To RAID or not to RAID...
 

I recently purchased one of the Western Digital 80Gig hard drives with 8MB of cache. I initially bought it to be a stand alone video/audio drive, seperate from my operating system/application drive. I'm evaluating a couple versions of editing software before I decide what to buy (Avid, Premier, etc). The more I read, the more I wonder, before i go too far, if I should buy another drive and a RAID controller and run a RAID 0 array with 80gig drives.

What will I gain by running RAID performance wise? What about the failure rate and losing all data? I'm generally more looking for opinions and experiences. I'm running an AMD Athlon XP 1800+, with 512MB of DDR333, and ATI Radeon 8500, and Maxtor DX 60GB system drive, and now the newly added Western digital file drive.

I recently read an article that really scared me about losing my data if a RAID drive crashed. But at the same time, if my file drive crashes, I'm just as screwed. The more drives, the more probability for failure right?

Thanks,
Mike

Yes and no. There's lots of places that you can go to read about RAID modes in general, but to summarize (and oversimplify): RAID0 gives you double the performance, while risking either of two drives going out and ruining your data. RAID1 is sort of the opposite, it mirrors two drives, so you get single drive performance, but if one drive goes out you have a second with full data integrity. Most IDE RAID controllers also offer RAID0+1, which is 4 drives, mirrored and striped. So you get twice the capacity of one drive, twice the speed of one drive, and twice the backup. There's also RAID5, but that scheme is mostly reserved for bigger SCSI arrays, and is only worthwhile with 5 or more drives.

What you choose to use is a balance of personal paranoia, personal need for speed, and personal checkbook.

That is correct, however you can run raid 5 starting from 3 drives.
With 3 drives you get extra capacity (roughly the size of 2 drives)
and one extra drive that stores error correction information to
recover if one drive should fail.

There are two ways you can do RAID, hardware and software
(you need Windows 2000 Server for this to work). I would not
go with Raid 0. Although you will increase in data throughput
it will never double your speed. And if you loose one drive you
will loose both. Also for DV you will not neet a RAID array. If
you have current 7200rpm drive on a ATA100/133 (UDMA 4-6)
it will definitely be fast enough.

If you infest in two or more harddrives I would either chain
them together to get one large harddrive (you can do this with
most RAID hardware cards or you can do it in Windows 2000/XP
when you upgrade to a Dynamic disk -> not sure if this is server
only as well). Or just use one disk for all your input files and the
other for your projects/output (that's they way I have it setup
at the moment). Or you can go with RAID 1 (mirroring), which
you can also do both in hardware & software, for exta safety.

I think my next setup will feature the following:

- one harddrive for my OS and applications, with following partitions: OS (and programs), swap & misc (for downloading/burning etc.)
- one harddrive for my incoming footage, with following partitions: projects (for all project related footage) & misc (for all other footage)
- one harddrive for project data, with following partitions: project & output (final rendering etc.)

If money allows I will put mirror that last harddisk. If I loose a
project whilst working on it would be a disaster. Original footage
can be re-captured from tape (which I keep!) and the same go's
for my OS & application drive. I perhaps might get a DVD burner
instead though and backup my project on DVD every now and
then. Still thinking about that.

Just my two cents and ideas...

If all you are editing is DV, you're performance gain will not been much. DV, at 4mb per second is not pushing the limit of a single drive by any means. It may speed up rendering, if your plans call for a lot of it. But overall, the extra expense doesn't translate to real world (editing DV) performance increases. If you're doing HD, that's a different matter.

