Should I use raid 0? What are the cons? 6

[Atomicboy22]

Hello. I just bought 2 160G WD hdd's on sale. I'm going to replace my current 120G with them, and I bought 2 in hopes of trying out raid 0. I want as much performance as possible

I'm just trying to find out more info on how secure this array actually is though. In other words, I don't wnat to set this up to only have a bad sector on one drive crop up in a month and the whole array becomes unuseable due to this. I have been reading as much as I can about raid 0, but no one really addresses the issue of how stable it is. I know that if one drive fails, the whole array does, but how is the array effected by bbad sectors? What else can happen? How stable is a raid 0 array? Should I bother, or should I just use both drives as a regular IDE master/slave and not worry about raid?

I was surprised to see how little most people actually know about raid, and how uncommon it actually is. From what I read on it, it seems like the next best thing, but there must be something that is preventing people from using it, and this is what I'm looking for.

Please help, thanks a lot

 

[comtec17]

Great site on RAID levels. A RAID 0 array provides no fault tollerance. It is only ment to combine 2 hard drives into a singe partition (Striping). If a block or sector of a drive goes bad, that block is not used, or if any data in the block/sector goes bad, so does the data. You will lose majority of your work if not all if 1 drive goes bad. This is true since you do not know where on the stripe the data is being placed.

 

[IslandCustom]

Being cautious, I use RAID 1. RAID 1 mirrors two drives. If one drive fails, the other continues to run. You can then replace the failed drive and rebuild the array by mirroring to the new drive. Quite fault tolerant, but that tolerance comes at a price -- two 160GB drives is equal to 160GB, not 320GB. Of course, you can have RAID 0's speed with RAID 1's fault tolerance (RAID 0+1), but you'll need more than two drives.

 

[comtec17]

Forgot to post the site

http://www.acnc.com/raid.html

 

[lesgray]

comtec17 is right on the money. Raid 0 is made for speed. You read/write performance will be great, but your data will be at risk. If anything goes wrong with a drive, then POOF, all your data will be gone. Stability on a raid 0 is great, so long as a drive doesn't fail. ANY failure and you start all over again.

IslandCustom is correct as well: Raid 0 provides you with redundancy at the cost 1/2 your drive space. Also, unless you are using a raid card (onboard or otherwise), i.e. if you are doing a software raid within WIndows 2000/XP, your read/write speeds will be slower than without the raid.

Raid 0+1 works nicely, but you'll need 4 drives, what you'll have is two Raid 0 setups, one mirroring the other. Speed is fairly reasonable and redundancy is good. If a drive fails, you replace it and create a new Raid 0, then rebuild the mirror. Total drive space is still 1/2 of your avialable space.

If you can afford it, and your raid card supports it, Raid 5 is probably the best bet. You need 3 drives minimum, redundancy is spead out amongst the three drives, so in the case of a drive failure, you simply replace the drive and rebuild the raid 5. Total drive space is xn-n where x is the number of drives and n is the size of an individual drive. In your case, using 160GB drives and the minimum drives required, which would be 3, then your total drive space would be 3x160GB-160GB, which would be 320GB. Raid 5 gives you the best fault tolerance/speed combination. If you want a first rate Raid 5 card the Promise FastTrak SX4000, is relatively cheap (about $140) and works flawlessly - maxes out at 4 drives though.

You can also setup a raid 5 without a raid card within Windows 2000 Server and WIndows 2003 Server. The software raid 5 works pretty well. I have been running a Windows 2000 server for about 3 years with 7x23GB SCSI drives in a raid 5 configuration and I have found the speed to be very acceptable. I have had two drives fail during this period and both times the raid rebuilt itselt flawlessly after I replaced the failed drive. The server remained in use during the rebuild, although of course speeds were very much affected.

There is also something new called Raid 1.5, used on some motherboards, particularly DFI which is a combination of Raid 0 and Raid 1, providing redundancy and speed using only 2 drives. However unless you have one of these boards you can't use it. If you do, let me know and I can discuss that with you, because it does work very well.

Hope this helps;


Les Gray

http://www.creartec.com

 

[SYAR2003]

Hey Les!
Every one is stating that Raid 0 is a risk.
If we compare an IDE setup with one disk .
And a Raid 0 setup as "one array disk" utilizing two disks .
Is there really a difference in the possibility to loose data?

It seems to me that everybody think that raid controllers
are more insecure than ide controllers.

We are talking about personal computers ,not servers.
People with a home pc ,that may want to switch from
one or more disk at ide over to a raid solution .
I think the comparsion shold be between that two options
with the focus on identical file/disk security.
The increaded security with other sets than a raid 0 setup
seen as a bonus for them that want to icrease security
compared to old setup utilized with ide.


Any insights..

syar

 

[lesgray]

Quote
"Hey Les!
Every one is stating that Raid 0 is a risk.
If we compare an IDE setup with one disk .
And a Raid 0 setup as "one array disk" utilizing two disks .
Is there really a difference in the possibility to loose data?"

