Having a 2TB in raid 1 with a 250gb drive

[AeroScap]

Recently my hard-drive just came up, (via ubuntu) with around 252 million bad sectors. Its clearly and truly on its way out.

I am thinking about purchasing a 2tb drive to replace the broken one.

At the moment, my pc is a dell prebuilt with 2 x 250gb WD drives in raid 0.

The 2 tb drive should be enough space and I dont want to waste the one remain drive. It would be better to have the two drives working as raid 1 so that the 250gb driveit backs up whats on the 2tb drive.

But is that even possible?

or is the best way is to keep them as raid 0 and have a 2.25tb drive?

[barry2811]

RAID1 would only use as much space as possible on the smaller driver, ie, you would have a 250GB RAID1 volume, and 1.75TB of either wasted space or a non-RAID volume depending on your chipset.

Generally, when using RAID, the same size discs are preferred.

[FatalSaviour]

That's an awful lot of bad sectors - are you sure Ubuntu's getting it right? Just to confirm, these are the drives that are in RAID 0. I've had issues with RAID arrays in Linux in the past, it might just be that throwing a wobbly.

I'm not sure what you're getting at in your next bit though...
Your (sensible) options are:

2x250GB in RAID 0
2x2TB in RAID 1

2x250GB in RAID 1
2x2TB in RAID 1

You could also do 2x2TB in RAID0 instead, but that's taking a big gamble with 4TB of data...

[FatalSaviour]

Ahhhh, I understand now! :-)

Yes, a 2TB drive in RAID with the 250GB wouldn't be great at all.

Also bear in mind that RAID does not equal backup.

It would be far better to use the drives independently, and a scheduled backup program to back up any important data from one to the other.

[AeroScap]

Ahhhh, I understand now! :-)

Yes, a 2TB drive in RAID with the 250GB wouldn't be great at all.

Also bear in mind that RAID does not equal backup.

It would be far better to use the drives independently, and a scheduled backup program to back up any important data from one to the other.

Thank you for your response fatal:

I think the topic is more appropriate here, so the replies can be together.

http://forums.hexus.net/hexus-hardwa...0gb-drive.html

Why is 2tb in raid with 250gb a bad idea? The 250gb, the other one is in working order.

I can see how your suggestion is a good idea, but how would you go about that?

[aidanjt]

No that'll work fine. Just create a partition of the same size as the 250gb one of type 'fd' (Linux RAID), and create the mirror array. MD can tollerate a ~1% partition size differential. Then you can make another partition for backups and unimportant files you don't mind losing and such.

[AeroScap]

No that'll work fine. Just created a partition of the same size as the 250gb one, and add it to the mirror array. MD can tollerate a ~1% partition size differential. Then you can make another partition for backups and unimportant files you don't mind losing and such.

So that partition of 250g that you first mentioned, that gets created on the 2tb drive correct? the where do you go to mirror array it?

[watercooled]

Let me just re-iterate what FatalSaviour said, RAID is not backup! It's designed for redundancy and so can be useful for servers which need to have as little downtime as possible. RAID covers a single problem i.e. single physical HDD failure, not the countless other problems which can destroy data, for example, accidental deletion, malware, PSU failure, power cuts, and so on. I also strongly recommend you add the 250GB drive to your offline backup plan - you do backup right? Keeping it in the PC as a backup drive is also bad practice, a good deal of the problems listed above would still affect it so it's not really an adequate backup.

In answer to your question though, yes it's possible, but I really don't see the point in a PC. I'd rather either have the extra space or just take it out of the PC. Also if you get a 'green' drive with a lower spindle speed, your existing 250GB drive might be faster for an OS drive.

Edit: Oh and using RAID0 will not give you a 2.25TB drive. You will have to create a 250GB partition on the 2TB drive then RAID0 them together to create a 500GB volume, then another 1.75TB of un-raided space on the 2TB drive. JBOD may suit your needs better if you just want to create a big volume across both drives.

