Are RAID arrays worth it?

[latrosicarius]

Hi guys, I recently had trouble with a RAID array I had. You guys all gave great advice, but the end result was I lost all my data

Since I was since able to reformat the drives and continue on, I figure the problem was not with the drives themselves but with the motherboard's onboard RAID controller. I could not enter it. None of the F-Keys worked like usual to enter the RAID controller, so I ended up having to purchase a PCI add-in RAID controller card.

Recently my friend stumbled into a similar problem with his hard drives where he now cannot RAID his drives because the motherboard's controller is not accessible. He, unfortunately has a SLI system running on a Micro-ATX form factor motherboard ahd has no room for a RAID controller PCI card.

I also learned through my ordeal that there seems to be no industry standardization in RAID controllers, meaning you CANNOT simply unplug two striped drives from one motherboard and plug them into another motherboard without losing all your data when you setup the array.

Furthermore, you apparantly cannot swap one RAIDed array for another RAIDed array without having to setup the array again, and lose all data on the new drives, and lose the ability to replace the old drives.

So my question is what, if any, are the benefits of using a RAID array if you value your data? I realize that RAID-1 (mirroring) is supposed to keep your data safe, but if you can't swap one mirrored array with another, than how are you supposed to keep separated backups, etc? Just because you mirror your data on two physical drives doesn't mean that the RAID controller itself can't screw up BOTH drives at once by messing up the master boot record.

[mike_w]

I think the point is that, in many cases, the main reason for mirroring is that hard drive failure is the weakest point in the system, so having two (or more) copies of the same data is much safer. When you have things like servers, you're unlikely to be regularly swapping arrays in and out. Even in workstations, you wouldn't swap HDDs out all that often.

Mirroring does not protect against viruses, user stupidity, broken RAID controllers, etc., nor should it really have to. That's what backups are for, whether it be onto CDs, DVDs, tapes or any other media.

[Slamdog]

i personally wouldn't ever have a use for a raid array in a home situation, preferring to utilise each disk in its own right. in a server scenario though raid works very well.

[atrull]

my server at home has a raid array, as I wanted somewhere to keep all my data.

Really, it depends on how much you are willing to pay, and what you want. Disks are so cheap now that a 1TB raid array, which would let you safely lose a disk with some performance loss (even the best disks eventualy fail ), can be easily built for significantly less than half a grand. a 1TB raid array is the equivalent of 200 DVDs, which is alot when you can't be bothered to look through your DVDs.

Since so much I do involves computers, I've got alot of data I want to protect. I'd recommend a raid mirror for any working situation that wants to avoid unnecessary data loss which could impact your operations, business or private. raid5 makes more sense for power users who want to maximise their space/quid ratio. I went for raid5. I can lose a disk and I won't lose all my precious data.

Recently I put a server online that has a small (80 gb) mirror - that'll serve me well for a while, since 80gb is still alot of space.

[RavenNight]

As long as you regularly back-up onto a more reliable media RAID is fab. I was stunned by the performance increase i got after RAIDing my Hard Drives. WIth the onboard problems, my mate had that but he just flashed the BIOS and all was well.

[shaithis]

Well, to be perfectly blunt; On-board RAID controllers are crap (as it sounds like you found out)....also, most add-in cards are no better then on-board.

IMO, you really need to spend a MINIMUM of around £150 to get a decent RAID controller. You also want RAID5 for simplicity (requires 3 or more drives and you lose the capacity of 1 drive). Some RAID controllers will let you add more disks and extended arrays but you are then getting into big money.

For me, RAID5 is a godsend. The chances of 2 disks dying at the same time in my system are pretty slim (probably just cursed myself there ) so as long as I dont go deleting important data I should never lose the information I have and in the 1.5 years I have been running RAID5, I haven't lost any data but I did have a disk die only a few weeks ago - RAID saved me a LOT of time then

[directhex]

it's also worth reiterating the difference between hardware, fake hardware, & software RAID:

anything costing less than about £200 for 8 ports is a "fake" RAID controller - in that no RAID operations are done by the controller itself, instead it relies on a Windows driver and your host CPU. You can't just switch controllers when using fake RAID, since each vendor's driver does things differently. This tends to be for Windows-only, bar Highpoint, who have closed-source fakeraid drivers for Linux and FreeBSD.

anything costing more than that is usually a real hardware RAID controller - this will have a dedicated CPU to calculate the RAID data, and often require no drivers for any OS to operate. This means brands like 3ware, Arcea, LSI, Intel. This also usually means 64-bit PCI-X, or 4xPCIe. Again, you usually can't swap controllers when using hardware RAID. An advantage of hardware RAID is it's entirely OS-independant - any OS can use the same array.

software RAID is where your OS treats the disks as normal disks - and does all the RAID stuff itself. the distinction here is that regardless of the controller, as long as you just see "a bunch of disks", the semantics of RAID are left up to you. given the speed of a modern CPU, software RAID (and fakeraid) can often give better performance than hardware - albeit with a CPU load penalty. The advantage of pure software RAID is you can change controllers whenever you like - or even use the normal IDE/SATA connectors on a motherboard - but this is NOT happy to go between OSes at all. i'm not sure whether Windows has any proper software RAID support, but all *NIXes do.

the final thing to remember is that RAID only protects you against simultaneous disk failure. RAID IS NOT AN ALTERNATIVE TO KEEPING BACKUPS - when the controller/filesystem get toasted, you'll wish you'd splashed out on a DVD writer or tape drive.

[Butcher]

Windows (NT/2K/XP) supports software raid (not sure which levels though).

[directhex]

Originally Posted by Butcher

Windows (NT/2K/XP) supports software raid (not sure which levels though).

can you do it at installation-time, or on a boot volume, though?

[Moby-Dick]

Software Raid is a complete and utter waste of time. If you aren't going to use a decent controller then it really is better of saving the money and spending on a better backup device.

as Direxcthex said.... RAID is not a substiute for backups.

[directhex]

Originally Posted by Moby-Dick

Software Raid is a complete and utter waste of time. If you aren't going to use a decent controller then it really is better of saving the money and spending on a better backup device.

as Direxcthex said.... RAID is not a substiute for backups.

software raid isn't a waste on linux land - it's actually quite common & populat to ship with a controller like a 3ware escalade 8500, then use linux software raid (mdadm) rather than use the card's hardware raid support, since the host cpu is so much faster (and has so many cycles to spare) that I/O throughput is better with software instead of hardware

it's "fake" raid which is a waste, for the driver concern reasons mentioned

[Moby-Dick]

interesting - I was thinking of the windows dynamic disk function , which is about as much use as the popes happy sacks !

[directhex]

Originally Posted by Moby-Dick

interesting - I was thinking of the windows dynamic disk function , which is about as much use as the popes happy sacks !

well mdadm volumes are *easy* to recover if something goes slightly odd. there's a difference

[Moby-Dick]

furry muff

I tend to stick to smart array ones as they are at least predicatable

[BlackDwarf]

I don't run RAID, all my 650Gb of space is randomly dotted about different disks... when one of them goes, i'm pretty much stuffed... So how do I (realistically) back up so much stuff minus getting 2x 400Gb external drives (which is more sence to put into the system itself and redundant the original drives after transfer?

[directhex]

Originally Posted by BlackDwarf

I don't run RAID, all my 650Gb of space is randomly dotted about different disks... when one of them goes, i'm pretty much stuffed... So how do I (realistically) back up so much stuff minus getting 2x 400Gb external drives (which is more sence to put into the system itself and redundant the original drives after transfer?

tape. get your wallet out & bend over.