Data recovery in distributed SAN-systems
The idea of storing data in a distributed manner was developed in an application of a Storage Area Network (SAN). SAN-systems create a huge amount of disk space by integrating several servers into one system and allow getting fast parallel access to data from different servers. They are mainly used by corporate users for reliable centralized data storing. SANs operate special file systems and particular controllers to access to storage. Several servers one system and distributed data storing method make SAN a system with high fault-tolerance and greater reliability. Nevertheless, seldom failures of devices still happen. Failure of SAN-controller, inappropriate reaction of the controller to a SAN-component failure and more common operator's errors resulting in data deletion cause loss of critical information in the system.
SAN-systems are unique in the aspect of data recovery due to the non-transportability, thus excluding the possibility to take such system to a server center. Besides, these systems usually store a considerable amount of crucial information making the company operating without this device during a long period of time impossible. In case of metadata outages or failures of controller metadata, the data can be recovered quite rapidly through file system reconstruction on the basis of metadata and its further copying to a safer place. If a SAN-component failed, it's possible to recover the data lost from this component only. If vitally important data was deleted, the system must be switched to the read-only mode at once and you should immediately take copies of metadata and journal of the SAN-system (usually 1-10% of the whole amount of a file system). Data recovery from these systems is available on remote-service basis offered by SysDev Laboratories. When contacting the service you are kindly asked to specify the file system type of SAN and send the metadata image of SAN to test the possibility of data recovery (the metadata do not contain any corporate information and only inform about data distribution and file names on the SAN-system).