[David Roth weiss]

First, do you have ANY other FireWire devices plugged in?

Second, is the Startech enclosure possibly 3G, not 6G? (Some 3G devices can accommodate 6G drives, but at 3G speeds, while others are simply incompatible with newer 6G drives.
(***FYI, I just checked, and your Startech array does have a 6G backplane.)

Also, when you purchase the least expensive consumer solutions they sometimes fail to operate as expected in a video-centric domain, because they were not designed for high demands required by video.

There are many really good video storage companies advertising here on the Cow, and they specialize in fulfilling the needs and expectations of professional editors like yourself – when users try do it yourself solutions using consumer parts they typically have only a 50/50 chance of success, and when they fail that costs both time and money. The bottom line is, venturing into untested waters in our business is “false economy.”

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[David Roth weiss]

There are numerous issues with Yosemite and FCP 7 discussed here almost every day. It really should be considered non-functional. Some friends folks have not encountered issues, but the vast majority have.

If you didn’t clone your hard drive before installing the update you should have, and in the future you should always clone first so you can go back if the update wrecks your system.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[David Roth weiss]

mLink makes a nice T-bolt expansion chassis that’s also more cost-effective than most.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[David Roth weiss]

Could be any number of issues, but without telling us the specs of your system, including media drive config and GPU, etc. there’s no way to help you.

Also, what media type are you editing?

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[David Roth weiss]

I prefer Areca cards these days… And, for delivery, you deliver on hard drives these days – FireWire 800, eSATA, USB 3.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[David Roth weiss]

Expensive indeed, but much more expensive when adding a server to the equation.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[David Roth weiss]

RAID arrays do loose throughput as they fill up, it’s the nature of disk storage. There are some schemes, such as the one advertised by Facilis, which intentionally fragment data evenly across inner and outer portions of the disks, but that’s pretty much a marketing gimmick. Leaving 10 to 20% free space is advised by most manufacturers.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[David Roth weiss]

He does not require a NAS unless he plans to share the storage with other users, and he would most likely require expensive 10GB connectivity to handle the 4K material. See my initial response for direct attached storage, which is s much less expensive solution because it does not require an expensive server.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[David Roth weiss]

To accommodate a project of120GB plus overhead (you can’t fill the drives completely), renders, etc. you are going to require at least two 16-drive SAS enclosures, most likely filled with the new 6tb SATA drives, and an Areca or ATTO SAS controller card. Since it sounds as if storage is not your area of expertise, you should definteky call one of the many storage companies advertising here, as you should not try a build it yourself solution.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[David Roth weiss]

You have not mentioned your GPU anywhere in your post. So, please tell us so we can help you.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.