NAS
NAS may refer to any of the following:
1. Short for network access server, NAS is also known as a terminal server and is a computer or network device that communicates you with another computer or service. For example, when you dial in to connect to the Internet, you're dialing into a NAS.
2. Short for network-attached storage, NAS is any storage device that is connected to a network and provides a network with additional storage. A NAS does not have any processing power on its own, meaning it cannot be used to execute or run network shared programs.
FreeNAS
FreeNAS is a free, open-source operating system for NAS (network-attached storage), first developed in 2005 by Olivier Cochard-Labbé. Based on FreeBSD, it uses ZFS to provide flexible, fault-tolerant RAID, and a web interface for remote administrative control of the server. It can boot from a fixed disk, or from a removable device, such as a USB flash drive. A plug-in architecture enables the user to customize what types of data services are provided by the server.
Fault tolerance
Fault tolerance is a quality of a computer system that gracefully handles the failure of component hardware or software. A system can be described as fault tolerant if it continues to operate satisfactorily in the presence of one or more system failure conditions.
Fault tolerance can be achieved by anticipating failures and incorporating preventative measures in the system design. Below are some examples of techniques to mitigate and tolerate failure in a computer system.
1. Power failure - Have the computer or network device running on a UPS. In the event of a power outage, make sure the UPS can notify an administrator and properly turn off the computer after a few minutes if the power is not restored.
2. Power surge - If no UPS connects to the computer or the UPS does not provide surge protection, connected devices are not protected. We recommend a surge protector to help protect in the event of a power surge.
3. Data loss - Run backups daily or at least monthly on the computer if important information is stored on it. Create a mirror of the data on an alternate location.
4. Device or computer failure - Have a second device, computer, or computer components available in the event of failure to prevent a long down time.
5. Unauthorized access - If connected to a network, set up a firewall.
6. Frequently check for updates - Make sure the operating system and any running programs have the latest updates.
7. Lock device or password protect computer - When not in use lock the computer and store the computer or network device in a secure area.
8. Overload - Setup an alternate computer or network device to use as an alternative access point or can share the load either through a load balancing or round robin setup.
9. Virus - Make sure the computer has updated virus definitions.