Re: RAID HBA options (now Seagate)

Jim,

Your test --
I do have a 58 minute Avid HDV doc on my RAID right now. That's just a couple of minutes shy of your 60 minute test.



What Bob speaks of is true. It will however, also depend on what video formats you use specifically. It has to be understood that EACH of the video formats from Final Cut Pro, have each of their own requirements when it comes to what the latency should be to pass an I/O before the next I/O needs to occur of that chosen format. (If you do not pass 1 I/O before the next is completed, you'll likely drop a frame due to disk latency)

Although you can use a tool like AJA's test to measure what you're raid will read/write - I do know that it pop's out what is usually a full bandwidth number of the raid, not a latency number of the disks. However, with that said, there's a lot of way's to test latency on the disks, and yes, running a video stream can certainly test it.

It would be too general to say that if you have a raid and you try to edit video on the raid and you drop a frame that your raid is truly the problem....
With that said, assuming the RAID is in fact fast enough, and you still have latency issues (completely possible). Well, then that's when you start forking out monies and putting the combination of hardware together to give you what you are looking for in the overall profile to meet the performance (disks, raid controllers, back-planes, motherboards, network ports...etc etc..) (be prepared to go through many configurations before finding one that works for your "preferred latency" performance number) ---

It should also be noted that vendors do a fair amount of "testing" prior to you purchasing their solution. This is "simulated" testing. (It's simulating a controlled environment, not your actual "working" environment) -- In simulation applications, 'latency' refers to the time delay, normally measured in milliseconds (1/1,000 sec), between initial input and an output clearly discernible to the simulator trainee or simulator subject.

Believe it or not -- the I/O requirements vary between video formats .... So it would be a valid comment to say you could likely put 10 x DV25 Streams on a RAID, that will only support 2-3 Streams of Pro Res... I'm trying to make the point that if one RAID is able to to XYZ, the same RAID under another condition may only do X, or Y, or Z, not all three together.



I hope this helps make sense..