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NFS-SAN-NAS-brief storage concepts overview to the new oracle dba

you are a new oracle dba and you would like to know the storage concepts like SAN,NAS or NFS.

NFS = “Network File Service”. This is a protocol that delivers “exported” disk filesystems to the network, to be “mounted” by UNIX (or PC) clients. NFS was invented by Sun Microsystems and has been around for over 15 years. The latest version of NFS (produced in the last few years) provides significant performance and reliability enhancements. ¬†NFS is a “file level access protocol”, because you read data as files via the client O/S.

NAS = Network Attached Storage. “NAS” is a euphemism for iSCSI, the dominant NAS protocol. This is a way to provide access to a storage device for a client (usually a corporate server) that makes the storage on the storage device look like a local disk drive to the corporate server. Microsoft gives away the Microsoft iSCSI Initator which is the client piece that can “pick up” the “LUN” from the NAS device. The big advantage here is that you can provide this seemingly-local disk storage to your corporate servers over plain, ordinary ethernet wiring and switchgear. NAS is a “block level access protocol”, just like SCSI. The corporate server reads the data from the storage device in blocks, not at the file level.

SAN = Storage Area Network. A “SAN” is the hardware equivalent of NAS, but it does not work over ethernet. SAN hardware is a storage device that attaches to the client using optical or copper Fibre Channel links which can be provided by a Fibre Channel Switch like a Brocade. SAN hardware is the fastest of the three remote access methods I mention here, and is usually the most expensive. SAN access is “block level” just like NAS. SAN device technology is older and more established among corporations that can afford it.


When you share a folder in a Windows environment, you are using “CIFS” or Common Internet File Service. This was a name Microsoft chose for SMB, the Server Message Block protocol. (sorta where the name for SAMBA came from). CIFS is a file level sharing protocol, which makes a folder available across the network. It works at the same level as NFS. Just as NFS comes “free and built-in” with UNIX/Linux, CIFS comes free and built-in with Windows.

While you did not use NAS, SAN or NFS to make that folder available over the network, when the folder was shared from one computer, that computer became The Server, and the computer that received the folder became The Client. The act of sharing the folder committed The Server to the task of sharing the folder to at least one other computer, The Client, so in a way similar to NAS/SAN/NFS, there was a commitment of hardware resources on the server for providing that disk space to the client. Now, if The Server goes down or fails or is powered off or loses it’s connection, The Client is negatively impacted. That’s why servers tend to be configured differently, with multiple power supplies, multiple network connections and multiple disk drives, usually in a RAID configuration.

NAS, SAN, and usually NFS, all require that a company makes a siginficant, directed investment in server hardware that is as reliable as reasonably possible. CIFS shares require that also, but since CIFS comes free on any Microsoft PC operating system, you can choose to share a file with no commitment to reliablity at all. And for only a few people, or even one person, that might be just fine.



-CIFS is built-in microsfot operating systems,
-NAS and SAN they are hardware with software already installed on it
-NAS uses Cat5 or SCSI wires to connect disk array chassis to the server. is there any hardware in between?is there any software in the disk chassis?
SAN uses Fiber Channel to connect the disk array chassis to the server with FC switch in between. is there any software in disk chassis?

I was curious about some jobs where they require knowledge of SAN or NAS, I don’t know what is needed as knowledge to be a SAN or NAS guy.


Right: CIFS is built-in to Microsoft operating systems and shares directories (folders) from one computer to another.
Right: NAS and SAN are hardware that holds the data to be shared. The client has a small piece of software called “iSCSI”.
Right: NAS systems work over ethernet networks: CAT5 wiring, ethernet switches.
Wrong: Systems that use SCSI cables are “DAS” systems – Direct Attached Storage.
Right: SAN uses Fibre Channel to connect to the server. There is usually some kind of FIRMWARE or Operating System in a SAN that makes the data available to the client.

For the jobs: You need to have experience with:
SAN: EMC “Symmetrix”, EMC “Clariion” and IBM “FAS-T”, etc.
NAS: EMC Clariion, Network Appliance, etc.

There are various software pieces that run both SAN and NAS that you would want to know about. For example, EMC “Symmetrix” uses “TimeFinder” to make the BCV’s happen.



I have seen SAN network used with tape library, the connection route is:

Servers(have FC adapters)———>Brocade Switch——–FC Switch( it has one FC Module and one SCSI Module)——–>Tape library(through SCSI module)
——–>Backup server(through FC Module)
**we could have disk array chassis instead of the tape library

It seems like I know the route for the SAN. but never configured it.
I want to know if there is any software to install in the servers that have FC Adapters.
the only thing I know is there is a web interface to configure the Brocade switch for zoning and the FC switch so that it communicates with tape library drives and the backup server.

if we had disk array chassis instead of the tape library, do we have to install any software in the disk array chassis? do we have to share dives/folders in the disk array so that other servers/workstations can access?

if you would illustrate the connection of the NAS , that would help also.



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