03-28-2011 06:57 PM - edited 03-19-2019 02:38 AM
Hi all,
I would like to know why in all UC documents, when talking about virtualization, we are explicitly limited to SAN? What is wrong with NAS? I'm looking for good technical reason (i.e. can guess couple sales/presales reasons)....
Thanks,
Tenaro
03-28-2011 07:50 PM
Not sure this is a “good” reason but it is “a” reason and one I know was cited as a concern early on.
SAN allows the server to treat it like a remote disk (i.e. you can access files by blocks and offsets as you would on a hard drive) – the NAS is a file server and typically will have its own file management “head” that takes care of this (i.e. you access files by name to the NAS and it will fetch/write the file for you) – the means you can have a much wider variety of applications/servers using a NAS without knowing or caring – SAN is going to require more work. But on the up side doing things like streaming data to/from the storage facility (i.e. recording/playing back a voice message) gives the application server using SAN much more control over how that is done. Think about control over pre-fetching chunks of a wav file for playback and controlling streaming logic on a long write – the NAS hides all this from the application, you have no control.
A real-world example: I use a NAS at home (2 TB RAID… yes, I need that much space. Really). I can stream 6 or 7 HD TV shows off the NAS to computers/TVs around the house no sweat. However recording HD TO the NAS directly is a disaster – massive file fragmentation even after I fiddled endlessly with various settings and it can’t manage more than 2 at a time without dropping frames. I ended up having to record all streams locally and then copy them over to the NAS as whole files to keep things sane and tidy. If I were using a SAN and had a media capture setup sophisticated enough to use it properly this wouldn’t be a problem.
Understood NAS and SAN are starting to blur as time moves ahead but this is certainly a viable issue to take into consideration.
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