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Raid 1 First Timer Questions

Last response: in Storage
January 11, 2007 8:42:01 PM

Here's my problem I'm upgrading my system to a Nforce 570 ultra chipset. I'm currently running a single 320gb drive and have a second drive which I would like to create a Raid 1 array with. From my understanding once you create an array it will erase all the data on the disks. Is that correct?

What I'm really looking to do is install the operating system on the empty drive so it's a fresh install, copy the data from the original drive to the new 320gb drive, and then get a Raid 1 up and going. Is this possible to do with Nvidias on board raid?

One final thing. So lets say a couple years or so down the road I'm running my Raid 1 array and am looking to upgrade my system. Can you simply take a drive out of the Raid 1 and plug it straight into a system without Raid functionality? How would you go about getting the Raid 1 to another system?

Thanks for your help everyone.

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January 13, 2007 3:09:46 AM

I think all this is doable, but it's tricky error-prone stuff (at every level, software, hardware, firmware, wetware and slippery finger ware, etc...) so it's best to have a reliable external backup of at least the critical stuff before even trying it, esp. for the first times.

RAID 1 is the simplest and easiest to maintain RAID level, and yes, for the most part drives can go back and forth from being RAID 1 drives and simple non-RAID'd drives, but it's still easy to mess up and lose all your stuff. For this, it's generally better to emphasize an external backup first before getting into RAID, esp. on a non-empty data set.

The way to do single drive to RAID array conversion in nVIDIA RAID configurations can sometimes be tricky. There are also several nVIDIA RAID revisions out there, so I can't say that what I've seen in the past will for sure apply to yours. But, there's a good chance that it will.

In order to install the OS on an nVIDIA RAID array, you must install the RAID drivers during the OS installation. This generally means creating driver diskettes with the RAID array, of course having access to a floppy for this purpose, and pressing F6 during the OS installation, and installing two drivers (SATA/IDE and RAID) during the OS installation.

Moreover, getting the nVIDIA RAID array to run with a single drive can mean running in a very non-intuitive configuration -- single drive RAID 0. This is in effect a regular drive, but with the RAID software installed. And once the drive is running with the RAID software, it's easier to convert that drive from one RAID format to another.

In converting a single RAID drive to a RAID 1 pair, you sometimes need to to tell the system to copy the data from the primary (original) to the secondary drive. The system is dumb, and if you make the mistake of specifying the wrong drive here, you can wipe your good data with an empty drive. The terminology isn't clear either, but as I recall, you issue the "rebuild" command to the drive you want rebuilt, not the drive from which you want the data.

I could be wrong about some of this due to revisions in the RAID hardware or software, but that's what I recall -- you must start off with a RAID array, and this might mean the non-intuitive single drive RAID 0 configuration, and from that you can create the normal RAID 1 configuration.

RAID 1 installation should really be more straightforward and intuitive, and sometimes it is, but I recall having to go through this non-intuitive part at one point, which is why I'm mentioning it. It could be that I was trying something a little trickier, such as converting in-place to RAID after having installed it without the RAID drivers provided via floppy during OS installation.

Again, for all of this stuff, you have significant data risk, so starting off with a full backup that you put aside and don't write to any further would be a good idea, unless you can afford to lose everything. A backup is a good idea in any case -- even with a functioning RAID 1 setup, an external backup will help protect you failure modes that the RAID 1 setup can't -- e.g. malware wiping the data. A backup can also help protect you from any mistakes or significant omissions I have made in this post.

The data backup is also a good answer to data migration and expansion questions. If you want to move / expand / etc., then make a full backup, create the new array, and then restore the desired data from the backup.
January 13, 2007 3:37:43 AM

Before you do anything, you may want to follow up this link and learn a little more about RAID arrays.

This is an excellent description of RAID.

You can't just pull a disk out of a raid setup and put it into another box. First, you will destroy the existing array, and lose your data. Second, if the new box doesn't include a a RAID set up, you will need to reformat the disk. Data loss again. Sounds like lose=lose to me.

As for RAID controllers on the MoBo, other posts here have indicated that there amy be concerns about the compatability of these controllers betweeen batches of a MoBo from the same manufacturer, let alone between revs of the same MoBo. Since I don't have any direct experience with RAID, the best I can offer is some links and cautionary observations.

Good luck.
January 15, 2007 12:43:32 PM

Best to do a full backup to DVDs, an external HDD, or another machine and then start the RAID 1 from scratch. And about migrating disks to a new machine...if you use motherboard-based RAID, you can be assured that it likely won't work. If you want to migrate RAID arrays from one computer to another and they are not identical machines, you have 3 options:

1. Back up all data to a third drive or other source, reformat the two disks and set up RAID 1 on the new computer. Then reload the data from the backup.

2. Buy an external add-in RAID controller card for your current computer and connect your HDDs to that, then use the card's RAID functions. To move the array to a new machine, simply take the card and HDDs out of the old computer and insert them into the new computer.

3. Set up a purely software-based RAID setup, set up and run through the OS. Windows has some limited functionality for this in Windows Dynamic Disks and the UNIX-like OSes have much more powerful software RAID functions. If you've done this, then just unplug the disks from the old computer and plug them into the new computer and tell the OS to look for the array and it should show up.

What you can't do is simply take one HDD out of a RAID 1 mirror and stick it into a new computer. It does contain all of the information, but it's also expecting to be in an array.