[AeroScap]

Let me just re-iterate what FatalSaviour said, RAID is not backup! It's designed for redundancy and so can be useful for servers which need to have as little downtime as possible. RAID covers a single problem i.e. single physical HDD failure, not the countless other problems which can destroy data, for example, accidental deletion, malware, PSU failure, power cuts, and so on. I also strongly recommend you add the 250GB drive to your offline backup plan - you do backup right? Keeping it in the PC as a backup drive is also bad practice, a good deal of the problems listed above would still affect it so it's not really an adequate backup.

In answer to your question though, yes it's possible, but I really don't see the point in a PC. I'd rather either have the extra space or just take it out of the PC. Also if you get a 'green' drive with a lower spindle speed, your existing 250GB drive might be faster for an OS drive.

Edit: Oh and using RAID0 will not give you a 2.25TB drive. You will have to create a 250GB partition on the 2TB drive then RAID0 them together to create a 500GB volume, then another 1.75TB of un-raided space on the 2TB drive. JBOD may suit your needs better if you just want to create a big volume across both drives.

Firstly thank you for your post.

So when you say you want it for the extra space, you mean in a JBOD setup? and how would you go about doing that?

At the moment, if i understand i correctly, the options are:

1) 1.75tb of unraided on 2tb + 500gb (250gb drive + 250gb partition) as raid 0
(but bad sectors from one of the drives in raid 0 is what caused the problem to begin with, just going the same but with a new 2tb drive.

2) 2tb space alone. With 250gb offline backup.
(I have an external doing that already, which is why i would prefer the 250gb to remain in the pc)

3) 1.75tb of unraided + 500gb in raid 1 (250gb partition + 250gb drive) for redundancy)
(not ideal since the 250gb is the same make model spec brand as the one that failed)

4) Have both drives in a Jbod setup for one whole volume
(tracked down my motherboard to be "Intel P965" and from what I can gather supports JBOD)

is that correct?

[watercooled]

Drivers won't kill a disk - check SMART data, the drive might be fine, just the filesystem may be corrupted which could be solved with a simple wipe+format.

Setting up JBOD is much the same as setting up a RAID array, it just allows you to make one big volume across all disks in the array.

[FatalSaviour]

Firstly thank you for your post.

So when you say you want it for the extra space, you mean in a JBOD setup? and how would you go about doing that?

At the moment, if i understand i correctly, the options are:

1) 1.75tb of unraided on 2tb + 500gb (250gb drive + 250gb partition) as raid 0
(but bad sectors from one of the drives in raid 0 is what caused the problem to begin with, just going the same but with a new 2tb drive.

2) 2tb space alone. With 250gb offline backup.
(I have an external doing that already, which is why i would prefer the 250gb to remain in the pc)

3) 1.75tb of unraided + 500gb in raid 1 (250gb partition + 250gb drive) for redundancy)
(not ideal since the 250gb is the same make model spec brand as the one that failed)

4) Have both drives in a Jbod setup for one whole volume
(tracked down my motherboard to be "Intel P965" and from what I can gather supports JBOD)

is that correct?

If it were me, I'd install your OS on the 250GB on its own. Now depending on the make/model of your old and also your new 2TB drive, the smaller drive *might* be faster. Then, depending on how concerned you are about your data, keep your User folders (i.e. Documents, Pictures etc) on the 2TB and set up a regular backup.

Something else to note, the 250GB will almost certainly be a 7200rpm drive, whereas most 2TBs are 5400rpm. You have to factor in areal density which might make sustained read speeds faster on the 2TB, but I would imagine seek times would be quicker on the 7200rpm drive still.

Also, with option 3, you would have 1.75tb of unraided + 250gb (not 500GB) in raid 1 (250gb partition + 250gb drive) for redundancy)
This would be much more ideal than RAID 0'ing it, as RAID 1 would safeguard against the very thing you're concerned about - drive failure.

[aidanjt]

So that partition of 250g that you first mentioned, that gets created on the 2tb drive correct? the where do you go to mirror array it?

Yup, create a 250GB partition on the 2TB disk and use that partition for the mirror array. The Disk Utility provided by Ubuntu (also available on the LiveCD) can partition disks and create MD RAID arrays for you, you can also use the alternate Ubuntu install CD to install Ubuntu on the mirror.