[ENBD] Confussion in ENBD & NFS

[Peter T. Breuer]

"A month of sundays ago Srinivas wrote:"
>    Assume you have two systems A and B are in network. A is nbdserver and B 
> is nbdclient. In that B computer can share A computers  memory. In this case 

False. Two different computers, so they cannot share each others
memory.

You must have misspoken. Maybe you meant something other than "memory"?

> the nfs also does same. I want to know the main difference between nfs and 
> ENBD. plz help me regarding that.

Oh, there is no comparison. An nbd is simply a disk, connected by a
"long pair of wires". It is not shared.

You can read it from multiple locations, but don't expect to write to
it from multiple places and get a lot of sense as a result. Yes, you
can do that if you don't cache it on the clients (i.e. you access
the nbd on the clients via direct i/o or via a raw device binding),
but then you need the application to access the nbd device directly,
without going through a file system, because file systems will do their
own caching. That's OK for database applications.

Peter