Introduction to Web Hosting
I learned about the three types of Cloud Storage. DAS/SAN and NAS. All three types are a result of evolution over last few years. In the beginning there was only a server, which had to add physically install new drives to increase the storage space. This was a hassle to manage at a large scale
DAS: Is a directly attached storage, which is plugged in to the machine physically over a SCSI (small computer systems interface) connection over a USB or any number of other technologies. Unfortunately this does not have the ability to scale and creates a nightmare for administering management location because of the number of DAS required is connected to thousands of server. Because of this limitations they evolved to
SAN: Plugged in a special adaptor on to the server and those adaptors are called HBA (host bus adaptors), are connected to a very special network dedicated to storage called SAN (storage area network). Attached on this SAN is a very expensive large storage solution that would allow multiple servers connected to the SAN to access a centralized storage solution (which can also be maid a RAID - redundant array of independent discs) this SAN storage helps to build all the redundancy, management locations and administration in a single location still giving a flexibility by mapping a LUN (logical unit), the only limitation was that it is very expensive. This limitation led to the evolution of
NAS: Network attached storage, this storage system uses the existing highly available network which is being used for data, voice internet access for number of years so they converge the SAN into existing LAN and to this space attache a highly available RAID solution which is made available via existing LAN network. Here there is still a flexibility to connect multiple servers, however the limitation is that your existing LAN traffic has to compete with NAS traffic and hence priority over NAS traffic over LAN traffic is to be considered
Important consideration to keep in mind while considering any of the above storage solutions is the protocol, for example for SAN the best performance will come from Fiber channel and for NAS the best performance will come from Fiber channel over Internet protocol.
