Data storage is generally classified as primary storage or secondary storage, with primary storage is that which is accessible by the processor of the computer or server and secondary storage is not generally accessible by the processor and to store all operating system and application programs for personal data of users. It is a non-volatile memory, and retains its state even after power off.
The area of ??main storage in modern computers can be accessed from the processor is usually called RAM or Random Access Memory, which is a volatile memory used to store the commands of the CPU. This type of memory, often called “memory” is volatile and is erased whenever the computer is off. Most computers and servers now use a form of RAM than DRAM (Dynamic RAM), where the computer used to access known input / output channels to memory.
An extra storage in a computer as a ROM (Read Only Memory) that is primarily used to create a boot file, which is commonly (Basic Input Output System) is known as the BIOS used to start the store of computer known.
The rest of this article will focus on the storage of operating systems and application programs and data sub-title, DAS (Direct Attached Storage), NAS (Network Attached Storage) and SAN (Storage Area Network) concentrated using Fibre Channel.
Direct Attached Storage refers to storage media that is in the computer or server or computer peripherals such as keyboards. The data passes through the CPU, memory, and then by bus to the storage medium like a hard drive. A RAID controller can be used to help organize data across multiple hard disks and providing redundancy and reliability. Files to secondary storage systems must be organized for easy reading and writing, just file a formal system is required to do so. The data are organized into folders and files, to facilitate the location of data. Additional memory may be made available in the form of flash drives, tape drives or ZIP drives.
Network Attached Storage, NAS, or as it is called, is a method of storing data on a data network where the server contacts the remote NAS server is located in a TCP / IP. Could be the server, Windows, Unix or Linux, designed around common file sharing protocols such as NFS or CIFS host. A further development is the use of appliance servers that have a very basic operating system that is specifically designed to be supported file-sharing protocols to do so.
Must be SCSI commands, the commands block-level protocol for file-level to implement in order to be passed through the TCP / IP and converted to level SCSI commands to lock it when they received the NAS server .
The server only needs one NIC (Network Interface Card) to the NAS server via TCP / IP network, which also need a network card to communicate. NAS is a very common storage solution for small businesses and organizations as well as large corporate networks used. A major problem in the NAS is the most important overhead in terms of protocol conversion to take place when data is sent and received. Fast network connections are required if the data is within acceptable limits, and even 10-Gigabit Ethernet or Gigabit Ethernet provide power for a reliable, fast read and write data transfer required.
An alternative to the standard network-attached storage, iSCSI, which is a standard method for encapsulating SCSI commands in TCP / IP and the need for protocol conversion file. iSCSI was the true precursor of Storage Area Networks by extending the local bus via a network connection. For iSCSI to work effectively, it is advisable to run on a dedicated network or subnet.
While modern networks of storage area network using a dedicated Fibre Channel technology works. Fibre Channel networks are specifically designed for the transfer and retrieval of data from the storage servers. Resilience can be provided by redundant paths to and from the servers, so that no “single point of failure” scenario. The main advantages of Fibre Channel are:
• Speed ??of data transmission, which is 2 Gigabit Fibre Channel 2.
• The number of devices can be connected in the network is 127, which is a multiple SCSI.
• The distance between servers and storage systems can be a bit like 10 km, giving a high degree of flexibility and options when choosing to site server and a storage building.
• Fibre Channel switches for hundreds of hard drives are connected in multiple arrays or clusters.
Fibre Channel has many advantages over other systems such as SCSI and iSCSI, and is the storage system of choice for today’s medium to large enterprise networks, but also other systems such as storage attached to the traditional network will continue to be the mainstay for small businesses and networks for some time.