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In businesses and households alike, NAS storage systems are a popular solution due to the wide variety of devices and hard drives available, where most people can find their preferred option. Whether the main criterion is price, high capacity, or expected reliability. In addition to NAS and drives, it is advisable to also consider potential power outages and purchase a UPS, or uninterruptible power supply. And if you want to optimally combine NAS and UPS, find a suitable UPS on the manufacturer's website that will communicate with your NAS in case of a power outage and turn off the NAS when the battery capacity starts to wane.

RAID Repair after Disk Failure

If we have a RAID configuration in our NAS that is resistant to the failure of one or more disks, it is essential to immediately replace the faulty disk with a new one. We have encountered cases where the client, or even their IT administrator, ignored warning signals. The data was still available at that moment, and everything seemed to be functioning normally. For example, RAID 1 or RAID 5 are resistant to the failure of a single disk. Disks for NAS are usually purchased at the same time and are the same model, so they are likely from the same batch. Therefore, a situation may arise where, due to some manufacturing defect, multiple disks fail shortly after one another. In this case, a simple replacement of a single failed disk can turn into a complicated data recovery from the disk array. So, do not ignore the warning signals from your NAS.

Data Recovery / RAID Data Rescue

RAID can fail, whether due to simultaneous failure of multiple disks, a fault in the NAS itself, file system errors, external factors that the user did not anticipate, or incorrect intervention by the operator. The chance of such a scenario is, of course, dramatically lower than if you entrust valuable data to a single ordinary disk. However, it can happen, and in such a case, a helpless user should avoid attempts that could worsen the situation. Contact us for a free consultation on the problem.

Data recovery from RAID is usually complicated, and it is not advisable to work directly with disks containing valuable data. Some of them may be defective. The first step is to create a binary copy of all RAID disks. This operation can be technologically demanding (especially in case of failure of one or more disks), time-consuming, and capacity-intensive. For example, if we have a RAID disk array consisting of 4 x 6 TB disks, we will need 24 TB of free space to create binary copies. Then it is possible to perform the necessary operations to assemble the RAID and recover data in read-only mode, or with write simulation to a separate layer. However, do you also know other parameters of the disk array and have sufficient experience and equipment?

If the error occurred only on the NAS side and all disks are in good condition, in some cases it is possible to restore the disk array using a new NAS of the same brand. However, the manufacturer bears no responsibility for any errors. The responsibility is always on the user.

The aim here was not to provide a guide on how to recover data from RAID but to point out the need to follow the correct procedure in case of RAID disk array failure, or Network Attached Storage (NAS). With your inquiry on a specific problem, we will be happy to advise you.

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Hard Drives (HDD) Suitable for Use in NAS

In a network storage device, multiple hard drives usually work together and should be able to operate 24/7. Therefore, it is more than appropriate to use disks in NAS that the manufacturer has designed for such use. Factors to consider include higher vibrations, different operating temperatures, or their progression, and expected higher operating hours than in a typical desktop computer. Disks intended for NAS have a more robust construction, a longer expected lifespan, and are simply suitable for such use.

Whether to use the same brand and identical model or a combination of multiple brands in NAS is perhaps a topic for a longer discussion. Disks should certainly have the same parameters, all must be intended for use in NAS, and under no circumstances should conventional recording (CMR) and shingled magnetic recording (SMR) disks be combined. We wrote about the suitability of CMR and SMR disks in the article SMR - The Hidden Function of Some WD, Seagate, and Toshiba Disks. Is it Necessary to Worry About It?. In general, it is probably more suitable to use conventional recording disks, i.e., CMR, in NAS.

Which disks to use in NAS? Among the largest manufacturers, Western Digital RED or GOLD, Seagate IronWolf or EXOS, or Toshiba N300 are available. Even among them, you should choose based on the type of use, expected lifespan, etc. If you are unsure about your choice, do not hesitate to contact us.

Appropriate RAID Configuration. Disk Failure Resilience and Speed

There are many possible RAID configurations. In addition to the basic division into RAID 0, 1, 5, 6, 10, 01… other parameters also need to be set. However, modern NAS devices take care of this task to a large extent by themselves, so for the purposes of this article, let's assume that if a user wants to set some advanced NAS parameters themselves, they already have enough experience and know what they are doing.

In the vast majority of cases, the NAS user will want the disk array to be resistant to the failure of at least one disk. The most common configuration for a small two-disk NAS will then be RAID 1 - mirroring of two disks. Each disk contains identical data. For NAS with more positions, we will likely choose RAID 5, which requires at least 3 disks and is resistant to the failure of one disk. RAID 6 is similar, but up to 2 disks can fail, and it consists of at least 4 disks. For example, Synology NAS, in addition to the mentioned configurations, also offers SHR - Synology Hybrid Raid. It is an automated RAID management system from the mentioned Synology company. It has its advantages and disadvantages, but if you are a beginner and do not want to pay too much attention to the configuration of Synology NAS, then SHR will be the right choice.

UPS Backup Power Source - A Sensible Choice

A NAS is essentially a small computer, and especially if traditional hard drives (HDD) are used in the NAS, a power outage is never good for a running NAS. All disks will unexpectedly shut down, which can lead to the loss of some data or, in a worse case, the failure of a disk or the entire disk array. It is worth paying a little extra to get a backup power source - UPS for the NAS. There are a variety of cheaper and more expensive UPS options available in the market. Ideally, choose a UPS recommended by the manufacturer of the NAS. The NAS should be able to communicate with the UPS via a USB cable and give it a shutdown command if the backup battery capacity is running low.

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Checking NAS and Disk Functionality

Hard drives can occasionally start to malfunction or fail completely. The NAS itself also requires occasional inspection, cleaning, and updating… It is a good idea to set up error reporting in the NAS. This way, you can promptly detect a malfunctioning hard drive and immediately replace it with a new one. Visual inspection of the NAS can also provide information, and in case of a failing hard drive, the NAS will typically alert you with a light or sound signal. After logging into the NAS administration, it is also possible to check for any errors or non-standard conditions.

Updating the NAS operating system can bring new features, resolve deficiencies in the previous version, or patch security vulnerabilities. These are all expected benefits. However, sometimes an update may not be fully tested and fine-tuned. If there is no critical security issue in the NAS operating system and the update is not essential, it is advisable to wait for some time and read about other people's experiences online.

Both RAID and NAS can fail

RAID is not a backup, which many people mistakenly believe. If RAID fails or the NAS stops working and you do not have a backup of your data, you will find out the hard way. Data recovery is usually possible, but a lot depends on the user's correct approach. More information on this topic can be found at the beginning of this article - Data Recovery / RAID Data Rescue