NAS (Network Attached Storage) is a complex stand-alone device outfitted with everything necessary for not barely data storing but also sharing and, for some models, streaming. Due to comfort and possibilities NASes bring into this world, they have become popular among different user groups from home users through small office and up to corporate clients.
Generally, the purposes the NAS devices are used for can divided into three categories:
- Data backup. You’ll hardly find a better solution than NAS to maintain your backup schedule. This device provides additional storage for your archival purposes. In addition, unlike an outsourced subscribed cloud, the NAS is located at your place, therefore, is under your own control.
- Data sharing. Whether at home or in an office, NAS servers are capable of communicating with other devices. Via the local area network (LAN), a small file server provides all computer devices attached to this LAN with access to its files. Besides, one can reach the device from any point of the world via the Internet using its web-browser based user interface.
- Data streaming. NAS is not merely a storage it is a smart storage. It relies on its own operating system ensuring support for such local media services as iTunes or DLNA. As a result, the NAS becomes a direct source for playing music and video or showing pictures. NAS can also be used for Internet of Things (IoT) components or control system in your house.
As an independent device, a NAS storage is completed with its own CPU, memory and hard drive components. NAS devices can include one or more disks, which can be extendable depending on the model. Several disks in NAS storages normally integrate into one RAID system. There exists a great deal of different RAID configurations with its particular data organization scheme each. Depending on what you configure, you can organize a good balance between storage performance, overall capacity and device reliability.
NAS devices offered at the technologies market these days can be arranged into three major user groups:
- Users with advanced technical skills. An example of a NAS developed for these users may be Buffalo, a file server based on a technical interface.
- Users with average technical skills. Typical retailers for this user group include QNAP and Synology.
- Users without technical skills. Such retailer as Drobo offers users a complete solution without revealing them the guts.
NAS is exposed to data loss common for all data storage devices including logical failures of an operating system, effects of viruses and malicious software as well as accidental file deletion. At the same time, NAS storages feature their particular data loss situations like operator errors during RAID re-configuration or incorrect adding of new disks into the NAS box, NAS software failures or faulty updates etc.
Let’s take a closer look at possible logical damages of a NAS storage.
Depending on the vendor, NAS storages may or may not provide the user with options to select and change its configuration. Professional models, such as Buffalo, give an extensive set of options, while the Drobo is unlikely to let you in. Let’s assume you have such choice.
There are several ways of data organization on a NAS device. First, the storage may merely consist of the only hard drive or several drives not organized into one system. From this perspective, it is only slightly different from a computer in terms that it doesn’t have a display, a keyboard and a mouse.
Second, NAS drives can be combined into a RAID system. A variety of RAID configurations allows creating either redundant or non-redundant NAS storage. RAID configurations of RAID 0 and JBOD are non-redundant. Their data allocation schemas increase overall storage performance but do not provide for a higher level of data safety because they do not use data duplication (mirroring) or parity – a special checksum to calculate missing pieces of information in case of loss or unreadability. A redundant NAS will be a more reliable solution due to parity or duplication appliance. At the same time, you may lose some percentage of storage space dedicated for parity or data copying.
Certainly, it’s absolutely up to you if you want to get maximum space and create a non-redundant storage or you would like to be less risky and invest in reliability on account of a redundant configuration. What data recovery experts claim in both cases, is to be attentive to your storage. In case of linear or non-redundant NAS, be aware that its components are less than eternal. Additionally, some retailers may supply the box with low-quality disks inside. Hard drive resource may also be up as the time flows. As for redundant NAS be sure to react timely to its messages and never ignore the necessity to replace a failing NAS drive.
If the situation requires turning to a NAS support team, draw their attention to the fact that your data is an important thing and call for a backup.
Similar to other devices NAS is also vulnerable to voltage fluctuations and power problems. Their outcomes may damage the system drastically resulting in loss or injury of RAID metadata. The most apparent consequences of the metadata loss include:
- Volume failure. If you cannot find the shared folder in a web interface of the storage, this may be caused by volume failure.
- Degraded mode. If one or several disks are off the system, NAS may switch to a degraded mode.
- Partition table loss. If RAID fails to boot at all, it can mean that RAID metadata damage might have resulted in loss of the partition table.
In any of the above-mentioned events, you will need to take the disks out from the NAS box, connect them to a computer one by one and start Recovery Explorer to retrieve your data. In order to bring the box itself back to a working state, you’ll have to replace the drives if they have broken down, and only then reconfigure the storage with a new RAID via the web interface. In case of a boot failure, you’ll need to return the storage to factory default settings.
Remember proceeding to manipulations over the NAS box only after having recovered all necessary files.
Users having faced the problem of breakdown or emergency condition of the NAS storage would usually turn to a support team of the device retailer. One of the problem resolving methods may involve firmware upgrade. This is a good chance to make the storage work again, nevertheless, a possible reason for complete loss of the data is inside the device. The upgrades can bring serious modifications inconsistent with old data storing methods. For the purposes of necessity to bring the device back to a working state, the system may decide to reset NAS firmware trying to set the disk to nil and format the drive in order to create a new file system.
Please be sure not to start any manipulations targeted at changing device firmware or storage configuration prior to copying out vital files. If the storage does not let your data be copied, please, turn to a special data recovery center first.
Storage capacity expansion
Life expands, data expands, the necessity to expand storage space increases. It’s not that the device upgrade is a bad thing. After all, you improve functional possibilities of your box. The thing is that you should do it with an extreme care.
Extension of the storage capacity overloads disks in the very process of expansion. NAS storage switches to a RAID rebuild mode what gives an additional working load. Besides, the RAID rebuild is quite a lengthy procedure that requires assurance of stable work conditions. Possible power cutoffs or voltage fluctuations may bring along fatal NAS failures. It’s recommended to power the device on via UPS and to try avoiding data read from the storage for the rebuild period.
Alteration of NAS configuration
Users may want to change storage configuration for a number of reasons, including building RAID, storage capacity increase, forming a redundant RAID configuration etc.
On the other hand, not every NAS retailer allows altering the NAS scheme on the fly and without endangering your data. Those who don’t (Buffalo, for example), cannot guarantee that your data remains after the configuration change. Even in case of retailers claiming safe NAS modifications (like Drobo) the other side is that you can never predict what is going to happen there inside.
The process of configuration change may pose a serious danger, as it does all operations over a live system. If for some reason more than one disk in RAID 5 and more than two disks in RAID 6 break down during the rebuild process, volume becomes inaccessible and the data cannot be read out any more.
Another risk factor are power cutoffs before the update is over which can happen merely by inadvertence – you may catch in the cord while passing by. As a result, RAID controller may fail, the whole procedure crashes, storage volume becomes inaccessible, and in combination with a complex RAID configuration, you face firmware problems. The more severe the outcome is, the less data recovery centers will cope with such data loss situation.
Please note that NAS rebuild is carried out in real time over the switched on storage. Try to avoid using the device at that moment. Finally, the less overloaded it is, the sooner the process is up giving less time for breakdowns.
Yet, how can one ensure secure conditions for work with NAS?
Despite the fact that NAS is advertised as a safe data storage solution, you should remember that it can still break down at both physical and logical level. Non-redundant configurations require closer attention to the failing drives. Redundant configurations need your attention to the warnings about the storage space and immediate actions on a failed disk replacement.
Overall, at the very first step of creating storage configuration remember that you will use storage capacity on the account of storage safety. Data recovery specialists from Sys Dev Laboratories consider RAID 5 and RAID 6 configurations the most reliable and promising from the recovery perspective.
What works best is the rule: Think before you do and…establish a distinct backup schedule.