Hello,

We are currently working on building a new file-server. The biggest problem is that I am a programmer and only know enough about hardware to get myself in trouble. We are not so much in need of performance but of fault tolerance. So I am planning on using raid 1 mirrors.

Two biggest questions are:
1.) Should I use onboard raid controller or have it separate from the motherboard. My concern is if the motherboard fails, we will not be able to recover the data on the raid drives. Along with this, should I purchase two of the raid controllers in the event that the first fails. More broadly speaking, are raid controllers universal or manufacture/model specific.

2.) I plan to do two raid configurations: One raid set for the operating system and one for the data being served. Any recommendations or issues that can be given would be appreciated.

RAID 1 drives can normally be moved to any machine and will work as "normal" drives when connected to its native controller. Please read this http://www.tomshardware.co.uk/foru [...] et-servers then post any questions.

UD

Thank you for this link ... that helped me allot. However, your reply confused me just a bit. Does "native controller" mean the same controller (brand/model) as the raid was originally created with? If so does this mean that if the original controller failed then we would need another controller with of the same brand to recover the data?

Hi platics,

Sorry for the delayed reply.

Trying to keep it simple!

What I mean is that when you connect a hard drive to the motherboard there are is a chip that handles communication between the two. This is what I call native connection. When you have a RAID array you will still need the connection between the hard drive and the motherboard but you will need a chip "in-front" of the connection to perform your RAID functions. The RAID function that is performed on the chip depends on the RAID array that you have configured.

I'll compare RAID 0 and 1.

In RAID 0 the chip needs to take any information that you want to write to the disk and split it in half, then send half of the data to each disk in your array. When you read data the chip does the reverse, it will add the two "pieces" of information back together. If you took one of those drives and connected it to a native connection no usable information could be retrieved as the drive only holds half the data.

With a RAID 1 array the chip makes sure that the same information is written to each hard drive so there is no need to split or reconstruct any information. Since there is no need to reconstruct the information on the disk we are not dependent on a RAID chip to read the information on the drive, I can take the drive and connect it to a native controller and read everything off the drive.

There are differences in RAID implementations by different manufacturers so there is no guarantee that a RAID array that has been built on one brand will work on another. You would need to do your homework.

I hope this answers.

UD.

Thank you, that cleared it very specifically and was exactly the answer that I was looking for.

Typically the add in RAID controllers work better but tend to cost more. They will handle all the data processing and have cache built in on the card and will take strain off of the CPU.

Depending on how many users you will have accessing the information simultaneously would be the major factor in determining if you should use the onboard RAID vs an add in card. Intel uses its ICH9R controller on tons of boards so I would imagine they are interchangeable.

Typically you would use a RADI 1 for the OS and a RAID 5 for the data, but it really depends on what software you are going to be running.

The Raid Migration Adventure

http://www.tomshardware.com/2007/0 [...] index.html