithic approach. Instead, they pool NAS capacity through clustering.
Clustered NAS systems work cooperatively and appear as a single NAS. Each clustered element can share the data load, and one box in the cluster can step in when another box fails, creating high storage availability. OnStor Inc. provides a clustered Pantera NAS appliance and NAS gateway designed to interconnect Windows, Linux and Unix client systems with up to 40 petabytes of storage capacity.
Software plays an important role in clustering. Global namespace support is essential to handle large numbers of file objects spread across multiple storage systems. Management tools should support the full cluster size with a minimum of configuration or overhead labor. Evaluate these software tools to ensure you're getting the management, provisioning, data migration and storage utilization features you need. Snapshot and replication features can also help storage managers protect valuable company data.
Another way to deal with a proliferation of NAS devices is through virtualization. Just as virtualization technologies can organize server storage and treat disparate hard disks as a single pool of storage, virtualization technologies can also be applied to NAS devices. Dedicated NAS virtualization appliances are typically installed between NAS boxes and the network, organizing multiple NAS boxes into a single, uniformly managed pool of NAS storage.
NAS appliances aren't just for show. Many of these appliances can balance storage traffic between NAS boxes, thereby optimizing I/O performance. Appliances can also change storage volume sizes and move volumes between NAS devices on the fly without any impact on storage operations. NAS virtualization appliances include the F5 Acopia ARX Series, virtual servers from BlueArc Corp., the V3000 and V6000 appliances from NetApp, and the Rainfinity global file virtualization appliance from EMC Corp.
Virtualization techniques generally use file management software to direct files to the appropriate NAS device. StorageX is Brocade's virtual file manager product. Companies like Crosswalk Inc. provide even more comprehensive management. For example, the Crosswalk NAS monitoring and reporting module provides monitoring and reporting of multiple distributed NAS systems, along with data classification, storage resource management and performance analysis/diagnostic features.