by November 3, 2010 0 comments



There’s an amazing range of network storage devices that are available today, and it’s quite astonishing to see the variety and the number of features they provide. There’s something for everyone–be it an organization of any size and for any kind of storage requirement. So much so that we actually had to deviate from our original plan of doing a NAS shootout, and do a full-fledged story on different kinds of storage boxes that you can choose from for your network. Presented here is a buying guide to help you choose the right storage box, followed by reviews and comparatives of different kinds of storage boxes you’ll find in the market.

Types of storage devices
Let’s start with an overview of different types of external network storage devices that an organization can choose from. Note that we’ve said external network storage because there’s also a large number of external hard drives available today, which can be directly plugged into a PC over a USB port. Since our story is on network storage, we’ve kept the direct attached storage variety out of this story.
So in the world of network storage, you can choose from the following three types of storage devices:
Desktop NAS: As the name suggests, these are single, rectangular NAS boxes that can be kept next to a desktop or a server, and are portable. There’s a large variety that’s available, right from small boxes that can host up to 2 hard drives to those that can house 7. In terms of functionality, they could be as basic as a small box for taking back-ups to complex boxes that can house a 10 Gbe network card for high-speed file transfers.

Rack-mountable NAS: These are the classical NAS boxes that slide into a rack in your data center. They support all the features of the desktop NAS boxes and more. You could for instance, take the capacity to much higher level, have greater levels of RAID support (like the newer levels 30, 50, 60, etc) and provide higher performance.

IP SAN: At the upper end of the spectrum are the IP SANs, which can be used to cater to storage requirements of enterprise class applications, and support a large number of users. These are modular, thereby allowing you to add multiple storage boxes and controllers, and their costing can be based on the number of features you choose. These largely support block level storage, which results in higher throughputs and I/O operations.

There are multiple vendors offering multiple products in each of the above three types of NAS, making the decision to choose the right one a little complex. So in this story, we’ve reviewed all three kinds of devices to give you an idea of what you can expect from them.

Available features
You can choose network storage devices not only by size, but also by the feature set that they offer. Their prices can vary considerably due to the features they support.

HDD type and interface
There’s a lot more to choosing a storage device than capacity. Once you’ve decided the capacity based on your storage needs, you need to check the types of hard drives supported by the NAS box. Many vendors specify the hard drive that’s compatible with their storage device. The smaller desktop based NAS vendors in fact don’t ship with hard drives at all. You’ll have to buy them separately, so it’s important that you buy the hard drives of the right specification. The storage device is only as good as the drives used for integration. If the drives fail the type of NAS becomes irrelevant. Every vendor certifies certain models of hard disk to be used with their NAS. These should be adhered to so as to keep the warranty in place and also to drive maximum performance out of the NAS box. Also, any NAS is only able to provide about 70 % of the storage plugged in using hard disks because of the RAID configurations. Also, the NAS OS, recovery module etc take up some space also. Hence these calculations need to be kept in mind while purchasing storage. Plus, check whether the storage box is available with SATA or SAS drives. SAS would of course give better throughput than SATA. We’ve tested the Dell IP SAN with both SAS and SATA drives, so you can check out the review to see the performance difference.

Other things to check related to hard drives is whether the storage device supports hot-swapping of hard drives and hot-spare hard drives. Former is important for you to pull out a crashed hard drive while the system is still running, while the latter keeps a separate drive running in standby, which takes over the moment a drive in the RAID array fails. This minimizes system downtime.

Backup
The data you store is only as good as your last good backup. RAID allows timely backup and provides failover capabilities to your stored data. RAID 0, 1,5 are a standard offering. RAID 6 will be a bonus if available as it provides block-level striping with double distributed parity. This basically translates into fault tolerance from two drive failures; array continues to operate with up to two failed drives. RAID, along with Snapshot (Incremental point-in-time copies of stored data) and Replication technologies are therefore common features of any quality network storage device. Some NAS vendors are starting to use the cloud as a back-up platform for a local, physical NAS. The data on the NAS is mirrored to a server in the cloud. These are often known as a “hybrid” backup solutions and it gives the best of both worlds as data is stored in two disparate locations-always ideal for information that you absolutely cannot afford to lose. At the upper end of the spectrum, you also have storage devices with support for RAID 30, 50, and 60.

Data compression
A NAS box which supports data compression will utilize the storage capacity more effectively. Compression means that the same amount of hard disks equate to more storage and thus it means costs savings. A NAS running a compression algorithm is a bit lower on the performance scale point but this difference gets negated by the amount of monetary savings achieved. File screening support helps control which types of files are allowed to be saved on the NAS.