Hi SYAR2003:

No, there isn't any difference on the possibility of losing data, but for some reason most people think that Raid of any sort is more secure. It is the amount of data lost that makes the difference. Raid 0, of course is not terribly secure (no more than a single drive is secure), and that is what bears repeating.

This of couse assumes that the drives sizes are of equal size, say a raid 0 of 2x80GB and an ide 160GB drive. If you setup two 160GB drives as separate drives, ,if one goes bad, then you have only lost only 1/2 your data, whereas with a Raid 0 of 320GB (2x160GB Drives) you lose all your data - twice as much.

There is certainly more file security with a Raid 1 setup - if a drive fails then you simply replace it, rebuild your mirror and voila, everything is as before - no data loss. The caveat, of course is that you only have 1/2 the total drive space available and speed is down from what you can expect from a single drive or a raid 0.

It seemed to me that Atomicboy22's original question was regarding data security on a Raid 0, which is why I answered the way I did. Raid 0 is inherently insecure for data. It is built for speed, with no regard for data loss. Usually it is used in situations where speed is required and where data loss is an acceptable issue - i.e. the data is replaceable, but speed is not.

Situation 1 - say you are a graphics person. You are working in photoshop. You have images you wish to work on that you already have backed up to another format, say CDs. Photoshop is ram intensive and harddrive intensive program. It will benefit from a Raid 0 setup particularly in its use of a scratch disk. If you lose a drive in the raid 0, well, you current thing you are working on is gone, but if you save on a regular basis to another drive or media, then you have only lost what you are working on at that moment. You replace your failed drive, setup your Raid 0 again, paste on your operating system/program image file, reboot and away you go again. We are assuming here, that the additional gear to make all this happen is available to our imaginary graphics dude.

Situation 2 - a dedicated gamer with any of the newer 3D games. The use of the hard drive is intensive by these games and certainly a raid 0 setup for the operating system and the game program files will improve performance. Other than the game saves, the gamer doesn't really care about his data - all they want is better performance. Raid 0 will help. The operating system can always be reloaded and so can the game itself. So long as the game saves are backed up to another media, the gamer is good to go. This gamer desn't care about data, only about frame rates and winning. His raid 0 goes down, he replaces the dead drive, whines a lot about the time lost in which he could have been playing the game, reloads the operating system and is programs (from an image if this is the second time they've lost everything) and away they go again.

Situation 3 - informed home/business user. They understand and have read about Raid 0 and 1. They understand the value and necessity of backing up often and what needs to be backed up including things like email and favorites. They want more speed out of their computer and understand that the raid 0 will improve their speed, but at the cost of all their data if it a single drive fails. They enquire about backup solutions and use them. They are impressed with the performance increase they get from the Raid 0 and swear by it. Until a drive fails. Although they are completely backed up, they hate spending all that time to rebuild their system. Most of them, will not setup a raid 0 again.

Situation 4 - typical home/business user. This person has 2 x 120Gb drives, a cdr-w type drive and a decent home PC and only a vague idea of what backing up means (to a lot of them, this means putting their resume/accounting data on a floppy - I kid you not). They've heard about Raid and how fast Raid 0 is. They have the necessary components - two identical drives and a motherboard with raid on board. They setup the raid 0, load the operating system and their programs, hopefully remember to do all the Windows updates and mavel at the newfound speed. They sing the praises of raid 0, religiously backup their resume/accounting data, and are happy. Until the day a drive fails. Then everything is gone and they don't understand. They had a raid setup. It was supposed to be secure and fast. What happened?

There are of course many other situations other than these, however I have personally seen all of the four above, including situation 4 several times.

Raid 1 - mirroring is an entirely different issue. Very secure and works great - BUT you lose 1/2 your drive space and your performance is somewhat reduced depending on what raid solution your are using (onboard, raid card, software raid). Your files are constantly backed up
and your only worry for file security is what happens if someone breaks in and steals the computer or if there is a fire and the whole kit melts.

Hope this helps and is not just a meaningless ramble;


Les Gray

http://www.creartec.com

 

[lesgray]

Error on my first post:

Just noticed that the 2nd paragraph should read:

"IslandCustom is correct as well: Raid 1 provides you with redundancy at the cost 1/2 your drive space. Also, unless you are using a raid card (onboard or otherwise), i.e. if you are doing a software raid within WIndows 2000/XP, your read/write speeds will be slower than without the raid."

I inadvertently said raid 0, when I meant to be discussing raid 1.

Sorry if i confused anyone;

Les Gray

http://www.creartec.com

 

[Atomicboy22]

Hello. You have been very helpfull les.

I do intend to use this for speed, mostly for games, and video editing, so that is why raid 0 is for me. I was concerned about the stability of raid 0 though, but it has been brought up that this is as stable as one drive would be anyway, correct? I mean if I bought a 320G hard drive and used that, or 2 160G (which is what I have), and used raid 0, I have the same chance more or less of the single drive, or the array failing, right?

