what RAID scheme???

[Bob Woodhead]

Mode 3 uses what’s called parity to give a certain amount of data redundancy. Basically, in a 5 drive RAID 3, if 1 drive fails, the data is still safe. You replace the failed drive, and the RAID rebuilds the lost drive’s data. Once it’s rebuilt, you’re back to full speed. Though it seems like voodoo, I used to edit on Quantel gear, which used RAID 5 (similiar to 3), and over the years lost a few drives, but not ONCE lost data. Sold me on the concept. Anyway, the downside is you lose space on the array to the redundant data as well as some speed. In RAID 0, the is no parity, so you lose any drive, the entire array is toast. But it’s the fastest, and no space is lost. Unfortunately I forget the specifics of mode 5, other than I believe it’s very similiar to 3 in end result. Many people only load video on their arrays, so a total crash only means redigitizing. They prefer mode 0. But I decided to keep all my project directories on the array as well, so I’d have protection for all the ongoing artwork, 3D, effects, scripts, etc etc; so I use mode 3. Any way you go of course, when you add drives to the array, the entire kaboodle gets wiped.

Bob Woodhead / Atlanta
Quantel-Avid-FCP-3D-Crayola
G5 DP 2G, 10.3.4, 3.5GB RAM, FCP 4.5, Aja IO, Huge 320R [raid3]

[Michael Peele]

RAID 3 uses byte level striping with a dedicated parity drive (all recovery info on one disk).
RAID 5 uses block level striping with a distributed parity drive (recovery info spread across all disks).

Traditionally RAID 3 was used for video editing but RAID 5 works as well.

RAID 3 takes a very small perfomance hit if you lose a drive – i.e. you can keep working with a downed drive.
RAID 5 takes a moderate perfomance hit if you lose a drive and this may keep you from working.

Mike Peele

[Bob Woodhead]

Thanks Mike – that’s the best description I’ve ever heard.

[Michael Peele]

No problem, and thank you,
Mike 🙂