RAID 0 organization - Can someone explain this for me?

[John Hewat]

I'm going to be editing Z1 footage in Premiere Pro and I keep seeing "2 drives organised as RAID 0" as recommended specs.

I am about to build an editing PC and was only going to purchase one 160GB System drive and one 250GB Video Storage drive.

Should these two drives be organised in RAID 0 or would that only apply if I bought a pair of 250GB video storage drives?

Secondly, I am going to build the computer myself and have no idea how to go about setting up this "RAID 0" - is it easy/difficult/complex?

What are the steps involved? I don't even know if it's a hardware configuration or a BIOS setting or what...

I'd love some help here.

Thanks,
-- John.

[Ash Greyson]

RAID 0 is a nightmare waiting to happen... you lose 1 drive... you lose them all. I would look to a more expensive RAID 5 solution or make sure you back up your EDLs and batch lists DAILY and your RAID 0 weekly...




ash =o)

[Graham Hickling]

The usual recommendation is to have your operating system and program files on a non-RAID drive, and then set up a matched pair of drives as a RAID disk dedicated to your video and audio files. This reduces the amount of drive head movement needed, and also helps keep the video drive unfragmented.

You CAN have just a RAID drive with both program and video files on it, however the performance boost won't be as noticeable. Disk drives are so cheap that I'd encourage you to go the separate route.

RAID 0 is considered more susceptible to failure because if either drive fails you loose all the data. Whether this is a major consideration to you will depend on how critical losing the data would be. For me its a non-issue because I store the raw footage and completed edits on DVD, so the worst-case is losing a day or two of editing effort.

RAID needs hardware support, either from your motherboard or - if that's lacking - from a separate RAID controller card that you plug in to the motherboard. Eitherway, there will be a small RAID setup program supplied that you fire up and it will step you through the process.

Note that the two drives in RAID array should be the same speed (e.g. 7200 rpm), and preferably the same brand. If they differ in size (e.g. 120GB and 200GB) then your RAID will only be 2x the smaller drive (e.g. 240GB) with the remaining space on the larger drive being wasted.

[Keith Wakeham]

Windows 2000 and windows XP can create software raids which have nearly identical performance to the cheap raid cards or onboard raids because these are just software devices too, not hardware driven. A Hardware raid card is expensive by comparison and normally requires its own ram on the card.

I don't know how you work but everyone I work with here uses tapes as a WORM device. Write Once, Read Many.

So the general config is like stated above. A seperate boot disk and two or more drives in raid 0. Usually this config isn't a problem and is similar to what i've seen with the avid symphony setup. The reason most people don't see it as a problem as the discs are only temp video storage. The log their tapes, do an edit, and delete everything pertaining to that edit from the drive after they do their output. The project is saved to the main drive and when ever anyone needs something changed they just do a batch capture.

If the drives are being used to store FX work look at a Raid 1 or Raid 10 or Raid 5 setup. These will provide some security for you work then

[John Hewat]

Thanks everybody - this clears things up a little.

But, what if I only want a single 250GB video storage drive?

Surely having two of them in any RAID configuration only speeds up transfers between those two drives, right?

Having just one drive (plus the 160GB system drive) can't be slower than having two drives in RAID can it?

Now, that said, I may get two 250GB storage drives, and my soon-to-be motherboard (the ASUS A8N SLI Premium) does support all sorts of RAID arrays. Here's what I've found out about the board:

ASUS has also included the Silicon Image Sil3114R controller. The Silicon Image Sil3114R controller offers four additional SATA interfaces and allows RAID 0, 1, 10, JBOD, and a RAID software patch to support RAID 5.

But I don't know what any of them are or which is better. If RAID 0 isn't too safe but RAID 5 is, what is the difference exactly? And what are all these other ones?

All in all, am I right in assuming that I don't need to actually purchase anything else to set up the RAID in any of those configurations? It's all program based? And hopefully it's all easy???

And this talk of losing one drive = losing both drives; is your hard drive more likely to disappear in one of these RAID setups? I've never had HDD problems on any of my computers in the past 10 years.

Thanks again everyone,
-- John.

[Steve Crisdale]

Originally Posted by John Hewat

Thanks everybody - this clears things up a little.

But, what if I only want a single 250GB video storage drive?

Surely having two of them in any RAID configuration only speeds up transfers between those two drives, right?

Having just one drive (plus the 160GB system drive) can't be slower than having two drives in RAID can it?

