RAID Trust Issues — Windows Or a Cheap Controller?

NicApicella writes "My new system has two sparklin' SATA drives which I would like to mirror. After having been burned by a not-so-cheap, dedicated RAID controller, I have been pointed to software RAID solutions. I now stand in front of two choices for setting up my RAID: a Windows 7 RC software RAID or a hardware RAID done by the cheap integrated RAID controller of my motherboard. Based on past experiences, I have decided that only my data is worth saving — that's why the RAID should mirror two disks (FAT32) that are not the boot disk (i.e. do not contain an OS or any fancy stuff). Of course, such a setup should secure my data; should a drive crash, I want the system up and running in no time. Even more importantly, I want any drive and its data to be as safe and portable as possible (that's the reason for choosing FAT32), even if the OS or the controller screw up big time. So, which should I choose? Who should I trust more, Microsoft's Windows 7 or possibly the cheapest RAID controller on the market? Are there other cheap solutions?"

Comments

It's *NOT* hardware raid on your motherboard.

[Zarhan]

These motherboard "raids" are called fakeraids.

All that it is is that it writes the metadata on the disk in specific format so that you can see the raid volumes via BIOS. Note: Only "see" their status - in case you replace one drive, the resync is still done by software and you must boot to operating system. One clue is the fact that in Linux the dmraid package uses exactly same driver for accessing fakeraid-mirrored drives and Linux's own software-raids - device mapper just does a bit of magic at init.

However, if faced with choice of Windows-only or motherboard-raid, I'd go with the motherboard-version, because that's at least supported both by Windows and Linux so in case something goes wrong with your Windows installation you can always pop in Knoppix or some other Linux CD for recovery.

Re:It's *NOT* hardware raid on your motherboard.

[Grishnakh]

DO NOT buy a real RAID card unless you have a pretty good budget for your system, and need the highest performance. The problem with buying a real RAID card is that you need to buy not 1, but 2 or better yet 3 of them, so that you can have spares. If your RAID card dies (and they do, more often than you'd think), the only way you'll be able to access that data, because of the proprietary on-disk storage method used by RAID card vendors, is to have an identical card (with the same firmware version, to be safe). And since hardware is constantly being obsoleted, you need to buy your replacements when you buy your card, not hope they're still available later. It's also a good idea to have spares of the same make and model hard drive, because hardware RAID controllers aren't usually that flexible in allowing you to pair up different sized drives like Linux sofware RAID.

For many purposes, software RAID using Linux is really a much better solution, because the on-disk format is open-source and standardized, so it doesn't matter what hardware you have, you can plug the disks into a different Linux system and you'll be able to read the data with no trouble. The only downside is a slight performance decrease since the CPU has to do all the work, but even then unless the system is heavily loaded, it's still faster than hardware RAID because the hardware RAID cards aren't that fast.

With the giant drives that are now common, I think the best solution, at least for home/desktop systems, is to forget about RAID5/6 altogether and just get a couple of 1-2TB SATA drives and mirror them with software RAID 1 in Linux.

Re:Just remember the first rule of RAID 0

[Anonymous Coward]

That's nice, but the submitter is asking about RAID 1.

Re:FAT???

[jeffasselin]

No. NTFS is not perfect, but to think FAT is as bad is deluded. I've honestly never seen a HD formatted with NTFS that I couldn't repair with built-in tools, unless it had physical defects, and in such a case ANY file system would have problems. But I've seen so many FAT drives get hosed by little problems, it's not even funny.

Seriously, don't trust your data to a FAT partition - not worth it.

Re:Just remember the first rule of RAID 0

[Trebawa]

He wants to mirror the drives. This means he wants RAID 1. Therefore, the failure rate of the array is 1/2 the failure rate of each disk (more, actually, because they're like;y identical drives that will fail at the same time, but you get my point).

Re:Just remember the first rule of RAID 0

[mooboy]

Whoa, hold the boat. I've had a lot of experience with Dell & HP/Compaq(Proliant) provided RAID systems and they are not sensitive to disks with vastly different innards. All that matters is block count and software mirroring doesn't even care about that, because you'll simply be limited to the size of the smaller disk. If you're using mirroring or RAID, try to go with different makes of the same size. This article talks about MTBF. It turns out if 2 drives of the same exact model comes off the line and end up in your PC, there is a chance they could fail within a very close time to one another. So your mirror or RAID could fail permanently while rebuilding from the first failure. But if all your drives are of a different make, chances are they won't fail at the same time and you'll get the critical time needed to rebuild your array.

When I'm going to do mirroring or RAID on hardware that doesn't have high-end dedicated server RAID controller, I use Windows or Linux software RAID. Performance is surprisingly good and I'm not married to a specific hardware implementation. I've had _none_ of the issues you've described with Linux software RAID on several servers for several years. Mdadm has only whined after a power outage or genuine disk failure.