RAID 1 question

[V00D00]

I recently setup a RAID 1 (mirroring) with 2 300gb drives. It works great and everything, but what happens when one of the drives dies or has a bad sector or something?

Worst case scenario, when one drive dies... how do I get my data back?

From what I'm reading I think the only way is to get another 300gb drive and rebuild the array, but that doesn't seem right. Is there any other way to do it?

 

[ND40oz]

Your computer should still boot and run with only the one drive connected. If you don't feel like buying another 300 gig drive or waiting for your RMAd one, you can always copy the data off the running single drive.

 

[Quasmo]

I was always confused about how it knows its dead or not. (If you dont have raid software installed)

 

[ND40oz]

The hardware raid controller stores the drive information, along with the drives. When it sees that a drive dies, it alerts you, on my hp/compaq scsi the drive blinks orange. When you hotswap in a new drive, the raid controller rebuilds the array in realtime. If you're doing a software raid, then you'll need the software. Kindof like having a hardware mpeg4 decoder vs using a software one and letting the processor due the work.

Perfect example. When I have to build multiple servers, I build one and either sysprep it or use sidgen after the fact. I can pull a drive from the running server, swap it into a new server, fire it up, run sidgen to change the name of the server and its sids and then pop in another drive and have it rebuild the array. Saves me time building servers.

 

[V00D00]

Well, I unplugged one of the drives while turned off, and after powering it up my RAID controller gave me a message saying there was an error with 1 drive and the other was loaded as a normal IDE, data intact. So that's good.

 

[Fullmetal Chocobo]

And you can then put another drive in, and it will begin the process of creating a RAID 1 array again (it will start mirroring the drive to regain redundancy).
Tas.

 

[homercles337]

Redundant Array of Inexpensive Discs. Raid1 -- Mirroring and Duplexing: Provides disk mirroring. Level 1 provides twice the read transaction rate of single disks and the same write transaction rate as single disks. Google is your friend.

 

[Fullmetal Chocobo]

Yay initializing RAID 5 array... 50.22% done, and 5.5 hours to go...
Tas.

 

[imported_Phil]

Originally posted by: homercles337
Redundant Array of Inexpensive Discs. Raid1 -- Mirroring and Duplexing: Provides disk mirroring. Level 1 provides twice the read transaction rate of single disks and the same write transaction rate as single disks. Google is your friend.

Only if the controller supports it, and most don't.

 

[Hacp]

Originally posted by: tasburrfoot78362
Yay initializing RAID 5 array... 50.22% done, and 5.5 hours to go...
Tas.

How does raid 5 work? When one drive dies, how do you get most of your info back???

 

[Fullmetal Chocobo]

Originally posted by: Hacp

Originally posted by: tasburrfoot78362
Yay initializing RAID 5 array... 50.22% done, and 5.5 hours to go...
Tas.

How does raid 5 work? When one drive dies, how do you get most of your info back???

RAID 5 is a modified RAID 3 basically. It is explained very well here. If one disk goes down, the RAID card can still calculate what is missing, and the array is still operational, albeit it is no longer is a redundant status. But if you throw in another drive, it sets up that drive into the array, and you are good again.

The bad thing about RAID 5, is two things I think (to me at any rate). They are relatively expensive to implement, as you have to have 3 disks, although it's much better if you have more. And it takes FOR EVER to initialize the array. You ahve to go through and setup all the drives to be the same (so to speak), and then it becomes redundant. It's annoying. But it's worth it.

This controller kicks arse. I can actually add drives to the RAID 5 array later. Or I can migrate it to a 50 or 50n array. It's awesome.
Tas.

 

[Hacp]

But some of your info is lost right?

 

[Fullmetal Chocobo]

Nope...
You know how parity works? If you rotate where the parity is placed (first one drive, then the next), you either have the information the need, and the parity bit is lost, or you have some information that is lost, but rebuilt by the use of the parity bit. See?
Tas.

 

[Conroy9]

I don't think RAID-5 is more expensive to implement, if you're only counting the drive costs - you will get more capacity out of your drives than with RAID-1

 

[V00D00]

I think that's what I'm actually going to do. Currently my 2 300gb drives only appear as one 300gb, while if I were to do RAID 5, I could get just one more disk, bringing me to 600gb, but still have the redundancy from the other drive.

Anyone know more info on RAID 0+1 and how it differs from RAID 5?

 

[imported_rod]

RAID 1+0 is exactly that. It is like a RAID0(stripping - which increases data transfer rates), and each drive is mirrored (RAID1). Problem is, it requires 4 identical HDD's, and you only really get the capacity of 2.

RoD