[eleasias]

Hi,
I was wondering if there is a way that, if you have 3 hard drives, you can set up 2 of the hard drives in RAID configuration, and the third drive not. Also, what is yoru opinion on whether RAID is a good idea or not. I have read that there is a high rate of failure of raid configurations, and I don't want to take the risk if it is not a good idea. Thanks for any help you can provide.

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RAID 0: Striped Set (2 disk minimum) without parity: provides improved performance and additional storage but no fault tolerance from disk errors or disk failure. Any disk failure destroys the array, which becomes more likely with more disks in the array.
RAID 1: Mirrored Set (2 disks minimum) without parity: provides fault tolerance from disk errors and single disk failure. Increased read performance occurs when using a multi-threaded operating system that supports split seeks, very small performance reduction when writing. Array continues to operate so long as at least one drive is functioning.

quote from: http://en.wikipedia.org/wiki/RAID

Basically RAID 0 will increase data access time but if you lose one drive you lose all the data.

RAID1 will actually mirror the data across two drives so you have the data if you lose a drive.

As for the high rate of failure look at it this way, more drives = greater likely hood of failure. A RAID 1 configuration would take care of that because its mirrored.

There are other levels but they need more disks. As for the third disk it can be added as another drive not being part of the RAID system.

[jaxisland]

RAID 0: Striped Set (2 disk minimum) without parity: provides improved performance and additional storage but no fault tolerance from disk errors or disk failure. Any disk failure destroys the array, which becomes more likely with more disks in the array.
RAID 1: Mirrored Set (2 disks minimum) without parity: provides fault tolerance from disk errors and single disk failure. Increased read performance occurs when using a multi-threaded operating system that supports split seeks, very small performance reduction when writing. Array continues to operate so long as at least one drive is functioning.

quote from: http://en.wikipedia.org/wiki/RAID

Basically RAID 0 will increase data access time but if you lose one drive you lose all the data.

RAID1 will actually mirror the data across two drives so you have the data if you lose a drive.

As for the high rate of failure look at it this way, more drives = greater likely hood of failure. A RAID 1 configuration would take care of that because its mirrored.

There are other levels but they need more disks. As for the third disk it can be added as another drive not being part of the RAID system.

[eleasias]

ok right. It worries me just because of the fact that in the raid descriptions, it says that (with raid 0) the whole array crashes if one drive fails. This just seems like a warning that raid array's often fail. IS there a high rate of failure, or is it usually safe to run a raid. Oh, and currently, i have a hard drive, not in raid, with alot of info. If i then set it up in raid 1 with another hard drive, would i lose all of the information on that drive. Thanks

[jaxisland]

With RAID your not doing anything that can increase in failure. All your doing is adding more drives. Your likely hood of failure is the same as a computer without RAID, the only failure is in the hard drive.

Now with RAID if a hard drive failure occurs, it will allow you to recover your data (excpet RAID 0).

So with RAID 1 you have two drives that are mirror images of each other, if one hard drive fails it will continue to write to the other drive until you replace it. When you put the new drive in, it will make it a mirror image.

As for your concerns on a high rate of failure, I will put it this way. If you have 3 hard drives and you set them up as one master and two slaves. You have the same chance of a hard drive failing as if you set up 2 in a RAID configuration and left one as a slave. Except in the first example if your boot drive fails, you will only have the data you backed up, in the RAID you will be able to continue on without losing any data you wrote to the RAID drives.

This system was set up to make sure that when hard drives fail, you wont lose your data (again excpet RAID 0)

With RAID 1 just make sure that the disks are the same size, becuase the array will only have as much space as the smallest drive, so its not worth the extra cost to have one small one and one big one.

[eleasias]

Ok so, in terms of my hard drive with lots of files on it, if i set it up in raid 1 with another hard drive right now, witht eh files already on it, would both of them be formatted first, or will the info from the hard drive be mirrored onto the other one? Thanks.

[jaxisland]

Assuming the array is set up correctly, with the drive that has your data being the first drive in the array, then it will not format them, it will just mirror over once it is configured.

[eleasias]

Just wondering about raid setups. I have 2 160GB hard drives, and a 320GB drive. I am trying to decide how to set these up in my PC. I don't know if i should install windows (Vista) on the 2 160GB in raid 0, or the 320GB. Whichever doesn't have the OS installed on it will be storage. Thanks for any help.

[jaxisland]

My opinion is to take the 2 160's make RAID1 and use the 320 as extra storage.

[eleasias]

Why raid 1? If i want better performance (speed) is raid 0 better?

[jaxisland]

If performance is what your looking for then yes. I misunderstood, I thought you wanted fault tolerence.

[eleasias]

Ok, could you give me a quick summary of raid 1 and raid 0? and if I'm going with raid 0, do you think it would be better to install the OS on the 2 160's in raid 0?

[jaxisland]

With RAID 0 you will have all 3 drives with their space. Set up the two 160s and install the OS there. BUT if one of the two 160s die, then you will have to replace it and format the other 160 because if 1 drive fails in RAID 0 then they both die. But you will get better performance because the drives split the data so you have two drives writing half the data, makes it twice as quick! (not a gurantee).
So with RAID 0 you have the combine space of 160+160+320

With RAID 1 you use the two 160s. What that will do is you install the OS on one and it will always make an indentical copy on the second drive. This does nothing for performance but if one of the RAID 1 drives fail, you always have a second identical copy. When you replace the broken drive then it will rebuild it so you always have a copy. In this scenario you only have the combined space of 160+320. (second 160 is just a copy of the first.)

If you go with RAID 0 then by default it is installed on both drives because its half on one and half on the other.

[eleasias]

Is there a large risk of raid 0 arrays failing? LIke, do they fail more often than a single hard drive would. so you think raid 0 would be the best bet for performance?

[jaxisland]

using the drives in a RAID 0 configuration doesnt increase the chance of failure. You have the same chance of one of the two drives failing if they were not set up as RAID.