If that is correct, and I really don't have to worry about much else, then I'll go ahead with that. Can I also hook up another driver as master on the sec ide, w/my burner slave, and backup manually to that drive? As in, it's recognized as a regular drive, which would not be effected by a failure in the array? IF so that sounds the best for me: 2 drives rai 0 for speed, but back up the little secure stuff I need to this sec ide master drive.

One other question, do all regular apps work the same under raid 0? Will norton, and defreg apps all still work the same? To xp, is this array appear and work exactly like a 320G driver would for all intents and purposes under xp?

Thanks for all your help btw, this has been a surprisenly hard topic to find info on from people that actually use raid

 

[lesgray]

Hi Atomicboy22:

In general terms, the raid 0 (2x160GB)has a slightly higher chance of failing than a single 320GB drive. Just a numbers game, better chance of a problem developing on one of two drives, rather than on a just single drive.

However, the speed increase will more than justify the use of the raid 0 in your situation. You should be pleased with the results.

The idea of using a third drive on the secondary ide chain is very good, actually excellent. As long as you backup your critical data fiels, you be very happy with your setup, I think. If you can, I'd make an image of your initial setup, including all your installed programs and Windows updates, preferably to CDR or CDR-W. Most imaging programs will span CDs, so size of the initial install should matter too much. Then regular back-ups of your files (including email) on your third hard drive should keep you out of trouble. If a hard drive on the stripe should happen to fail, then the time required to rebuild your system should be kept to a minimum. If you make major changes to your installed program base or a significant amount of time has passed since your intial setup and things are still running smoothly, remember to create another image on CDs to reflect the major changes. This will further reduce rebuild time in case of disaster.

I may sound the disaster bell too often, some people might say, but I have been there. I've rebuilt a few of my own raids of varying types and rebuilt quite a few of my customers' raids. It only takes a little time every now and then to create an image of your entire drive. The hope is you'll never use it. But if you ever need to.....


To answer the last question, the array will appear to the utilities as a single 320GB drive. ALl of them should work normally under XP, 2000 or 9x.


Les Gray

http://www.creartec.com

 

[Atomicboy22]

LOL I just rear my thread, sorry I don't know why mentally I type "driver" when I want to type "drive", I do it all the time.

Also, just to get this right, when setting this up, I set up the array, then does the format occur there, or where it usually does in the xp installation? I know I have to hit F6 to install third party driver, are there any other things I should know? I have the updated driver btw, read about those problems...

 

[lesgray]

The format will occur where it ususally does in the XP setup. Setup the array first in the raid card bios setup, then boot up the XP CD normally. You will have to do the F6 thing, as you already surmised. The updated drivers are a very good idea - should have remembered to say that myself. XP setup should then find a 320GB drive for you to install on.

Something is suddenly bothering me about the size of the array. I think XP will see an array that size, hopefully it isn't only if sevice pack one is already on the install disk. Let me know...

Good luck;

Les Gray

http://www.creartec.com

 

[Atomicboy22]

Oh crap, I forgot about that too, it will only recognize 137G or something won't it... I don't have a sp1 install disk. IS this going to create a problem? Do I simply have to do the updates and it will be recognized then? The largest drive I've ever worked with is my current 120G, so I've never run into this.

 

[SYAR2003]

Hi !
Exellent summary Les .
I'm not sure this applies to atomicboy but .
People having e.g a 160gb ide drive , and goes for the new hot thing SATA disks in Raid 0 setup .
Theese have an excellent solution really if their structured.
Use compressed backup and use/keep the "old" ide drive as a "manual" backup storage for backupsets from the raid disk .

As mocking around with the raid array and setup without backup is dangerous also.

 

[Atomicboy22]

How about for the install though syar?

It will only format this array to 137G won't it? The version of xp pro I have does not have sp1 integrated... How will I get around this?

 

[SYAR2003]

Basicly atomicboy i was thinking about them that goes for
SATA drives , they can still have their "old" ide as a
normal basic ATA disk in the system .
This will apply for you to of course if you have a free ide channel for it .

 

[Atomicboy22]

ok, but how do I get around the installation from a version of xp pro that does not have sp1 integrated?

 

[SYAR2003]

If you have a burner i guess you ought to make a
xp boot cd with sp1 yourself.

Directions:

http://www.windows-help.net/WindowsXP/winxp-sp1-bootcd.html

 

[Atomicboy22]

LOL I just came across slipstreaming, and I was going to post here to ask either of you two if you knew if this would work. So this should work for my twin 160G in a riad 0 array, installing xp like this with sp1 installed? I hope this is the last obsticle I will have to adress, I really don't want to crack the packaging on these drives only to find out it won't work Let me know, and thanks for both your help

 

[IslandCustom]

Wow, this thread's really growing at a fantastic rate. Now I see that video editing is in the picture (no pun intended). Forgetting for the moment whether you decide on RAID 0 or RAID 1, video editing works better if you dedicate an additional physical drive to the video data, while the OS and video editing software run on your RAID drives. In that case, you'll certainly need two identical drives for RAID and a third drive (any size -- usually larger than the RAID drives) for your video data. Once edited, you can either back up your videos to your RAID drives or burn DVD's.