Hard disks: the deciding factor

Network Attached Storage (NAS) systems are becoming increasingly popular among home users — as private data storage, media servers for music and videos, or a control center for a smart home, writes Rainer W Kaese, pictured, Senior Director, HDD Business Development at Toshiba Electronics Europe.

They provide an alternative to cloud storage for home users who want to keep all the data within their home environment. However, the choice of systems and storage drives these days is huge. Questions arise, such as which device is suitable – and why should it be with private NAS hard drives?

The number of digital devices in private homes is growing rapidly, and with it the amount of data that must be stored. Regardless of whether they are private photos and videos or important documents that need to be stored, they have one common denominator: they are invaluable to their owners, and losing, for example through a faulty laptop or stolen smartphone, would be extremely painful. As a result, more and more users are looking for solutions that centrally secure their data treasures while also allowing other devices or family members to access them when needed.

Cloud services are often chosen as central storage locations for reasons of simplicity, but they offer relatively little free storage space, and data transfer can take a long time depending on the available Internet connection. In addition, not every user likes to entrust private data to the cloud service provider. An alternative, a NAS system, can be a compact and reliable option that integrates seamlessly into a home network and provides large storage capacity as well as support for high transfer speeds at any time.

In recent years, NAS systems have evolved from pure data storage and backup storage to become comprehensive systems. It now acts as a central media server to stream music and videos throughout the home, is used as a control center for the smart home, and receives images from the home’s security camera. Multimedia and communications applications run on many devices, and even entire virtual environments can be set up so that no functional requirements are left unmet. Since the range of NAS on the market is huge and includes devices with a variety of equipment, an important distinguishing feature is the number of drive slots. For most home users, two-slot systems are sufficient, as they can already provide several terabytes of storage space and provide protection against hard drive failures. Single-chamber systems may be cheaper, but they do not provide any protection against data loss in the event of a hard drive failure. Systems with four or more slots are worthwhile only if the user intends to store very large amounts of data and has high performance requirements – for example, video enthusiasts.

Most NAS systems are sold as empty attachments that the user will need to equip with hard disk drives (HDDs). In principle, the devices work with almost all SATA drives, but users should publish the recommended “Use NAS” series from hard disk manufacturers. Developed specifically for use in network storage applications, it is also included in NAS manufacturers’ compatibility lists, ensuring smooth operation. For “desktop use,” rated hard drives may be cheaper, but they simply aren’t designed for 24/7/365 work, and are usually only designed for 55TB annual workloads. With many users regularly accessing the NAS system’s ongoing storage, internal management, and control processes, causing additional read and write activities, these drives quickly reach their load limit. The probability of errors and leadership failures increases.

On the other hand, NAS HDDs can handle a workload of 180TB per year. They also have vibration sensors and control mechanisms that prevent the rotational vibrations of several hard drives in one housing from amplifying each other and impairing performance. Drives can store between 4 and 16 TB of data, the larger models are filled with helium and therefore consume slightly less than the lower capacity models. Manufacturers offer a three-year warranty for NAS hard drives – but hard drives usually run longer than that without any problems. Experience has shown that storage space often becomes scarce after this time anyway, so users tend to switch to larger capacity hard drives at that point.

Inexpensive redundant disk array (RAID) protects against data loss…

When purchasing hard drives, users should be aware that the full capacity as indicated on the label will not be available for data storage. Disks can be used as individual drives or even combined into one large drive, but then the NAS offers absolutely no failure security. If the disk fails, the data stored on it is lost. It is best to set up hard drives in a dual-slot NAS such as RAID 1. Then the system saves all the data that was repeatedly copied to both drives, so that in the event of a defect in the hard drive, the entire database remains available on the other pieces. The defective disc must be replaced as soon as possible. After the replacement, the NAS creates a complete mirror of the data again.

With RAID 1, the NAS storage capacity corresponds to the capacity of the smallest hard drive, i.e. two identical drives, half of the total combined capacity.

NAS systems with four or more slots support higher RAID levels where a greater percentage of the total capacity can be used. These also achieve higher performance through intelligent data distribution across individual drives. However, in typical home networks, this is rarely noticed because the transmission speed is limited by Gigabit Ethernet. Of course, there are also NAS systems with faster interfaces or two Gigabit LAN ports, which can be interconnected via link aggregation. However, this investment is only worthwhile if the switch and other devices in the home network support higher data rates or port interconnection.

…but it’s not a backup

RAID provides protection against data loss due to hard drive failure, but it does not replace a backup. To avoid data loss through an event such as ransomware, a fire, a water pipe burst, a device theft or a defect in a NAS, users should regularly save their data to another storage device and keep it off-site – for example with relatives, or in the office. The easiest way to do this is with a USB hard disk, as all NAS systems have an interface for USB 3.0 or faster. It can be configured in such a way that it copies selected directories completely or incrementally to an external disk as soon as it is connected.

It is advisable to get familiar with the web-based configuration interface of the device, in part due to the huge range of functions that modern NAS systems offer. Basic functions require some knowledge of IT as well, so that the backups of computers in the home network are reliably stored on the network storage device or by creating remote access from the Internet and leave no security holes.

In addition, users should monitor the status of their hard drives so that they are not surprised by a drive failure. NAS systems provide, among other things, notification via email, but this must be set up in advance. The status LEDs on the case also indicate problems with the drives, but they may not be seen right away, because the NAS is usually set up out of sight. So the hard drive can fail without the user noticing, but thanks to RAID all data will still be available. However, disaster can occur when the second disc goes away. This is the worst case scenario when an external backup is worth its weight in gold.

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