SMBs have been adopting network-attached storage (NAS) devices for many years because NAS devices are relatively...
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inexpensive when compared to storage area networks (SANs). Many feature almost automatic installation and setup, and they promise to provide a quick fix to the growing data storage, backup and recovery needs of many businesses. Unfortunately, the wrong network-attached storage selection can result in unexpected performance problems. In this article, we'll look at many of the common NAS performance issues to ensure SMBs are getting adequate NAS performance from current or future NAS investments.
One of the most obvious causes of performance issues is an SMB whose networking infrastructure isn't fast enough to take full advantage of the network-attached storage equipment. NAS devices are equipped with at least one 1 GB Ethernet NIC. In many cases, network-attached storage devices may have a second, or even a third, 1 GB NIC. The infrastructure connecting to the NAS should support Gigabit Ethernet. In some cases, however, a NAS device is installed onto a 10/100 network, equipped with 100 MB switches and routers.
To get full performance, upgrading your network infrastructure to 1 GB, and upgrading your cable to CAT5e or CAT6 will help to provide the bandwidth necessary to take full advantage of the network speeds on the NAS device. Furthermore, not just the network backbone should be addressed, but you should make sure that "1 GB is on every new desktop and notebook computer," said Mark Tanguay, general manager for network storage products at Iomega, an EMC Corp. company.
Although it should be obvious, the use of WiFi may provide performance disappointments for users. Wireless connections, at their best, may be adequate for moving small files, but these connections slow down when sending or receiving larger files. For computers that are used for moving large amounts of data -- even occasionally -- direct connection to the company's Ethernet is required. Another related issue is the use of Netbooks, which don't provide enough processing power to sustain high-speed data transfers. Altough Netbooks are relatively inexpensive and easily portable, their performance may make NAS performance seem slow.
Depending on the network-attached storage device, those with two or more NICs can provide one or more benefits. A second NIC can be used for redundancy, and is attached to another subnet. Should one network connection fail, the secondary Ethernet connection can handle the rerouted traffic. Other devices use a second NIC for NIC teaming, which doubles the performance of a single NIC. In both cases, either a secondary network, or a switch that supports NIC teaming will be most effective for the additional NICs.
For companies that use their network-attached storage devices for backing up servers and workstations, scheduling the backup tasks is important. If many users attempt to perform backups at the same time, the extra load on the NAS could result in performance problems.
Plan ahead when adding a NAS device
Planning the level of network-attached storage device your company needs can also help avoid performance and installation problems in the future. For example, a small company purchasing a low-level network-attached storage device may find it very easy to install and set up. Configuration in an office may involve going to each computer and mapping the NAS device to each computer.
"When you add a new network-attached storage device, you may have to go to everybody's computer and map a new drive," said Kevin Schoonover, director of engineering in the Arrow ECS Storage Group at Arrow Electronics Inc. Finding an expandable network-attached storage system that would allow the IT department to add drives as needed, without requiring changes in volume mapping, could save the trouble of mapping new drives that smaller, less expandable NAS devices require.
In an extreme scenario, with many two or four drive network-attached storage systems attached, it is conceivable that an SMB may run out of letters of the alphabet for mapping the drives. Sharing a single NIC between a dozen or more NAS drives could result in increased network traffic when compared to other NAS systems that support the addition of drives without necessary volume remapping.
In addition, balancing RAID levels to an SMB's finances and performance needs is an important factor. For pure performance, RAID 1 with mirrored drives may provide the highest level of data security; however, you'll need twice the required capacity. With RAID 5, each drive is being sequentially read from, meaning its variants provide a high read performance. But writes are slower because of the processing required for striping across the drive array.
The capabilities of the network-attached storage device, though often not included in the product specifications, are also worth checking. "The amount of memory on a NAS can help [improve performance], especially if a network-attached storage box can support multiple drives. Memory has only so much capacity to cache the drives. Having larger memory to cache a larger number of files can cache the [reads and writes] quicker. The combination of spindles and memory can provide better performance," said Karthik Angamuthu, product marketing manager for Power Vault Disk Storage at Dell.
Virtual LANS and NAS
Brad Sakai, product management at the small business unit at Cisco Systems Inc., suggests the use of virtual LANS (VLANs) to help shape the traffic going to the network-attached storage. A VLAN runs as a process separate from the current network operating system. It can establish a secondary network, working through a second network port on the NAS. The network traffic generated on a VLAN is independent of the traffic traveling over the basic network. Sakai suggests backing up files on one VLAN, and using a separate network for other traffic. Isolating the types of traffic to separate networks can help improve performance.
For SMBs doing large amounts of work with graphics, using computers with PCI-Express can also help improve performance. These improvements result from having the high speed graphic processor working on the graphics as they're received. A PCI-E video card, installed on machines that are doing graphic manipulations -- whether client or server -- can accelerate the processing of the graphic data, thus reducing the amount of delays waiting for transfer of data between the computer and the NAS.
Data deduplication and network-attached storage
Finally, the issue of data deduplication should be considered. Data deduplication deletes redundant data, replacing it with a pointer to the original file. Dedupe is a relatively recent enterprise data storage development that improves storage capacity while also improving performance (because less data has to be searched in order to find the desired files). Data deduplication significantly reduces the amount of data stored on the NAS -- sometimes by as much as 70% or 80% by replacing duplicate files on the NAS with tags that refer to the original file. This significant reduction in the amount of data actually stored on the NAS reduces the actual amount of data that the NAS must access. Less searching and less head movement results in faster access to data.
"I'm seeing storage vendors who do data deduplication on the device itself," Schoonover said. This feature can help to reduce or resolve performance issues before they become problems.
Careful planning and purchasing of network-attached storage devices, assessing current needs and future growth expectations, and choosing the features and expandability for your company can help to minimize performance issues of your NAS. Coupled with the need to maintain your infrastructure, and the network capabilities of servers and workstations can help to avoid performance issues and make NAS an important part of your company's storage spectrum.
About this author: Mark Brownstein is a technology journalist with experience editing computer storage publications. He also runs his own networks, is owner and operator of a test lab, has written books about computing topics, and is an MCSA. He regularly tests and evaluates new products and technologies, and constantly seeks freelance opportunities. When he's not up to his elbows in computer stuff, he lives in Northridge.