Network Attached Storages (NAS) are devices specially designed for storing and sharing files over a local network. These storages work as small file servers and they don't perform any functions like e-mail, authentication or file management.
Prepare for recovery
A NAS devices consists of a control board which provides network access to data and from one to several disks which can be organized as a RAID-system to extend disk storage space, increase operational speed or enhance storage reliability. Most NAS retailers like Iomega, Synology, Buffalo offer software-based RAID as a function of embedded OS, while others, like Promise, supply hardware-based RAID as well.
NAS storages work with embedded retailer-specific file systems. Most commonly used among them are Ext3 and XFS of special Linux editions. At the same time, such retailers as Adaptec offer BSD-based solutions (e.g. SnapOS) and use custom UFS editions. Modern NAS storages can also use various releases of ZFS file system. The type of the file system of NAS storage doesn't influence access to network files and storage operation, rather data recovery chances in case of storage failures and data loss.
Despite increased reliability of NAS storages, they are still exposed to failures and loss of valuable information. Most typical causes of data loss of NAS storages include system failures, software malfunctions, control board failure or simple human errors.
NAS storages don't provide direct access to their drives, thus requiring to start data recovery process with storage disassembling and connecting its drives to a recovery machine. Please read "HOW TO: Connect IDE/SATA drive to a recovery PC" for detailed instructions. Besides, when you remove NAS drives it's recommended to mark their order with paper stickers or soft ink marker in order to re-assemble the storage properly.
After successful connecting all the NAS drives to a recovery PC, data recovery can be started.
Single-disk NAS and multi-disk NAS with RAID1 configuration contain 'data file system' on data partition of the disk.
Multi-disk NAS of Buffalo, Iomega, Synology etc. employ software RAID built on data partitions of each disk. NAS systems like Promise NAS employ hardware RAID built on the entire disks.
RAID-based NASes, except RAID1 configuration, usually require virtual RAID assembling after what you may proceed to recovery of your files. Please refer to "How to.." articles for detailed instructions for data recovery from NAS storages.