[Ian Maclean]

I haven’t been able to find anyone using a nested RAID (such as 10) successfully, so will go with a striped RAID as FCP scratch disk, and conventionally back up that RAID set.

The good news is that all of this becomes obsolete in 12 months or less when Snow Leopard (with Sun’s open source filesystem ZFS) comes out:
https://blogs.zdnet.com/storage/?p=335

“No more Disk Warrior
Data corruption on PCs and Macs is a sad and stupid fact of life. Power failures, flaky RAM, poor grounding, (slowly) failing hard drives, driver glitches, phantom writes and more conspire to rot your data.

ZFS eliminates that. All blocks are checksummed and the checksum is stored in a parent block. ZFS always knows if the block is correct and/or corrupt. Every block has a parent block (with one obvious exception that gets special treatment), so the entire data store is self-validating. You’ll never have to wonder if all your data is correct again. It is.

No RAID cards or controllers
ZFS implements very fast RAID that fixes the performance knock-off against software RAID. In ZFS all writes are the fastest kind: full stripe writes. And the RAID is running on the fastest processor in your system (your Mac), rather than some 3-5 year old microcontroller.

Just add drives to your system and you have a fast RAID system. With Serial Attach SCSI and SATA drives you’ll pay for the drives (cheap and getting cheaper), cables and enclosures.

No more volumes
Every time you add a disk to your Mac you see another disk icon on the desktop. If you want to RAID some disks you use Disk Utility (or something) to create the volume. Slow, error-prone, confusing.

ZFS eliminates the whole volume concept. Add a disk or five to your system and it joins your storage pool. More capacity. Not more management.

Backup made easy
ZFS does something called snapshot copy, which creates a copy of all your data at whatever point in time you want. Copy the snapshot up to a disk, tape or NAS box and you are backed up.

Create a snapshot on every write if you want, so if your database barfs you can go back to just before it choked.”

[Ian Maclean]

I may post a new topic using the name ‘Nested RAID levels,’ which is the topic at hand, according to Wikipedia phraseology:
https://en.wikipedia.org/wiki/Nested_RAID_levels

I’m having trouble understanding these options. I had visualized the setup incorrectly. The diagrams on the Wiki page help a lot. Maybe RAID10 is a better option.

[Ian Maclean]

Thanks for that very useful link, Alan.

I need the same info on RAID setup. I’ve got the Firmtek 5 bay enclosure, and eSata card to augment my Mac Pro Octo. A tech support guy at firmtech recommended the new terabyte drives from Samsung, and at that price and with those good reviews, I just bought five. (five terabytes! I’m pretty stoked).

I want to do high def video editing. I’ve formated the drives (non journaled), and will use a large block size when configuring my RAID setup.

I’d like to stripe two of the drives, and use them as a Final Cut Pro scratch disk. This should be fast enough by a comfortable margin for capturing the 720p 30fps workflow I have in mind. Then I’d like to mirror those two with two more as backup. This would be a RAID 0+1.

Disk Utility can apparently do it (thanks again Alan). However, Firmtek support said they’ve tried it, but haven’t been able to get it to work, and not just on an external enclosure, so I don’t know:

“I tried that Apple Tech note with direct connect and SATA PM enclosures. I even tried it with
internal Mac Pro hard drives. It failed. I asked on the Apple discussion boards and everyone
else that wrote back said they had the same issue.”

I also don’t understand how doing it 1+0 wouldn’t lose the speed advantage of doing the striping first (0+1).

And even doing it 0+1, my concern is that the mirror process is slower than the stripe process, and somehow will slow down read/write speeds to the scratch disk(s). There doesn’t seem to be a lot of experience in this area. I may just backup the first striped pair to others with backup software. Any suggestions from anyone who’s actually gotten RAID 01 working on Leopard most welcome.

[Ian Maclean]

Hm. Not a lot of give and take on this topic. Got another response to a question from Blackmagic, and here it is, with an explanation of the signal path on the Sony camera from the PDF service manual link above:

—————

– I am also unclear about …advertised claims such as “With Intensity, you can now capture AND [my caps] play back full resolution HDTV uncompressed video for true broadcast and feature film quality editing.” We seem to agree that, if the cameras work the way you claim, capturing live / direct is capable of film-quality 4:2:2 colorspace, but can the same be said of ‘play back?’ What is ‘played back’ is compressed footage, and my understanding of the AVCHD codec is that it is 8-bit, 4:2:0, which nobody would call ‘film quality.’

