New Mac PRO Internal Raid

David S. said:
For what's it's worth, I've also edited off a USB2 bus powered TravelStar 100 GB/7200 rpm using a MacBook, not Pro.

Only did 720/24pN, but it never dropped a frame
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I've also edited 720/24pn material on a FW400 bus powered 5400rpm drive but the point is the guy has a MacPro with spare internal drive bays and he has already bought the drives, so I dont see any logic in questioning why he would want to stripe them as a raid? It has nothing to do with being on a budget, in fact buying 2 bare 250gb sata drives is a lot cheaper (less than 1/2) the cost of a single 500gb FW800 G-drive and striping them as a raid 0 will give better performance as well.
 
I didn't think I was questioning his logic, but rather just asking a question about why he's editing from a RAID and contributing information about all our experiences. May be he wasn't aware of it or may be not.

The "logic" behind it is that other people also read these threads and may learn from all our experiences.

That's what these boards are about.
 
Drives of the same generation that are larger in capacity tend to be faster even at the same rotational speed because of the data density on the platters. There is less surface area for the data to be recorded to and read from, so there is less distance for the heads to travel to retrieve the same data. That said, older larger drives will not outperform newer smaller drives because of advances in drive tech, and the number of platters on the drive. Check out the review of the new hitachi 1terabyte drive at anandtech, it's a 7200 RPM drive, but matches the fastest SATA drive of the previous generation, a 150Gig WD Raptor 10,000 RPM drive.
 
BenB said:
The SATA drives internally to a Mac are even faster. With them, I honestly don't see the need for RAID in most editing shops.
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This discussion has focused on speed, but RAIDs can be used for redundancy too. I suggest using RAID 1 to protect against hard drive failure. Personally, I'm using a RAID 10 in an external eSATA enclosure.
--Jeremy
 
In all my years working as an IT Engineer I've seen tons of RAID systems fail and tons of data lost. RAID's redundancy was designed for hot swap of drives, not as an offical, reliable back up method. If you're relying on your RAID's redundancy as a back up, well, you're still flipping a coin. RAID's reduncancy is pretty stable, but not bullet proof.

To ensure the safety of your data, you really do need to do an honest back up.
 
BenB said:
To ensure the safety of your data, you really do need to do an honest back up.
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Yeah, I do that too using project-specific hard drives that I take off site.

Here's a question I haven't found an answer to: Since I'm using RAID 10, I'm not as concerned about a hard drive failure, but have you ever heard of RAID 0 striping getting corrupted and losing data that way? I've read that corruption is a concern with RAID levels 3 and 5, but I've never heard of this being a problem with level 0.
 
Standard RAID levels

A quick summary of the most commonly used RAID levels:
  • RAID 0: Striped Set (2 disk minimum) without parity: provides improved performance and additional storage but no fault tolerance from disk errors or disk failure. Any disk failure destroys the array, and is twice as likely to fail.
  • RAID 1: Mirrored Set (2 disks minimum, and usually exactly 2) without parity: provides fault tolerance from disk errors and single disk failure. Increased read performance occurs when using a multi-threaded operating system that supports split seeks, very small performance reduction when writing. Array continues to operate with one failed drive.
  • RAID 0+1: Striped Set + Mirrored Set (4 disk minimum; Even number of disks) provides fault tolerance and improved performance but increases complexity. Array continues to operate with one failed drive. The key difference from RAID 1+0 is that RAID 0+1 creates a second striped set to mirror a primary striped set.
  • RAID 1+0: Mirrored Set + Striped Set (4 disk minimum; Even number of disks) provides fault tolerance and improved performance but increases complexity. Array continues to operate with one failed drive. The key difference from RAID 0+1 is that RAID 1+0 creates a striped set from a series of mirrored drives.
  • RAID 3/4: Striped Set (3 disk minimum) with Dedicated Parity: Provides improved performance and fault tolerance, no performance penalty. Depending upon the implementation, dedicated parity could allow the parity drive to fail and operation will continue without parity.
  • RAID 5: Striped Set (3 disk minimum) with Distributed Parity: Distributed parity requires all but one drive to be present to operate; drive failure requires replacement, but the array is not destroyed by a single drive failure. Upon drive failure, any subsequent reads can be calculated from the distributed parity such that the drive failure is masked from the end user. The array will have data loss in the event of a second drive failure and is vulnerable until the data that was on the failed drive is rebuilt onto a replacement drive.
  • RAID 6: Striped Set (4 disk minimum) with Dual Distributed Parity: Provides fault tolerance from two drive failures; array continues to operate with up to two failed drives. This makes larger RAID groups more practical. This is becoming a popular choice for SATA drives as they approach 1 Terabyte in size. This is because the single parity RAID levels are vulnerable to data loss until the failed drive is rebuilt. The larger the drive, the longer the rebuild will take. With dual parity, it gives the array time to rebuild onto a large drive with the ability to sustain another drive failure.
Nested RAID levels

Many storage controllers allow RAID levels to be nested. That is, one RAID can use another as its basic element, instead of using physical drives. It is instructive to think of these arrays as layered on top of each other, with physical drives at the bottom.
Common nested RAID levels:
  • RAID 01: A mirror of stripes
  • RAID 10: A stripe of mirrors
  • RAID 50: A stripe across distributed parity RAID systems
  • RAID 51: A mirror striped set with distributed parity (some manufacturers label this as RAID 53)
Nested RAIDs are usually signified by joining the numbers indicating the RAID levels into a single number, sometimes with a '+' in between. For example, RAID 10 (or RAID 1+0) conceptually consists of multiple level 1 arrays stored on physical drives with a level 0 array on top, striped over the level 1 arrays. In the case of RAID 0+1, it is most often called RAID 0+1 as opposed to RAID 01 to avoid confusion with RAID 1. However, when the top array is a RAID 0 (such as in RAID 10 and RAID 50), most vendors choose to omit the '+', though RAID 5+0 is more informative.
 
Ben,
That looks like a good RAID level summary. Not sure if it was in response to my question. I was saying I have RAID 10, or 1+0 if you prefer. Most people talk about drive failure as the primary mode of losing data. (e.g. like in your post) but another failure mode is corrupt parity (RAID 3 or 5) or corrupt striping (RAID 0). I'm wondering if anyone knows how common corrupt striping is using Mac's OSX Disk Utility as the RAID controller.
--Jeremy
 
SoftRaid is the bees-knees for software RAID 0 and 1 on a Mac.
RocketRAID to a SATA setup is a great hardware RAID5 solution.Been using that with 8-Drives in 2 FirmTek enclosures on a QuadG5 for the last year with zero issues.
440MB/s for 2K playback. Lovely...
 
I was hoping to use SoftRaid because it has better error checking than Disk Utility, but the current version doesn't support RAID 1+0.
 
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