Now, that said, I may get two 250GB storage drives, and my soon-to-be motherboard (the ASUS A8N SLI Premium) does support all sorts of RAID arrays. Here's what I've found out about the board:



But I don't know what any of them are or which is better. If RAID 0 isn't too safe but RAID 5 is, what is the difference exactly? And what are all these other ones?

All in all, am I right in assuming that I don't need to actually purchase anything else to set up the RAID in any of those configurations? It's all program based? And hopefully it's all easy???

And this talk of losing one drive = losing both drives; is your hard drive more likely to disappear in one of these RAID setups? I've never had HDD problems on any of my computers in the past 10 years.

Thanks again everyone,
-- John.

I made a comittment to myself that I was done offering any advice, or help of any sort to anyone anymore...

Like a New Year's resolution, I just can't stop.

RAID arrays will nearly always be faster than a single drive (unless there's something seriously wrong!!) because the data is striped to both drives - meaning that read and write processes are run simultaneously (or close enough too) between both (generally 2 drives in RAID-0) drives.

The system "sees" the RAID array of disks as a single drive however. RAID arrays MUST have more than one hard disk.

2 hard disks can be set up as RAID-0 which does not have any redundancy. Redundancy is the ability to swap out a drive that may have failed without loss of data. To achieve redundancy, you'll need at least three hard drives in the RAID array. RAID-5 is the preffered mode for RAID with redundancy.

Everything else that's already been mentioned is worth noting. Namely same brand, speed and size will reduce likelihood of failures in any RAID componentry.

I'm running 2 X 120Gig 7,200 drives in a RAID-0 for all my video files. It's been chugging away happily for nearly 24 months without any sign of failure.
A single seperate 120Gig SATA drive on it's own SATA controller, has the OS, program and other graphics files, as well as a Permanent Swap File - rather than the usual "let Windows choose" rubbish. A permanent swap file won't require frequent defraging, and because it's permanent, it's not constantly being enlarged or shrunk when Windows decides to do so. It won't add lot's of speed, but it can make some processes "snappier".

If you decide to go RAID-5, be aware that there is a small performance hit, because the 3rd drive is used to store a version of the data on the other drives, and will usually wait for an opportunity when the system is idle to do so... but the system may not necessarily be idle, and the result will look like a slow-down of the system while the RAID does it's re-compile.

Generally only data-sensitive institutions (financial institutions and the like) go for RAID-5, while most performance junkies go for RAID-0.

The board you are looking at purchasing seems to be fine for setting up a nice fast SATA RAID-0 array of 2 fast 7,200rpm or better disks of the same size and brand.

BTW: I hope you aren't considering just putting 2 disks together in a RAID array... and that's the only hard drive sub-system on your machine?

[John Rofrano]

John, I just built a PC around the ASUS A8N-SLI Premium motherboard (my complete specs are on the PC Equipment page of my web site) and I’m using two 250GB WD drives in a RAID 0 for capture. This is the first time I’ve used a RAID 0 and there is definitely a performance boost. It wasn’t hard to set up. When you load XP you will have to hit F6 to have it prompt you for a drivers diskette because XP doesn’t support SATA natively and you want the SATA RAID drivers loaded with the OS. The CD that comes with the motherboard will have the drivers on it and show you how to make the diskette. The utility to set up the RAID is built into the motherboard BIOS and the directions that came with it were very easy to follow. I set up the RAID 0 before I loaded the OS and everything went smooth.

If you only have one capture drive then you can’t make a RAID anyway. You need at last two identical drives so don’t worry about it.

All the talk about RAID 0 being a nightmare waiting to happen is a little exaggerated. Look at it this way, if you buy a 500GB hard drive and it fails you loose all your data anyway. So what’s the difference if you buy two 250GB hard drives and put them in a RAID 0? I understand that you statistically increase your change of failure because now there are two drives, but if you kept them separate, you would still loose all the data on the failed drive anyway. A drive failure, is a drive failure, is a drive failure. Whether it’s one 500GB drive or two 250GB drives is still the same loss. Backup your data even of you don’t have a RAID 0. People should not be afraid of RAID 0. It is not a nightmare waiting to happen anymore than any drive is an accident waiting to happen if you don’t backup your data! The performance boost is well worth it (knock on wood). ;-)

~jr

[Graham Hickling]

Just by way of comparison .... I have a P4 2.8GHz on an ASUS P4S800D m'board with two Hitachi 80GB 7200rpm SATA drives in RAID0, plus a Seagate 160GB 7200rpm IDE drive as an additional data drive.