-The HDMI output is just like the component outputs or SDI outputs from other cameras. It is unlike the data output of firewire which is merely the transfer of of bits and bytes from the DV or HDV tape to the computer drive. When you send a signal out of the HDMI port, it is an actual 4:2:2 uncompressed video signal in either YUV or RGB colour space. When you capture ‘live’ from the camera, it bypasses the HDV compression chip on the camera going straight out of the component as well as HDMI outputs of the camera, this is why you don’t see a delay in the video unlike using firewire. This can be seen in the block diagram of the service manual I’ve sent you as well as from tests carried out by us when developing the product. Simply capture HDMI off the camera ‘live’ and then the same video off the tape and you will see the quality difference.

When the video is already recorded to tape, the output is still uncompressed video as the camera processes and upsizes the video in order to send out full resolution HD video. You do lose a bit of quality as some data is thrown away after going onto tape but it is still better than working in AVCHD natively.

Now, let’s take about the capturing process on the Mac. We allow you to capture, with Intensity, to the Apple Uncompressed 8-bit codec. This is a uncompressed workflow running at 120MB/sec of datarate. The video goes in uncompressed and when you edit the video, you play out via the HDMI port of the Intensity card, uncompressed video at its full resolution. This is the ‘played back’ part of the equation. True uncompressed video monitoring of your HD timeline out via HDMI.

…I thought I’ll try and explain the signal flow diagram in the service manual.

Let’s the take the Sony HC5 camera for example. We start off on page 38 and the top left corner of the page where the signal starts at the camera iris and then into the CMOS IMAGER. You’ll need to follow the green video lines here. It then goes into page 39 where the signal flows to the right of the page into BASE BAND SIGAL PROCESSOR (IC2101 (1/5)). Page 40 then shows the signal output from

[Ian Maclean]

Interesting: Sony’s new HDR-SR7 (Expected to ship on or before July 13, 2007), comes with an Optional HDMI Cable – 30ft. (VMC-30MHD). Can there be any other purpose than tethered, live capture? To the Intensity card?

in the Optional Accessories: https://www.sonystyle.com/is-bin/INTERSHOP.enfinity/eCS/Store/en/-/USD/SY_DisplayProductInformation-Start?CategoryName=dcc_DICamcorders_HighDefinitionVideo&ProductSKU=HDRSR7&TabName=specs&var2=

[Ian Maclean]

I’ve been emailed the following from a Blackmagic rep, and wonder if there are any video / electrical engineers that can verify her statement about one of the new Sony cameras. There are a ton of schematics in the PDF, and I don’t know where to start:

“>To check you can download the service
>manual of the Sony HDr-HC5 and HC7 from this page:
>
>
>https://www.humanvalues.net/hdv/Sony_HDR-HC5_HDR-HC5E_HDR-HC7_HDR-HC7E_Service_Manual.pdf
>
>
>This will clearly show the signal path of
>the video which goes from the lens to the HDMI output.”

[Ian Maclean]

“And when I write such things on those forums, all those people who are sooooo in love with 24p react like I just fed ’em a hot fundge sundae topped with sauerkraut.

It’s nice to know that someone else gets it.”

I’m with you. Higher frame rate is better, and I don’t understand, at all, the choice to go 24 over 30 (or higher).

I like showscan. Blew me away, and had me leaning in my seat. 70mm film, 60fps. Eyeballs to brain: this is reality…

[Ian Maclean]

I’d also like to confirm that using any of the camcorders mentioned above, and recording to hard drive / card / dvd, then playing back to Intensity through HDMI output will have lost the 4:2:2 space when the AVCHD compression was done. Even if decompressed into 4:2:2 for playback, my impression is that the colorspace will have, essentially, been ‘up-rezed.’ Do I understand this right?

I”m also guessing that the camera manufacturers don’t really want to encourage this workflow as it would have to eat into the market for their higher end cameras. Any thoughts?