Please Explain The Benefits of Raid 0

[Hugh DiMauro]

I have been reading up on RAID 0 and Raid 1 and understand the risks but would like to better understand (in laymens terms, please) the benefits. I suspect Mr. Chan will respond to this since he is the resident expert.

Currently, I am back using Vegas 6 on a Dell Precision 670 Workstation, 64 bit O/S, dual Xeons with a 40 gig SATA system drive,

Two (2) 250 gig internal 7200 RPM IDE hard drives
One (1) 200 gig internal 7200 RPM SATA drive
Two (2) 120 gig external 7200 RPM IDE drives

I believe I have a built-in RAID controller. Should I set up my system with RAID 0 since I have the drives for it or should I just save the various components to different drives as I'm doing now?

OH, also, what are the benefits of capturing/editing/printing to tape uncompressed video? Is the picture quality better to the naked eye?

[Mike Teutsch]

Hugh,

All I can do is explain the very basics of it but maybe it will help. I considered going to Raid 0, and passed on it.

If you have three drive for instance, the processer writes to and reads from all three drives at once as necessary. For example you finish a nice big project and save it.......it is written not to one drive, but about one third to each available drive. This makes the process much faster, let's say one third the time is needed. This makes for a very fast computer for editing and processing.

HOWEVER, if you should have a drive go bad or fail, and you are unable to recover it, you loose all the info from all three drives. One third of your info is gone because of the drive failier and the other 2/3rds is no longer useful or avaliable either because none of it is whole or complete.

If you are willing to risk a failure, and or you back all of your data up regularly it may work great for you. If you do not want to take the risk, then operating system on one drive, video files on another, and audio on the last is fastest and safer.

As far as if you can use Raid 0 on your system, others will have to help. You may or may not be able to, as you basically have three different drives as I see it...... Mr. Chan? He'll correct what I have wrong.

Good luck, and now wait for an expert!

Mike

[Hugh DiMauro]

Then RAID isn't for me. I'll just keep all my stuff svaed to separate drives.

But gee... if my drive with the video clips goes bad, then aren't I still in the same boat?

[Jean-Philippe Archibald]

Hugh,

Yes, but with raid 0, you double the "chances" of a drive failure. Raid 0 is definitelly not a good option for any type of critical operation or persisting data. This is a well known topic for me (I'm a computer analysist by day). Raid 0 may be usefull to put some data on it temporarilly for cpu crunching, in the field of statistic for example. When keeping the data alive is critical, Raid 0 should be avoided and replaced by Raid 1 (data mirorring), Raid 10 (data mirorring + data stripping. require a minimum of 4 discs) or raid 5 (not as effective as raid 0, but the data of a dead disc can be recovered by a sophistical algorhitm analyzing the bit parity of the remaining discs. Require a minimum of 3 discs).

For video editting on personnal computer, where the number of discs that can be hooked to the computer is limited, Raid 0 is definitly not the right awnser. The risk is too high.

[George Ellis]

Actually, you do not double the chances for failure with RAID 0. Failure is calculated a might differently than that. You could move your mean chance of a failure from 10 years to 8 or even 5, but that does not double your chance. A failure will eventually occur, but it may not be in the computer's useful life or it may be another component.

The advantage of RAID 0 is that you can easily make a single drive volume from two physical drives using hardware (or software, but there are other methods using software it that is your only option.)

[Hugh DiMauro]

Thank you for all of your replies. I'll stick with good old fashioned no raid.

[Rob Lohman]

George: I *think* the line "double the chances" comes from if you loose one
drive you loose 'em both. So if you have two 250 GB drives in a raid 0 array
you can store 500 gb of data. If one drives goes down you loose the full 500
gb (if the array was fully filled) of data instead of "just" 250 gb.

p.s. for anyone wondering why, raid 0 does block interweaving. Let's say your
NTFS block size is 4 KB (for large files usually the larger the block size the better).
And a file has 4 blocks (ie, the file is somewhere between 12 and 16 KB large)
block 1 will be stored on disc 1, block 2 on disc 2, block 3 on disc 1 and block 4
on disc 2 (of course the exact pattern might be different, this is just an example).

This means that half your file is on drive 1 and the other half is on drive 2. This
is where the speed comes from. It can write and read simultanously from both
drives. However, if one drive fails you've lost half of your file. The other half
still exists, but is usually worthless without the lost half.

[Stephen Finton]

I'd only use RAID 0 for capturing HDV.

If doing SD, keep it simple. A single drive will suffice.

[Hugh DiMauro]

Thanks, Stephen. I will be using SDV for the time being.