Monitoring and Management
NAS management software allows administrators to deploy, configure, allocate and maintain NAS appliances and gateways within the data center. Remote management and monitoring is desirable for better upkeep and maintenance. A few features a NAS device should therefore have are-Web-based interface, remote desktop connectivity, remote login through telnet or SSH, e-mail and SNMP notifications, disk quota management, file screening and storage reports. Some NAS have an LCD screen which is very effective in basic error reporting and troubleshooting.

Supported file systems, clients, and protocols
Here, you need to check which network protocols are supported by the storage device. Usually, even the smallest and most basic storage devices support protocols like TCP/IP,CIFS/SMB, AFP, NFS, HTTP, HTTPS, FTP,FTP-SSL/TLS, and DHCP Server/Client. If you have a requirement for a different protocol, then you’ll need to check that separately. Likewise, most storage devices can support clients like Windows, Mac, Linux/Unix, and pretty much all popular file systems like Ext3, ZFS, and XFS.

iSCSI support
Even small, basic network storage devices today support iSCSI, the popular storage standard used in IP SANs.You just need to check how many iSCSI targets does the device support, and whether it supports thin provisioning for iSCSI. If so, then you could very well use even simple NAS boxes as an IP SAN.

Connectivity
Most NAS devices out on the market have wired Gigabit Ethernet connectivity. Small, basic storage devices have up to two Gigabit ports for Port Trunking and connection redundancy. This increases network access speed. More vendors are bundling cloud-based services that can provide Internet access to the NAS. However, usefulness of wireless connectivity for a NAS is questionable as essentially servers and computers connected on a network in most organisations use the NAS as local storage. Most organisations do not allow a transfer of data to and from the organisation with the outer world. This feature would add a price to the NAS box and may only be purchased if required. The higher end NAS boxes and IP SANs would provide multiple network ports for multi-pathing support. Some storage devices can be upgraded to support 10 Gbe, which might be useful if you require higher performance from your storage device at a later time.

Security and data protection
A NAS device should easily be able to integrate with your existing directory service for authentication. Some NAS devices allow you to install anti-virus software directly on them, while others let you do remote scanning. Access Control Lists are used to allow file and share-level access for authenticated users and groups to files and folders stored on the NAS.

A network storage device should audit and log most tasks done like log on, log off, security modification, password changes, user creation, etc.Many devices support file encryption. Others also offer a variety of security controls to protect the NAS from intruders with firewall-like access protection.

Other data protection features to check for include various types of snapshotting (number of snapshots supported, snapshot assisted replication for DR, snapshot creation and roll back speed, etc). Plus, check what sort of remote replication support it has for DR. Check for direct UPS support, redundant power supply, etc.

Other features
You can also look for a redundant power supply in the NAS. Some devices have built in Web servers, BitTorrent clients, iTunes server and even Telnet. Some can do double duty as a MySQL or FTP server. Many can not only stream multimedia, but can work with IP-based surveillance cameras. Several NAS have features that are designed to save on power consumption. These devices can be shut down, placed in hibernation or started according to a preset schedule. Many of these also have system monitoring tools that will report on the system’s temperature and CPU voltage. Some have Smart Utility fans which will cool the hard disks drives down automatically to prevent overheating.

Other features to check include load balancing and failover support:

Performance
Like PCs, storage devices units also have memory and processors. With faster processors and higher memory, you get better performance. If your storage device will be handling a lot of I/O operations then its advisable to buy one that has a nimble processor and maximum memory. Ensure the number of users wishing to access the NAS device will be supported and the current installed network backbone will not suffer degradation in performance as a result. In case of a NAS, the existing network infrastructure should not need any change or modification just to incorporate it into the network. An IP SAN would anyways require its own separate network.

Expandability
Adding capacity, memory and a change of processor are risk based upgrades that may nullify manufacturer warranty, if not performed by an authorized reseller. Add a secondary unit that allows failover and/or is stackable.This basically adds another layer of protection for your data. That way you are adding a tremendous capacity through extra storage, increasing performance that may equate to having a dual processor and memory as the processor and memory units are basically utilized to fetch indexed storage. Having more units provides more processing power to your system.

Price and warranty
Warranty is paramount if a zero tolerance for downtime is a mandatory requirement. Vendor support during any hardware or software failure is of utmost important as your network can not afford a large downtime. Last but not the least is the price you pay. There’s a huge variation in the prices depending upon the features built into the NAS. So the first thing to do would be to get a detailed pricing structure for the storage device you’re planning to buy. Next, check whether software upgrades would command additional payments. Some vendors offer free software upgrades, which also means that any additional features that might get added to the software are given to the customer free of cost. Some vendors charge extra for it, so you must ensure you get this cleared from your vendor before buying.

Related Articles:

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Dell EqualLogic PS Series iSCSI Storage Array

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