NAS vs SAN - File vs Block level data access

[Alex Filacchione]

So can/do NLEs access video data on a video server at the block level?

The big diff between NAS & SAN is that NAS is file-level access whereas SAN is block-level access to the data.

When an editor is pulling video off of a server for use in the NLE, is he pulling the entire video file over, or is it possible to pull over just blocks of data?

SAN definitely makes sense for things like an Exchange server or databases, etc. where you can access data in small chunks rather than pull the entire database over. However for video editing can you take advantage of this or not? I know when I import video from my local disk into an NLE it imports the entire video file, not just a chunk that I may be editing. IOW, when dealing with local video I seem to be dealing with file-level access, not block level. I can only assume that the same thing ocurrs over a LAN be it a SAN or NAS setup.

Thanks for any clarification,

Alex F

[Chris Hurd]

Er... eh... would this be PC or Mac?

[Alex Filacchione]

Well, let me put it this way, is there really ANY NLE out there that access video off of servers at the block level rather than the file-level?

I haven't seen an NLE that can access just a small snippet of a video file rather than the whole thing, w/o actually grabbing the whole file. This is even more difficult from an NLE persepctive w/ compression & GOPs I would imagine. Everything I've seen grabs & imports the video file into the MLE and then you can edit clips out of it. Furthermore if you COULD access the video at the block level you would have to somehow view the whole thing in order to see which snippets you want (it's not like a DB where you can run a query and just grab certain portions of the DB). In order to view the whole video to grab the snippet you want, you would have to pull it over anyway.

Of course, I haven't used something like an Avid Symphony or DS system. Just XpressPro and PremierePro, so I don't know how something like that or a quantel system would handle it.

The only way I could really see block-level access working efficiently for video is if you are looking at or editing a low res version, and then use timecode to determine which "blocks" of video data you need in fullres.

Then again, when editing video you are mostly pulling a file over, opening it up locally, and then spending time editing it. WHen you are finished you would check it back in. At least that's the way it is w/ file-level access. IN that case, you can fill up your network bandiwdth pipe, but it's only temporarily, not sustained like very high traffic databases, etc.

As far as the network and the SAN or NAS itself is concerned, it doesn't care what OS you are using for the most part, ESP, if you are doing this over TCP/IP. I think what matters is how the NLE can access the data.

Alex F