Raided Hard drives, bad or good?
 

Is it bad to be working off a raided hard drive system, I've got 2 140 GB's running off a duel xeon processor set up, and 4 gigs of ram... the machine flys, but I've been reading about how I should store audio and video on separate drive as well as preview files..

S++t Happens!
 

We are running 12 - 146gig hardrives or 1.75 Terabytes in a Raid configuration (basically 2 drives) with no problems. Dual 3 gig processors and 3 gigs of RAM. Does that mean that we are safe forever?

Absolutley not!

Regardless of how you run, computers are computers are computers...end of story.

Take a look at our system at http://www.rbravo.com/vsu_equipment.htm

Just scroll down to the EDITING portion of the page.

Go for it and enjoy.

RB

Pat: define "bad" please.

first you have to define wich RAID you use.
the only raid that is safe is the MIRRORING of data from one disk to another. This gives no real performance improvement but if a drive fails, you can continue to work.
RAID configuration that simply merge several disk to give a bigger one offers no security at all. even worse if one disk fail, the good one becomes unusable.
If you need BOTH security and performance and have a lot of money you can look at raid 10 or 50.
RAID 50 is very safe because you can have several disk failing at the same time and still can work. The cost is heavy because you have the cost of raid5 (one disk lost on a set of disk) plus the cost of the raid 0 (all disks in the raid mirrored.).
Do not become paranoid about RAID. A simple mirror is already a huge improvement and if you got a third one to backup essential files against mistake (not failures) you already got a perfect system.

Depending on your NLE, you can restore your project by batch capturing off the source tapes. For this you need to backup your project files and/or EDLs.

I haven't heard of that offering useful performance gains if you're working with DV footage. I am assuming you are talking about a setup like:
OS on one hard drive
swap on another
program files on another
video/audio on big drives

Here is what we say on our recommended systems page:

Video Storage recommendations
With todays powerful processors, lightening fast memory, super 3D graphics cards and huge ATA hard drives you can capture, edit & playback single stream DV video with your system drive. That said, we still urge you to get a dedicated hard drive (7200 RPM or faster) for all your video clips. This will produce the best results - especially for video projects over 1 hour in length. If you are going to be using one of our Real-Time NLE solutions then we still recommend a VideoRAID, EIDE Raid or SCSI for best results.

We recommend Serial ATA (SATA) drives for NLE. While these drives do have a cost premium, the improved sustained data throughput is worth it. We also like the new cables which allow for better air flow inside your computer case. We have not yet had the chance to test any SATA Raid controllers, but we're confident that they will work great with our software based NLE solutions. RAIDs are great! For the best results set up a dedicated RAID 0 stripe for your video & media files. This will give you a huge capacity with the fastest possible sustained throughput for your editing.

RAID Warning! We do NOT recommend setting up your computer with a single RAID 0 array as your boot drive and video storage. This may actually give you poor performance for video editing. The constant reading and writing of small bits of data to the boot drive works against the need to read & write large continuous video files. Add in the overhead of the RAID controller and you get potential bottlenecks. For video editing you always want to have a dedicated drive or RAID array for your video files.

http://www.videoguys.com/system.htm

Gary

I have to say that I have not seen any hard evidence that makes an argument for RAID. Many people say that theoretically RAID is better, but theoretical things don't always translate to real world performance (and the theory may be wrong).

I did some testing on the difference hard drive speed makes. You can find my results + testing methodology over at
http://www.dvinfo.net/conf/showthrea...threadid=18784

I tested the effect of hard drive speed on rendering speed.

The bottom line from that particular test is that RAID is not worth the effort.

Things to watch out for are:
A- Testing methodology. I did not have an actual RAID to play with, but used a RAM disk instead (theoretically many times superior).
B- Whether the results apply to you. There are a few tasks where your renders are close to file copies, in which case RAID would make a difference. But in those cases, it's faster to have just a bunch of disks (render from one to the other).