While the DV signal of 3.7MB/s is not a big tax on the hard drive, if you are playing several streams at once it adds up quickly because you are requesting data from several different sectors of the drive at once.
I have 4 drives in my machine, a boot drive (system and apps), a backup boot drive which is a copy of my main boot (NOT a mirror, If you mirror a drive, whatever corrupted material hits your primary drive automatically gets thrown onto the mirror also, not good) the backup also holds a copy of my project files as backups. The other 2 are in a ATA133 RAID stripe configuration (hardware). If for some reason I lose the stripe set (which I have when I used IBM DeathStars) I keep my logs backed up in several places (including Zip disk) so with FCP3 (sorry, I am on a Mac) I can just launch the backup project fie and capture the data exactly the same way to replace it. All I'm out is the re-capture time. All of my edits are saved and I'm back at work.
I noticed a big difference in speed when I started using the RAID. Video never stutters, drops, hangs and renders faster when I need to. Sure a single drive would work but the RAID is definitely faster. My RAID transfer speed is usually between 59-63MB/s whereas my single drive speed is about 32MB/s, and these are all ATA133 Maxtor fluid bearing drives.

I think it's a good idea, but then, that's me.

I don't think it is a waste of money at all. But I think you'll get more bang for your buck if max out your ram. If you've got extra money after that, get a RAID.

Not sure if there are any benchmarks out there for this, but I was under the impression that folks with real time hardware cards would benefit from increased throughput of RAID 0.

IDE RAID really only for Redundancy...not much performance gain.

SCSI is alot better, with Disconnect and Reconnect, Tagged Command Queuing...etc. IDE device have to wait for the whole operation to be completed before it will releases the bus for other transfer....SCSI don't need to with DIS/REC.

My 2 cents worth.

Alan, if you have a good new IDE RAID card it will increase your
performance. And with good cards I doubt other devices will
have to wait. And if you only have two devices you can but them
on a seperate bus. My Promise Ultra133 card (no RAID, but they
do have them in raid) can even mix different IDE protocols and
speeds without any of them getting in trouble on the same bus
(which was previously impossible for IDE)... so....

Tom's Hardware has done a pretty extensive article series on IDE and RAID. Here's some links:

For the executive summary, Benchmarks:
http://www6.tomshardware.com/storage...l#test_results

Part 1 on IDE: Basics and Technology:
http://www6.tomshardware.com/storage...806/index.html

Part 2: Performance and Data Security With RAID:
http://www6.tomshardware.com/storage...813/index.html

Part 3: Using RAID:
http://www6.tomshardware.com/storage...830/index.html

DV editing will not really tax your drives, as the capture is firewire limtied and rendering is usually CPU/RAM limited. The real question is SPACE. How much space do you want to use for video at 13GB per hour of video. Have a drive for capture and one to render to is nice or one hugh drive is nice. I wanted large space to have multiple projects on compute rat once so I have 6 drives, 2 x 40GB RAID 0 for OS and apps, then 2 x 80GB RAId 0 for capturing and then 2 x 80GB for rendering and final projects that need to be burned, etc. I used 80GB becasue 120GB was too expensive last year so I raided. If I were doing it today I would just get 120GB or 200GB drives and skip the RAID, you really don't gain much REAL WORLD performance and average latency can actually increase. The WD 8MB drives are great I would get a second just for the space and skip the RAID. My next system I am looking at going 3 drives, 1 80GB WD8MB, and then 2 200GB WD 8MB drives no raid!

"DV editing will not really tax your drives, as the capture is firewire limtied and rendering is usually CPU/RAM limited. The real question is SPACE."

Well, as I said above, this view neglects the demands of real-time editing hardware when accessing more than one stream at a time, as with real time picture-in-picture, or picture-in-picture-in-...^n

In the ultimate discourse of things Real Time Effects may be hindered by the performance limitations of a single drive. However, the original post concerns the use of AVID or Premiere software and neither uses RT Effects at the DV level. While Analog Video or HD Video would benefit (and RT Streams) RAID usage with DV may not be worth the risk. The added cost of two additional drives (and necessary controller) would only give him marginal performance increases for DV. He would more likely benefit more from additional RAM and at a more modest total expense. The RAM increase would give him more performance per dollar spent.

>If you're doing HD, that's a different matter.

Isn't HD still a 25 MBit MPEG2 stream ?

He was talking about the serious HD work, which is running at
a lot higher rate than 25 mbps HDV is using. It's probably more
running along the lines of 250 mbps.