Data Storage Bases
Good afternoon, Habr! Do you know what sells HP except printers? And Dell, besides laptops and monitors? And Hitachi, except for domestic equipment? What do these companies and EMC have in common? The answer seems simple to specialists, but not so obvious to an IT specialist.
All listed companies sell (i.e.) data storage systems. What systems? Yeah, in my experience, I found that the knowledge of the storage of most of the IT engineers I know ends in the RAID area. That was the idea of writing this article, or even a few. To begin with, we will consider a number of information management technologies, see what data storage approaches exist and why each has not been sufficient. It describes the basic principles of DAS, NAS and SAN, so it's likely that this article will be useless if you're not close to it, but interesting, welcome!
Introduction
The purpose of the article is to consider the conceptual framework of approaches to Building storage systems data. There are deliberately no technical characteristics, since they have nothing to do with them. The article does not appear to be an advertisement booklet, there will be no names of products, as well as the " good " and " no equivalent " stages. The exhausting article can also be described, on the contrary, I have sought to cover the minimum material available for understanding an average engineer who has never been involved with the CCM. Okay, let's go.DAS (Direct Attached Storage)
This thing is a long time ago. Remind the normal PC disk schedule: the mother ' s fee is connected to HDD through the ATA/SATA interface. You've known all this for years, which means you know what DAS is. Well, you know what DAS architecture is. Internal Like. There is also a DAS architecture external a type which differs from the inside allowed distance between, in general, several servers and the storage device.
External connectivity is achieved through the use of SCSI and FC technologies. If you do not fit into the details of the listed data transmission technologies, that's probably all you can say about DAS.
From the basic simplicity of the DAS architecture, its main advantages are: the lowest price compared to the rest discussed below and the relative simplicity of implementation. In addition, such a configuration is easier to manage because at least the number of elements of the system is low. Data integrity in DAS is ensured by the use of old and popular RAID technology.
However, such a solution would be appropriate for relatively non-critical tasks and a limited number of work stations. The sharing of final computing resources imposes a number of constraints. The number of cars connected does not exceed the number of ports in the storage device, limited capacity increases reading time (IO), inefficient use of the heel, etc.
Partial productivity problems can be solved by a server fleet (e.g., separated by type of query processed), each of which loads a separate storage device.
