Pros and cons of NAS for SMBs
Network attached storage (NAS) isn't just for the enterprise. Small- and medium-sized businesses (SMB) are also challenged to meet growing file-based data storage requirements. While basic NAS principles are exactly the same regardless of your business size, SMBs have different NAS needs. Typically, SMB NAS systems offer lower storage capacity. For example, the enterprise-class Titan 2500 NAS from BlueArc Corp. scales to 512 TB of storage, while the S300 from StoreVault only scales to 6 TB.
SMBs also sacrifice some of the resiliency and redundancy found in enterprise NAS systems for characteristics such as low-cost and ease-of-use or built-in manageability. Data protection features like snapshots and remote replication are still present in SMB NAS, but typically lack enterprise-class depth and performance.
NAS benefits for SMBs
SMB NAS systems are recognized for three principal benefits; consolidation, deployment simplicity, and ease of management. An SMB might have dozens of individual file server computers scattered throughout the business for order entry, Web serving and other common tasks. A NAS consolidates all of that distributed storage into a single storage system.
An SMB NAS system is also typically simple to deploy, usually requiring little more than a power source and an IP network connection for basic operation. RAID is a common feature for data protection, and some NAS systems now support dual-parity RAID (RAID-6 or RAID-DP) to guard low-cost SATA disk drives against multiple simultaneous disk failures. More disks can easily be installed to add storage capacity, and if the NAS box fills to capacity, a new NAS box can be purchased and connected with equal ease.
Connectivity is also important for the NAS, and SMB systems will typically provide Ethernet network support while offering a supporting direct attached storage (DAS) mode. Some SMB NAS systems currently offer iSCSI support, allowing block-based data storage across an Ethernet-based iSCSI SAN. Systems such as the StoreVault S300 support all three connectivity modes, allowing them to function in a wide range of SMB environments. [See the iSCSI Special Report for more information on iSCSI.]
Management tools allow you to setup and configure the NAS box, manage disk volumes, allocate capacity, assign permissions and perform data protection tasks like snapshot and backup scheduling. Depending on your specific needs, you may also want consider whether the product has remote replication and thin provisioning capabilities. In many cases, a single management tool can support more than one NAS box as more hardware is added into the future. This keeps management tasks simple.
NAS concerns for SMBs
NAS network traffic is always an issue to consider -- particularly in an SMB environment that may have limited resources. Without adequate bandwidth, a network segment hosting the NAS can easily become overloaded and impair performance. If additional bandwidth and resiliency is needed, an SMB may opt for a NAS with multiple Gigabit Ethernet ports that can be aggregated for improved bandwidth. Multiple ports also allow for failover; an essential element of high availability operation.
While RAID can prevent data loss in the event of a disk failure, data must still be reconstructed on the failed disk once it's replaced. A typical disk rebuild can take many hours, limiting access to the RAID group during that time. Some NAS boxes (even in SMB systems) include "rapid rebuild" features that flag impending drive failures and start copying data to a spare drive preemptively. If the disk fails before the copy is complete, only the remaining data needs to be reconstructed.
Don't forget that a NAS can sometimes influence software support. For example, some block-based applications may not support deployment on file-based storage, so be sure to review the applications that you intend to host on NAS and verify that the application vendor will continue to support those applications. Look for opportunities to test a prospective purchase in your own environment before making a purchase commitment.
09 Nov 2007