Cf Raid

[Gavin Greenwalt]

Until the announcement that RED would support CF I hadn't payed much attention to the format. I was quite surprised to see that there are CF cards out there with 22MBs read speeds. (Or at least that's what they're advertising).

I would absolutely love to buy a CF RAID box. Here's what I'm thinking:

(two)(20 2GB CF cards at 20MBs for $400 + a $200 20 port CF RAID reader with ESATA outputs.) = $1200

For $1200 bucks I could be running 80GBs at let's say 800MBs. At 20MBs for for $20 that's almost twice the data rate per $ vs 10k hard drives... so what am I missing?

Obviously you lose significant capacity per $ but for my applications 80GB would be enough. So there must be a catch besides the lack of (What seems like would be a simple task of creating) a CF external RAID box.

 

[Tom Lowe]

Some type of Flash/RAM RAID box that attaches to the camera seems to be the only hope for achieving write speeds fast enough to overcrank 4K without an actual data port and RAID computer tethered on set. Where do you get this 800MB/s number?

 

[Gavin Greenwalt]

Well let's just say you pack in 10 cards in to 4 boxes all in RAID0 x 20MBs each = 800MBs theoretical speeds.

Flash doesn't really have a min/max speed like a hard drive so if they actually are 23MBs read flash cards (133x) like they claim... then minus RAID inefficiencies (same as with a normal HDD array) you're still looking at a rediculously fast array for realllllly cheap.

I was just shopping for a new SD card and saw how dirt cheap cards have gotten as of late. $20, 2 GB and supposedly 23MB read speeds.... that's just asking to be exploited.

 

[Charles Perkins]

...

 

[Gavin Greenwalt]

Ok I'm getting closer to seeing what it would take to make this feasible:

http://www.buyextras.com/cotoidead.html it seems like in the future perhaps CF Card -> SATA adapters could reach $3 as well. So that's an additional $3.

Ok here is what you could theoretically do right now if you could find a SATA adapter for as cheap as an IDE adapter (Someone get on that right now.

3 x Areca ARC-1160ML 16pt MultiLane SATA RAID Controller @ $978 ($3000)
48 x 2 GB(20MBs CF Cards) @ $23. ($1100)
= $4100

This would completely theoretically (or more likely not) deliver:
96 GB @ 960 MBs if everybody delivers as advertised. And for an extra $1000 you could bump that up to almost 200GB.

 

[Tom Lowe]

drive speed is not the bottle neck that is stopping people over cranking at 4K. it is the processor in the camera that is the bottle neck.

we are aware of the processor's limitations; that is why people are searching and brainstorming to come up with a solution for recording very high data rates onboard.

yes, write speed is the bottleneck for recording 4K uncompressed, overcranked footage "onboard".... nothing available now can record fast enough to capture 600MB/s-900MB/s uncompressed data onboard the camera, which is why you would need to tether it with the (expensive) data port to a RAID computer on set. very impractical.

 

[Tom Lowe]

Ok I'm getting closer to seeing what it would take to make this feasible:

http://www.buyextras.com/cotoidead.html it seems like in the future perhaps CF Card -> SATA adapters could reach $3 as well. So that's an additional $3.

Ok here is what you could theoretically do right now if you could find a SATA adapter for as cheap as an IDE adapter (Someone get on that right now.

3 x Areca ARC-1160ML 16pt MultiLane SATA RAID Controller @ $978 ($3000)
48 x 2 GB(20MBs CF Cards) @ $23. ($1100)
= $4100

This would completely theoretically (or more likely not) deliver:
96 GB @ 960 MBs if everybody delivers as advertised. And for an extra $1000 you could bump that up to almost 200GB.

COULD IT BE??... have you found the Holy Grail???

 

[Gavin Greenwalt]

Just found a CF card which claims 30MBs or in our ficticious raid 1400MBs.

Hmmm I have my doubts.

 

[Tom Lowe]

edit: hhmm... i thought this was discussed recently, but I can't find the thread.

can anyone raise technical objections to the idea of putting a bunch of high-speed CF cards into a RAID array onboard for super-high-speed, uncompressed data recording? where would the bottleneck be?

I guess this could also tie into the ongoing "RAM buffer" discussions, whereby flash or RAM media would store 30 or 60 seconds worth of 900MB/s uncompressed footage, then slowly feed it out to the camera's processor for recording to the standard Red Drive at 27MB/s (or whatever it is). In this case, you would shoot to your CF cards, then dump the cards slowly through the processor to be converted to REDCODE RAW and recorded to the camera's standard harddrive...

 

[david farland]

note: data limit on 1 sata channel is 375MB/sec.

DF

 

[Gunleik Groven]

The technical objection is quite easy... It all depends on wether the Red enclosures are "smart" or "dumb".

If the Red acts like a computer and can format and RAID "any" SATA device, then you basically connect... welll you guessed it - "any SATA device" including your CF RAID.

My guess though, is that the Red enclosures are partly "smart".

In that case, you must use one of them, with their built in limits and options.
We'll hopefully know @ NAB.

Gunleik

 

[Gavin Greenwalt]

I was thinking more along the lines as hooked up to a computer attached to the optical data port or else for my fx workstation as an attached raid for whatever shot I'm currently working on. This would be an exercise in overkill if I were to use it for redcode footage.

That being said I probably wouldn't even explore it for the optical data port because the money could be perhaps better spent on a good processor to just handle the REDCODERaw Conversion in real time. Just because an onboard DSP can't handle real time encoding doesn't mean an 8 core GPU touting modern workstation can't.

Can we get an official word on whether RED will offer a Workstation side application to interface with the Optical Data port? Will this interface include some basic software for capturing and encoding? If it exists does it include redcode software? Surely you guys weren't testing the prototypes using the actual hardware encoders, you had a software version as well right?

- SATA II is limited to 3.2Gbps per channel. In this case it would be 48 channels or about 15 GBps