Glen,

There are two good reasons to use RAID:
1. Protection against hard drive failure
2. Performance

It depends on the RAID level you use. I would think protecting against hard drive failure is always a benefit.

Well Glen, your results may be interesting, but have nothing to do with RAID if you did NOT use RAID in your test setup. :-)

FYI, even if you use a RAM disk, it doesn't mean that the data is always in memory. Don't know what your OS is, but Windows always uses virtual memory, which means what you think is in memory may be swapped out to disk.

A good RAID for performance and protection is RAID Level 3. For more info see
http://www.pcguide.com/ref/hdd/perf/...eLevel3-c.html
http://www.acnc.com/04_01_03.html

HTH.

JM, do you have a RAID3 set to play with?
Have you tried rendering to the drive? It might turn out to be slower since RAID3 has slow writes.

Glenn,

No, I don't have a RAID 3. But according to a number of sources, it is well suited to video editing. It is slower in small, random writes, but faster in large writes. See the second ref in my previous post.

RAID 0 should yield the best performance, but does not offer any protection against a HDD failure. Some RAID controllers are highly optimized for RAID 0 providing substantial improvements in performance.

Performance is becoming less and less of an issue with the very fast HDDs we have today like the Ultra133 and the SATA drives. Of course SCSI is even faster. I have not done any testing but I have seen several posts that NLE is constrained more by CPU and RAM than by today's HDDs.

Back to Pat's original question. Given that he has duel xeons and 4GB RAM, I wouldn't even worry about RAID from a performance perspective. But yes, I would put the OS and the video data on separate drives. If I did any RAID, it would be to put the OS on RAID 1 for protection.

Better to leave the OS non-raid imho. WD Raptor makes a great C drive.
Raid the capture/working drives. For mission critical- backup important files to another non raided drive or to dvd for small files.

Remember to do a backup of your C drive regardless...(I say to my lazy self also)

Hi,

Raid tests and reviews:

http://www.storagereview.com/articles/200406/20040625TCQ_1.html

http://www.anandtech.com/storage/showdoc.aspx?i=2101

Personally I have decided for a hardware raid 5 setup. Using the "Promise FastTrak S150SX4 4-port SATA RAID5" with 256mb onboard memory. The array will be in my server machine(serving my 2 client computers ). I'll have 4x250gb HDD which will give me 750gb raided storage ( 250gb is parity bits for safety ).

I'll connect the machines by Gigabit ethernet.

// Lazze \\

Those two links don't have benchmarks/tests really relevant to video editing. Except for anandtech, which tested game loading times (which is important when you're not editing video :D).

Things that do matter for video would be:
# of real-time streams. RAID does help here if you want lots of RT streams. For what you do you may never be bottlenecked by your hard drive.
Rendering times. The benefits from RAID is very questionable.
Exports. (Having seperate drives is faster however)
Other things you can think of that slow you down. i.e. stitching for Vegas network rendering- this may really benefit from RAID 0.

Hi,

Maybe they didn't measure NLE performance using stripe... but I seriously don't think that any NLE will render ( even using Netrender modules ) faster than 30mb/sec - and that will a standard new model HDD handle just fine.

RT streams - sure if you have several uncompressed streams you can gain from striping. In this scenario I'd go for a gigabit hooked up server for feeding the viewer-client - since network traffic using good NICS uses less CPU than reading from HDD

My option going for Raid 5 isn't all about speed - it's about Security AND speed. Using the promise controller with onboard parity bit CPU and 256mb cache-memory is IMHO the "most secured bang for the buck". You could do a nice Raid 5 array with 200gb disks which are really cheap here in sweden - You get a 8mb cache 200gb disk for about 130 USD.

Will be back later when I have some real bench values to display ( new server will arrive within 2 weeks )

Best regards,

Lazze

ps. U R right, gaming can be important...Doom III here I come! ds.