What is the difference between block I/O and file I/O transfer? I heard that NAS and DAS uses file I/O and SAN...
By submitting your email address, you agree to receive emails regarding relevant topic offers from TechTarget and its partners. You can withdraw your consent at any time. Contact TechTarget at 275 Grove Street, Newton, MA.
uses the block I/O method. Please explain in detail since I am learning about this subject as we speak. Thanks!!
NAS does file I/O while SANs typically do block I/O. File I/O is referencing data as a file entity from a remote file system. When referencing a file, an application uses a "file handle:offset" which really is the name of the file and the number of bytes into the file for access to data. For NAS, a redirector diverts the access from a local file system to a remote file system that is accessed across a network usually through TCP/IP over Ethernet. The NAS device turns the remote file system access into its own local file system access that results in a block I/O to attached devices. For a SAN access, usually a block I/O is done where the application will access the file, the file system on the local server will turn that into a request for a block on a particular device (LUN - logical unit) and then block I/O is done over an interface such as Fibre Channel.
The bottom line is that file I/O eventually (and always) turns into a block I/O -- locally it's done through the file system, for NAS it's redirected to a NAS device to do it on a remote system.
Evaluator Group, Inc.
Dig Deeper on NAS hardware
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.