A couple simple questions about RAID 0

kkelln
kkelln used Ask the Experts™
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Hello;

I just bought an Asus A7N8X mobo with the Silicon Image Sil3112 onboard IDE ATA100 RAID controller. I will be using the system for video editing, among other things. I want to arrange two IDE drives on the controller for increased speed purposes. Accordingly, I will use the drives in a RAID 0 configuration. Now, a few questions:

1. Do I need to have EXACTLY the same two drives down to the model number? How much tolerance do I have in terms of mixing and matching drives? You see, I already have a 7200 RPM ATA133 from Maxtor, but they don't make this particular model any more (or so I have been told). I want to know whether I need to buy 2 new drives or just 1.

2. Does hard drive buffer size play much of a role in performance in the RAID 0 configuration I am proposing? I was looking at those new Western Digital drives with mb cache, but they are all 100ATA instead of 133.

3. Finally, which is better: ATA133 drives with 2mb ram or ATA100 with 8Mb ram?

Your help is GREATLY appreciated!
Kirk
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Commented:
1) You don't require two exact same drives. What you do need are:
   - two drives of the same capacity (if the drives are of different capacity, the capacity of the RAID-0 will be the double of the capacity of the smallest drive)
   - best is to have two drives that are about the same speed (if one is slower, the other will always have to wait for it)

   Of course, having identical drives is optimal, but isn't absolutely necessary.

2) See three.

3) This article/test explains/shows the difference between discs with 2MB cache and discs with 8MB cache: http://www.tomshardware.com/storage/02q1/020305/index.html

   Today, it is probably better to buy a Western Digital disc with 8mb cahce memory, simply because they're the only ones which still come with a 3 year warranty.
   But remember, the faster discs will always have to wait for the slowest.

As conclusion I'd say that if your financial situation allows it, I'd advise you to buy two new identical discs for the RAID-0 setup. This will give you the best performance.

Commented:
I know my previous comment to be true because I am currently running a RAID-0 consisting of 2 Maxtor 20GB ATA/100 drives and 2 Maxtor 20GB ATA/133 drives.

Author

Commented:
Suppose I have the following three drives:
Maxtor ATA 133 7200RPM 80gig w/2Mb cache
Western Digital ATA 100 7200RPM 100gig w/8Mb cache
Seagate Baracuda ATA 100 7200RPM 60gig w/? cache

I want to use the bulk of the Seagate for backup.

How do I configure the system? What about the following:

Connect the Western Digital as the primary on the RAID 0 and the Maxtor as the secondary (I only have room for 2 drives on this RAID controller). I create a 20 gig partition on the WD formatting with NTFS and install W2000 into this partition, which will be my boot device.

Next, I create a logical stripe drive (RAID 0) using the remaining 60gigs on the WD and the 60gigs on the Maxtor.

I connect the Seagate to the mobo's internal IDE controller and create 2 partitions. The first in only 1gig and the second is the remaining 59gigs. I install my W2000 cache/paging file onto the first partition.

*****CUYNEN: thanks for your spedy response!

Kirk
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Commented:
My pleasure.



I assume that by 'logical stripe drive' you are referring to a 'stripe volume' created in Windows 2000.

The solution you present works naturally, but it has less performance, because Windows 2000 and the CPU have to perform the RAID processing. Should you ever run into problems with Windows, and you have to reinstall, it is likely the data on the partition is lost.

I noticed you reserved a 1GB partition for the page file. In my opinion that's a bit small. I'd choose 2GB to 2.5GB.



With the discs you present, creating a RAID-0 via the controller will result in a loss of 20GB of storage space. In my opinion storage capacity is more important than read/write speed.

Author

Commented:
Hi again Cuynen;

Just to be clear then, given the drives I listed, how would you configure them? Do I create a single stripe volume that spans the WD and Maxtor, then walk away from the 20 unused gigs on the WD? Which drive would you make primary? Do I install W2000 into the stripre volume?
Also, you used the phrase "via the controller" - what does this mean? Thanks for the help. If you can get me through this I am more than happy to award you the points. I have very little knowledge and no experience setting up RAID controllers. My priority is performance FIRST, then security, then storage space (volume).

Thanks again

Commented:
With 'via the controller' I mean: creating the RAID-0 using the BIOS of the controller.

If any part of my explanation isn't 100% clear, please don't hesitate to say so.

What do you mean by 'security'?

Author

Commented:
By 'security' I mean reliability of the media (ie. data loss). So then, my most important goal is to set up the system to maximize performance. Second, I want to have the lowest possible chance of data loss WITHOUT compromising performance. Finally, having first maximized performance and then maximized reliability of the system under the performance umbrela, I want to maximize space, which is just to say that I want to have the most HD space I can without compromising the performance or security as described prior.

Thanks.
Kirk

Author

Commented:
By 'security' I mean reliability of the media (ie. data loss). So then, my most important goal is to set up the system to maximize performance. Second, I want to have the lowest possible chance of data loss WITHOUT compromising performance. Finally, having first maximized performance and then maximized reliability of the system under the performance umbrela, I want to maximize space, which is just to say that I want to have the most HD space I can without compromising the performance or security as described prior.

Thanks.
Kirk
Commented:
I was just reading an article at Tom's Hardware. It appears that, unlike the info found in the Windows 2000 doucmentation says, Windows 2000 will also require the full disc to be pu tin a stripe volume. The extra space you have left over when using discs of different size will be lost.



Here's what I suggest:

1) Put the Maxtor and Seagate on the RAID controller. Maxtor = primary master, Seagate = secondary master.

2) Put the WD on the mainboard's controller.

3) Set the mainboard BIOS to boot from the RAID controller. This is only necessary if the RAID controller is built into the mainboard.

4) Use the BIOS of the RAID controller to create a RAID-0. If you are asked for a cluster size, select 16K. The array will be about 120GB.

5) During installation of Windows 2000, create all partitions as mentioned in my following comment, but only format the first. It is important for performance that you don't format the others.

6) When Windows 2000 is installed, format all the other partitions with a cluster size of 16K.

7) Move the page file to drive D:\.

Commented:
Disk 0 (120GB) - this is the RAID-0:
   3GB - install Windows here - drive C:\
   ?GB - install programs here - drive E:\
      a seperate partition for your programs files, to eliminate the chance of your programs fragmenting the operating system's files. Make sure make this partition large enough
   ?GB - partition this as you wish

Disk 1 (100GB):
   2GB - page file - drive D:\
   ?GB - partition this as you wish

Commented:
Good protection against data loss and performance rarely go hand in hand. Only in more expensive systems (RAID-3 / RAID-5 setups) is this accomplished. By 'good protection' I mean that no data is lost, nor does your system stop functioning when a drive fails.

In your case, to minimize data loss, I suggest you use the second (the WD 100GB) as a backup of your data. If it's possible I'd also make an image (Ghost) of drives C:\ and D:\. This allows to, in case on of the discs in the RAID-0 fails, to very quickly restore your operating system and get going again.

Commented:
Glad I could help you out.

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