RAID Question

I am looking in the Technotes under Raid 5 and I have a question.

With Raid 5 you have to have a Minimum of 3 Hard Disks, but I am unsure on the minimum number of controllers a Raid 5 set up can have ? I belive the minimum number of controllers is one but I may be wrong? Also is there a max number of controllers a Raid 5 setup can have ?

Please advise.[/b]

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snadam

mgmguy1 wrote:

I am looking in the Technotes under Raid 5 and I have a question.

With Raid 5 you have to have a Minimum of 3 Hard Disks, but I am unsure on the minimum number of controllers a Raid 5 set up can have ? I belive the minimum number of controllers is one but I may be wrong? Also is there a max number of controllers a Raid 5 setup can have ?

Please advise.[/b]

Im not super positive as I havent dealt with RAID 5, but I think the minimum is 1 (hardware) controller that supports RAID 5

sprkymrk

RAID 5 assumes one controller. If you have more than one controller, you would have two RAID 5 arrays which you could mirror together to create a RAID 5+1 array.

ajs1976

With hardware RAID 5, it is the contoller that is actually doing the RAID. Normally all the disks are connected to the same controller. I guess it is possible that the disks could be connected to different controllers, but it is not something I have come across.

In software RAID 5, the operating system is doing the RAID. The disks could be on the same controller or different controllers.

So to answer you question, minimum would be one, maximum would be equal to the number of disks.

bighornsheep

For Hardware RAID solutions, I'm pretty sure that the minimum and maximum would be 1, otherwise, where will the array be stored?

If you wanted to improve the throughput of your array, you can put the disks on different channels, but they would have to be on the same controller.

For software RAID solutions, such as in Windows 2000/2003 or other software-RAID, you should be able to use disks from any channels, on any controller as long as it is detected and functional in the OS.

bighornsheep

sprkymrk wrote:

RAID 5 assumes one controller. If you have more than one controller, you would have two RAID 5 arrays which you could mirror together to create a RAID 5+1 array.

ajs1976 wrote:

In software RAID 5, the operating system is doing the RAID. The disks could be on the same controller or different controllers.

So to answer you question, minimum would be one, maximum would be equal to the number of disks.

Do I hear some echoes in the winds? Or have the 3 of us just been set up as a RAID-5 on TE.net?

ajs1976

I thought that was funny. When I clicked reply, there were 0 replies.

sprkymrk

ajs1976 wrote:

I thought that was funny. When I clicked reply, there were 0 replies.

Same here.

mgmguy1

Thanks guys for the responses. I just wanted to make sure that Raid 5 ment only one Hardware controller. Since Raid 1 Duplexing is where there are two controllers for both disks to the array, I figured that Raid 5 might come up on the test and I wanted to make sure as a stand alone question that raid 5 has one controller.

Anway, Thanks again

HemisFear

This is actually a legit question that is in the exam. Obviously it is not word for word but I had a question in regards to raid and how many controllers would be used in a particular situation.