How to read data from RAID0 set on a different computer?

July 1, 2009 2:05 PM

Will I be able to access data from a RAID0 array on a computer other than the creator of the set?

I plan to create a 1TB stripe from two 500GB drives in removable caddies on my Asus A8N-SLI Premium board, using the on-board Silicon Image 3114R RAID controller to back up a 1TB stripe on the other RAID controller on this board.

My concern is that should my computer be stolen, how would I be able to read the data off this RAID array without the original motherboard?

Would I need to connect the drives to the same motherboard model? Or just the same Silicon Image RAID chip? (perhaps on an expansion card)


If the disks in the RAID set cannot be read by any other hardware but the original, what would be the best way to back up 1TB of data across two removable drives?


Many thanks!

posted by ilumos to technology (8 comments total)

Our experience in the office with a bunch of RAID controllers says that you can usually access the drives on another computer with the same controller. Usually, but not always. And you definitely cannot count on being able to get the same controller at a later date. So I would not rely on this at all.

You need some kind of backup method anyway. It's even more important with a RAID0 array as a failure of either drive will cause the whole array to be lost, and that's more likely with two drives than with one.

A small collection of external 1 TB USB hard drives will probably be the best backup system for casual use. Use whatever backup software comes with your OS and store the backups elsewhere. Even just 2 drives used for alternate backups would be better than what 99% of people do.

Don't use just a single drive for backups though, Murphy's Law says your RAID array will die *while you are backing it up* and then your backup will guaranteed to be no good either, as you're in the middle of over-writing it. You want to arrange it so that at all times you have at least one good backup to rely on.
posted by FishBike at 2:26 PM on July 1

If the controller, BIOS, and drivers are the same on another motherboard, you can probably read the array on it.

Given the crapshoot that tends to be, this is why I tend to strongly recommend pure software RAID or RAID cards for doing this, since either makes it a lot easier to rebuild.

Also, to amplify FishBike's comment, please do remember a two disk RAID0 array is twice as likely to fail as a single hard drive, and take appropriate backups.
posted by rodgerd at 2:40 PM on July 1

If data integrity is your main concern, please don't do RAID 0 - the only reason to ever do raid 0 is for a speed increase, but that is a very limited use, where data integrity is positively not required. Especially if you'll be taking the drives out. You essentially double your failure chances in this scenario.

Now on to your actual question - different raid controllers lay out stripes differently. While it is possible to get the data off a raid set, it isn't easy (unless you are lucky). Importing the data with the exact same controller and version should be easy, depending on your controller. A similar chipset/version may or may not work.

Expect these kinds of problems.

If you just need 1tb of data and you don't do a raid but instead a JBOD raid, you will have a better chance at recovery. JBOD is pretty simple, but with no benefit outside of a bigger addressable space.

All of this being said, you'll save yourself a huge headache if you get bigger drives and do raid 1. Raid shouldn't be considered a backup, ever. Use another set of disks. And the last part of your question is totally dependent on the OS. If it's Windows, I REALLY like xxcopy for it's robustness. It clones drives quickly and easily.
posted by bensherman at 2:50 PM on July 1

Many thanks, lots of very useful comments. I wasn't clear in my original post, the RAID0 array on the Silicon Image RAID chip is infact a backup of another RAID0 array in the same system. Coupled with that I synchronize all my data to an external 1TB drive daily.

So ultimately I have two backups of the data, one backup on the two removable 500GB drives (on the Sil 3114R chip) and one on my external 1TB drive.

Taking all of your helpful comments into consideration, I may buy a PCI or PCI express RAID add-in card (or two...) to ensure that if my motherboard dies, or my computer is stolen, I can restore the data using another computer.

Does this sound like an adequate solution? If you had the hardware I have, how would you set it up?

I have 4 500GB drives (2 Seagate, 2 Hitachi Deskstar, yes I know...), one WD MyBook II drive (which I synchronize with the data in my computer, and use as external storage for my mac) and a 250GB drive for my OS (which I'd obviously want to perform as fast as possible).

I have two SATA controllers, the Silicon Image and the NVIDIA controller. I am lead to believe that the NVIDIA controller is far faster, as it is part of the nForce chipset, and does SATA 3.0Gbps, whereas the Silicon Image controller is on the PCI bus and only does 1.5Gbps.

Also, in testing, the two Hitachi drives performed far worse in the NVIDIA RAID0 stripe than the Seagates, though they are both SATA 3.0Gbps drives. Strange...


Lots of info there for you now!

Thanks so much guys, metafilter is truly an excellent community!
posted by ilumos at 4:11 PM on July 1

Taking all of your helpful comments into consideration, I may buy a PCI or PCI express RAID add-in card (or two...) to ensure that if my motherboard dies, or my computer is stolen, I can restore the data using another computer.

This is pretty reasonable - something like a decent Promise or Highpoint (for example) controller can't hurt - and a spare definitely won't.

Does this sound like an adequate solution? If you had the hardware I have, how would you set it up

It would depend on the operating system and what you're RAID0ing for. If I was running Linux and squeezed for IO but had plenty of spare CPU, I'd probably software RAID so I was completely hardware independent.
posted by rodgerd at 4:18 PM on July 1

I like the software raid idea if you can afford the CPU time.
posted by bensherman at 6:31 PM on July 1

Given that this particular RAID0 array is a backup, it presumably doesn't have a super-high performance requirement. If that's the case, you should set it up as JBOD rather than RAID0 as bensherman suggests. Better still would be to have them as separate drives, using standard partitioning (no fancy Windows dynamic partitions or Linux volume management), and use backup software that can split a backup archive into multiple independently-recoverable files. If your backup consists of say fifty archive fragments per drive, and each drive is independent and has plain vanilla partitioning, the number of data recovery tools available to you is much higher.
posted by flabdablet at 7:34 PM on July 1

Beware of onboard RAID controllers. I suffered untold consternation with a similar setup. I thought it would be faster. But it wasn't. The "normal" ports were connected directly to the bus of the computer via some kind of fast internal pathway. But the onboard RAID was just hooked into the PCI like any other card. Meaning it was doomed to only go @ 33mhz, and only when it wasn't competing for resources with other PCI devices. A software raid on the regular ports was tremendously faster.

You'll have to get into the specs of your motherboard to see if doing RAID0 is even worth it at all.

Since this would be a backup of a main raid, I wouldn't even bother with it. Format the drives as fat32 and set up a script that copies the data to the bare drives. The data will then be accessible on just about anything you plug them into.

Also, what you are (in essence) doing is creating a RAID10 device. A mirrored set of RAID0 devices. You might get better performance and capacity value setting up a RAID5.
posted by gjc at 5:48 AM on July 2