- An explanation of storage area networks and network-attached storage
- Getting started with storage. Understanding SAN vs NAS vs DAS.
- SAN vs NAS - Difference between a Storage Area Network and Network Attached Storage
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- NAS vs DAS vs SAN
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- DAS vs NAS vs SAN | difference between DAS,NAS,SAN
- San vs nas vs das pdf converter
- SAN vs. NAS vs. DAS: Competing or Complementary?
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- Difference Between SAN and NAS
If you are managing your own infrastructure in your own private data center, then you are bound to go through a selection of different storage offerings. Selecting a storage solution pretty much depends on your requirement. Before finalizing a particular storage option for your use case, a little bit of understanding about the technology is always helpful. I was actually going to write an article about object storage which is the current hottest storage option in the cloud.
But before going and discussing that part of the storage arena, I thought its better to discuss the two main storage methods which co-exists together from a very long time, used by companies internally for their needs.
An explanation of storage area networks and network-attached storage
The decision of your storage type will depend on many factors like the below ones. Type of data that you want to store. And without a little bit of digging, you are bound to get confused with different terms in storage. The confusion arises often because of the similarities between the different approaches in storage. The only hard and fast rule to stay up to date in technical terms, is to keep on reading stuffs especially concepts behind a certain technology.
Getting started with storage. Understanding SAN vs NAS vs DAS.
Today we will be discussing two different methods that defines the structure of storage in your environment. Your choice of the two in your architecture should only depend on your use case, and type of data that you store.
By the end of this tutorial, I hope you will have a clear picture about the main two types of storage methods, and what to select for your need. The main things that differentiate each of these technologies are mentioned below.
SAN vs NAS - Difference between a Storage Area Network and Network Attached Storage
How a storage is connected to a system. In short how the connection is made between the accessing system and the storage component directly attached or network attached. Type of cabling used to connect. In short this is the type of cabling done to connect a system to the storage component eg. How are input and output requests done. In short this is the protocol used to conduct input and output requests eg.
Related: How to monitor IO on linux. Let's discuss SAN first and then NAS, and at the end, let's compare each of these technologies to clear the differences between them. Today's applications are very much resource intensive, due to the kind of requests that needs to be processed simultaneously per second.
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Take example of an e-commerce website, where thousands of people are making orders per second, and all needs to be stored properly in the database for later retrieval. The storage technology used to store such high traffic data bases must be fast in request serving and response in short it should be fast in Input and Output.
Related: Web server Performance test. SAN is nothing but a high speed network that makes connections between storage devices and servers. Traditionally application servers used to have their own storage devices attached to them.
NAS vs DAS vs SAN
SCSI is nothing but a standard used to communicate between servers and storage devices. All normal hard disks, tape drives etc uses SCSI.
In the beginning the storage needs of a server was fulfilled by a storage devices that was included inside the server the server used to talk to those internal storage device, using SCSI. This is very much similar to how a normal desktop talks to its internal hard disk.
The main advantage of SCSI for connecting devices to a server was its high throughput. Although this architecture is sufficient for low end requirements, there are few limitations like the below mentioned ones. Low complexity, Low investment, Simplicity in deployment caused DAS to be adopted by many for normal requirement's.
The solution was good even performance wise, if used with faster mediums like fiber channel.
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Internally the storage device can use RAID which normally is the case or anything to provide storage volumes to servers. To the server, a DAS storage will appear very much similar to its own internal drive or an external drive that you plugged in. Although DAS is good for normal needs and gives good performance, there are limitations like the number of servers that can access it.
Storage device, or say DAS storage has to be near to the server in the same rack or within the limits of the accepted distance of the medium used. It can be argued that, directly attached storage DAS is faster than any other storage methods.
This is because it does not involve any overhead of data transfer over the network all data transfer occurs on a dedicated connection between the server and the storage device.
DAS vs NAS vs SAN | difference between DAS,NAS,SAN
However due to latest improvement's in fiber channel and other caching mechanism's, SAN also provides better speed's similar to DAS, and in some cases, it surpasses the speed provided by a DAS. Before getting inside SAN, let's understand several media types and methods that are used to interconnect storage devices when i say storage devices, please dont consider it as one single hard disk. Take it as an array of disk's, probably in some RAID level. Consider it as something like Dell's MD But shared parallel connections are not good for high accuracy, and create issues during high speed transfers.
