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Hard drives: the deciding factor

Network-attached storage (NAS) systems are growing in popularity among home users – as storage for private data, media servers for music and videos, or a control centre for a smart home, writes Rainer W Kaese, pictured, Senior Manager, HDD Business Development at Toshiba Electronics Europe.

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

The number of digital devices in private households is growing rapidly, and with it the amount of data that needs to be stored. Regardless of whether they are private photos and videos or important documents to be stored, they have one thing in common: they are invaluable to their owners, and loss, for example through a defective notebook or a stolen smartphone, would be very painful. As a result, more and more users are looking for solutions that secure their data treasures centrally 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 comparatively 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 a cloud provider. The alternative, a NAS system, can be a compact and reliable option that is seamlessly integrated into the home network and provides large storage capacity as well as supporting high transmission speeds at any time.

In recent years, NAS systems have evolved from pure data storage and back-up storage to become true all-rounders. They now serve as a central media server for streaming music and videos throughout the household, are used as a control centre for the smart home, and receive images from the surveillance camera at home. Multimedia and communication applications run on many devices, and complete virtual environments can even be set up so that hardly any functional requirements are left unfulfilled. Because the NAS range on the market is huge and includes devices with a wide variety of equipment, an important distinguishing feature is the number of drive bays. For most home users, systems with two bays are sufficient, as they can already provide several terabytes of storage space and offer protection against hard drive failures. Single-bay systems may be cheaper, but they offer no protection against data loss should the hard drive fail. Systems with four or more bays are only worthwhile 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 enclosures 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 deploy the “NAS use” recommended series from HDD manufacturers. These were specially developed for use in network storage applications, and are also on the compatibility lists of the NAS manufacturers, ensuring smooth operation. For “desktop use” classified HDDs may be cheaper, but they are simply not made for 24/7 operation and are usually only designed for an annual workload of 55TB. With several users regularly accessing the storage, internal administration and ongoing control processes of the NAS system, which causes additional read and write activities, these drives quickly reach their load limit. The probability of errors and drive failures increases.

NAS HDDs, on the other hand, 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. The drives can store between 4 and 16TB of data, whereby the larger models are filled with helium and therefore have a slightly lower power consumption than lower-capacity models. The manufacturers offer a three-year guarantee for NAS hard drives – but the HDDs usually run for longer than that without any problems. Experience has shown that often the storage space becomes scarce after this time anyway, so users tend to switch to larger-capacity hard drives at that point.

Redundant array of inexpensive disks (RAID) protects against data loss…

When purchasing HDDs, users need to be aware that the full capacity as shown on the label will not be available for data storage. Disks can be used as individual drives or even combined into a single large drive, but then the NAS does not offer any fail-safety at all. If a disk fails, the data stored on it is lost. It is better to set up the HDDs in a two-bay NAS as RAID 1. The system then saves all data redundantly mirrored on both drives, so that in the event of a hard drive defect, the entire database is still available on the other drive. The defective disk should be replaced as soon as possible. After replacement, the NAS creates a complete mirror of the data again.

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

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

… but is not a backup

A RAID offers protection against data loss due to hard drive failure, but does not replace a backup. To avoid data loss through an event such as ransomware, a fire or burst water pipe, device theft or a defect in the 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. They can be configured in such a way that they will copy specified directories completely or incrementally to an external disk once connected.

It is advisable to familiarise yourself thoroughly with the web-based configuration interface of the device, partly because of the immense range of functions offered by modern NAS systems. Basic functions require some IT knowledge too, so that backups of computers in the home network are reliably stored on the network storage device or by the establishment of remote access from the internet and do not leave any security gaps.

In addition, users should keep an eye on the condition of HDDs so they are not surprised by drive failure. The NAS systems offer, among other things, notification by email, but this must be set up in advance. The status LEDs on the case also indicate problems with the drives, but these may not be seen immediately, because NAS is usually set up out of sight. So a hard drive can fail without the user noticing, but thanks to RAID all data will still be available. However, disaster can strike when the second disk goes. This is the worst cases scenario, and it is when the external backup is worth its weight in gold.


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