SiSoft Sandra reports a benchmark throughput of 63MB/sec for the RAID disks versus 34MB/sec for the Seagate.

[Glenn Chan]

John, RAID 0 does increase your chance of losing data (or it doubles your data loss, depending on how you want to look at it).

Suppose that a drive has a 10% chance of failing (totally arbitrary number- actual rate is likely much less). Also suppose that each drive holds 10GB of data.

No RAID:
The chance of either drive failing is close to 20%. When that happens, you lose 10GB of data. On average, you lose 2GB of data.

RAID:
The chance of the entire RAID failing is close to 20%. When the RAID fails, you lose 20GB of data. On average, you lose about 4GB of data.

Now if you wanted to be more accurate, you could consider the case that both drives fail. But it only makes a very small difference to calculate things more accurately.

2- My own tests show that RAID doesn't really give a meaningful performance increase. Basically, it doesn't affect your render speed unless your render is like a file copy.
http://www.dvinfo.net/conf/showthrea...id=18784<br />

And really, it's render time that takes wastes the most of your time. Not waiting for windows or programs to load. Even in that case, most real-world benchmarks show only a ~10% increase in speed from RAID. In some cases, RAID is even slower than no RAID. Video editing can be like this if you manually wrangle your renders.

Reading from one drive and writing to another is the fastest, followed by RAID 0, following by reading and writing to an individual drive.

[Graham Hickling]

> most real-world benchmarks show only a ~10% increase in speed from RAID. In some cases, RAID is even slower than no RAID

Obviously, RAID doesnt speed up intensive rendering, because that is CPU rather than disk limited. But for most everything else I do - booting up, file transfers etc etc - it has made my system much more responsive.

And to the extent that I live (I think) in the real world, I sure can't say I noticed anything running slower!!!

[Jim Michael]

Originally Posted by Steve Crisdale

2 hard disks can be set up as RAID-0 which does not have any redundancy. Redundancy is the ability to swap out a drive that may have failed without loss of data. To achieve redundancy, you'll need at least three hard drives in the RAID array. RAID-5 is the preffered mode for RAID with redundancy.

There is another option RAID 1 which permits mirroring instead of striping with 2 drives.

[John Hewat]

Originally Posted by John Rofrano

A drive failure, is a drive failure, is a drive failure...

Well I bought the componenets of my new computer but I'm paying a technicial to put it together for me as I didn't trust myself to do it.

I told the guy I want RAID 0 on the two 250Gb hard drives (there's also a single system drive).

He said "Ok, pal, do you want to keep them as separate drives with a partition or make them one big single drive?"

He explained that the performance would be identical either way but that by partitioning them, whilst in RAID 0, they would be separate and therefore safer.


Does this sound right to anyone?

[Steve Crisdale]

Originally Posted by John Hewat

Well I bought the componenets of my new computer but I'm paying a technicial to put it together for me as I didn't trust myself to do it.

I told the guy I want RAID 0 on the two 250Gb hard drives (there's also a single system drive).

He said "Ok, pal, do you want to keep them as separate drives with a partition or make them one big single drive?"

He explained that the performance would be identical either way but that by partitioning them, whilst in RAID 0, they would be separate and therefore safer.


Does this sound right to anyone?

Never read or heard that in the time that I've researched into or used RAID arrays. Doesn't mean it's not possible.

Personally, I figure that partitioning is a hangover from the days when our Hard Disk space was so limited and OS's didn't support such large disk sizes, that partitioning was the most efficient way to use every scrap of available hard disk space... so why bother partitioning when large disk sizes are now supported.

If it was me... and not you making the decision - I'd make it one nice big RAID-0 array, no partitioning.

I'm not you - and you know what will make you feel the most comfortable. You gotta make the call on this.

[Graham Hickling]

If anyone wants to read a bit more on the WindowsXP-Pro software RAID approach mentioned earlier in this thread, here's a link:

http://www.techimo.com/articles/index.pl?photo=149

[Glenn Chan]

John: Windows can probably do drive spanning, where it puts both drives into one large partition.

It allows files greater than however big your hard drive is. And it does not suck CPU cycles for RAID 0 calculations. The partition will be as fast as a single drive.

Drive spanning is not the same as RAID 0.