However a serial connection between the device and the server can increase the overall throughput of the data transfer.
San vs nas vs das pdf converter
Think of SCSI bus that shares the same speed for all devices connected. Also please do not think that SCSI is only used for internal storage. It is also used for external storage device to be connected to the server. If data transfer performance and reliability is the choice, then using SAS is the best solution.
SAS was designed by keeping performance in mind, due to which it is full-duplex.
This means, data can be send and received simultaniously from a device using SAS. Fiber Channel is a relatively new interconnection technology used for fast data transfer.
It can be used to interconnect workstations, peripherals, storage array's etc. When we say Fiber in Fiber channel do not think that it only supports optical fiber medium. Fiber is a term used for any medium used to interconnect in fiber channel protocol.
You can even use copper wire for lower cost. Please note the fact that fiber channel standard from ANSI supports networking, storage and data transfer.
SAN vs. NAS vs. DAS: Competing or Complementary?
Fiber channel is not aware of the type of data that you transfer. The components of making a fiber channel connection are mentioned below. The below requirement is very minimal to achieve a point to point connection. Typically this can be used for a direct connection between a storage array and a host.
Cables to interconnect devices in HBA fiber channel port. As mentioned earlier, SCSI protocol is encapsulated inside fiber channel. So normally SCSI data has to be modified to a different format that fiber channel can deliver to the destination. And when the destination receives the data it then retranslates it to SCSI. You might be thinking that why do we need this mapping and re-mapping, why cant we directly use SCSI to deliver data.
Its because SCSI cannot deliver data to greater distances to large number of devices or large number of hosts.
Fiber cannel can be used to interconnect systems as far as 10KM if used with optical fibers. You can increase this distance by having repeaters in between. And you can also transfer data to an extent of 30m using a copper wire for lower cost in fiber cannel. With the emergence of fiber channel switches from variety of major vendors, connecting many large number of storage devices and servers have now become an easy task provided you have the budget to invest. The networking ability of fiber channel led to the advanced adoption of SAN Storage Area Networks for faster, long distance, and reliable data access.
Most of the high computing environment's which requires fast and large volume data transfers uses fiber channel SAN with optical fiber cables. This is the simplest and cheap solution although not the best to connect to a storage device.
This is a nice technology for location independent storage. Because it can establish connection to a storage device using local area networks, Wide area network.
Its a Storage Area Network interconnection standard. It does not require special cabling and equipments like the case of a fiber channel network. To the system using a storage array with iSCSI, the storage appears as a locally attached disk.
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This technology came after fiber channel and was widely adopted due to it low cost. You can guess that its not at all good performance wise, when compared with fiber channel simply because everything is running over TCP with no special hardware and modifications to your architecture. The simplest definition of NAS is "Any server that shares its own storage with others on the network and acts as a file server is the simplest form NAS".
Please make a note of the fact that Network Attached Storage shares files over the network.
Not storage device over the network. NAS will be using an ethernet connection for sharing files over the network. When you access files on a file server on your windows system, its basically NAS. The main difference is in how your computer or the server treats a particular storage. If the computer treats a storage as part of itself similar to how you attach a DAS to your server , in other words, if the server's processor is responsible for managing the storage attached, it will be some sort of DAS.
Directly attached storage DAS can be viewed as any other peripheral device like mouse keyboard etc. However NAS is another server, or say an equipment having its own computing features that can share its own storage with others.
A DAS storage device appears to the server as part of itself.
Difference Between SAN and NAS
The server sees it as its own physical part. Although the DAS storage device might not be inside the server its normally another device with its own storage array , the server sees it as its own internal part DAS storage appears to the server as its own internal storage. When we talk about NAS, we need to call them shares rather than storage devices. Because NAS appears to a server as a shared folder instead of a shared device over the network.
Please do not forget the fact that NAS devices are computers in themselves, who can share their storage space with others.