A Specified Comparison between NAS and DAS

Posted by @AOMEI

October 19, 2016

NAS and DAS are two common ways for data storage. Both have their own strength. But when asking which one is better, maybe there is no standard answer. However, a comparison of the two is still necessary.

With the increasingly close combination of IT and enterprise management, the data of small and medium-sized enterprises are in a rapid growth, network data security has become particularly important. The damage or loss of important data will cause significant influence to enterprise, or even irreparable damage. But how to ensure the safety of data, how to do data disaster backup, and what kind of storage should be chosen have become the common problem for small and medium-sized enterprises. Currently, the enterprise data storage is usually divided into three kinds, respectively: DAS, NAS and SAN. This article mainly talks about the difference between NAS and DAS.

About DAS and NAS

DAS (Direct Attached Storage) is one of the Storage solutions. The server structure of this storage solution is similar to PC structure, external data storage devices (such as disk arrays, optical drives, tape recorders, etc.) are directly articulated within the server bus. The data storage device is a part of the entire server structures. The server also shoulders the responsibility of the whole network data storage. This direct way of DAS can solve the problem of the space extension of single server storage, as well as high performance transmission requirements. The capacity of a single external storage system, has been developed from 1 TB to 2 TB, with the launch of the large capacity hard disk, a single external storage system capacity is still rising. In addition, DAS can also constitute a double machine high availability system based on disk array, thus meet the requirements of data storage for high availability.


NAS (Network Attached Storage) comprehensively improve the inefficient storage way of DAS previously. It adopts a kind of file server that is specially developed for network data Storage and is independent of the PC server. All of the network data storage devices (such as a variety of disk arrays, tape, we, etc.) are concentrated in the NAS server, thus the storage capacity can be well extended. At the same time, due to this way of network storage is independently assumed by NAS server, so basically there is no influence for the performance of the original network server. And the entire network performance is not affected. NAS provides a simple, cost-effective, high availability, high scalability, and low total cost network storage solution.


Difference between DAS and NAS

For the environment that has more than one server or PC, DAS equipment may cost lower of the initial fee, but in this connection mode, each PC or server has its own storage disk alone, which causes it difficult for the redistribution of capacity. For the storage system management of the whole environment, there is no centralized management solution, making the management work tedious and repetitive. So the overall cost of ownership (TCO) is relatively high. Today DAS is basically replaced by NAS. The following is the comparison of DAS and NAS.

DAS is the most basic level of storage, in which storage devices are part of the host computer. DAS direct storage depends on the server host operating system. Data backup and recovery take up the server host resources, usually from 20% to 30%, so many enterprise users' daily data backup are often done when business system is not busy, so as not to affect the normal business system running. Direct storage, the greater the amount of data backup, the longer the recovery time, and the greater the dependence and the impact on the server hardware. This scheme is mainly used on early computers and servers, due to the demand for data storage is not large, the storage capacity of a single server need can meet the demand of daily data storage, therefore is quite common in the low network application.

As a network-attached storage devices, NAS devices build in optimized and independent store operation system, thus can effectively release system bus resources, and fully support the I/O storage. NAS equipment is mainly used to implement file sharing applications in different operating system platform. Compared with the traditional server or DAS storage devices, NAS equipment is very simple in installation, commissioning, using and management. NAS data storage scheme is designed based on local area network (LAN), according to the traditional TCP/IP protocol to communicate. And its data transmission based on file I/O. In a LAN environment, NAS can completely realize the level of data sharing between heterogeneous platform, such as sharing in Windows NT, Linux and UNIX platforms. Based on this kind of reason, the cost of equipment management and maintenance for enterprise use is very low.

Bottom line

From the discussion it is quite evident that Network Access Storage is an attractive investment. Not just it delivers great value but also you can store your data in a more secure way. NAS boasts its own OS, processor and RAM which may cost you some initial investment but for the long run it offers satisfactory performance.