howtogeek at May 7th, 2013 06:42 — #1
Originally published at: http://www.howtogeek.com/162676/how-to-use-multiple-disks-intelligently-an-introduction-to-raid/
RAID allows you to combine multiple physical hard drives into a single logical hard drive. This allows you to mirror your data across two hard drives, ensuring you always have your important data stored in multiple places.
kajutisg at May 7th, 2013 11:02 — #2
Good article. Only thing I would add is that disk manufacturers have specific hard disks that are "certified" for RAID use, & they're generally the higher end units that are much more money, hence use by business mostly & consumers rarely. I've heard of issues using "green" drives being unsuccessful & there's numerous postings about the TLER setting being an issue. I'm running WD "green" drives on a DELL RAID controller in a Poweredge 840 server, but I'm NOT using the RAID, just the controller.
acf at May 7th, 2013 11:28 — #3
Reminder... RAID =/= backup!
josephlogston at May 7th, 2013 11:47 — #4
will this how to, work with exterior USB hard drives
localhost at May 7th, 2013 13:29 — #5
You're right about the WD Greens being an issue. I had them in a RAID1 array on my home server and they were quite annoying because they kept dropping out of the array. Data loss wasn't an issue because I only had 2 drives, but the array wasn't performing well because it was rebuilding the data 90% of the time. Its that the drives enter a deep sleep state and that causes the controller to think they died.
If you're just using it on the controller it wouldn't be an issue at all since its a RAID issue.
There was a fix from WD that let you modify the time out, but I didn't feel comfortable trusting my data to drives that weren't meant to do what it was doing anyway. So I threw in the towel and bought 3x 3TB WD Reds and set up a RAID5 array. Haven't had a single problem since. The reds are meant to be used for 24/7 use anyway so thats some extra peace of mind.
dfhudson53 at May 7th, 2013 13:33 — #6
Conceptually, it should work. Practically, probably not a good fit.
I'd be surprised if a RAID controller would work with USB drives. Software RAID seems more likely to work. But for RAID to make sense, you really need two, or three, or more drives online all the time. With external USB drives, you (or someone else) can come along and unplug one at any time. That would probably foul up your RAID arrangement; at a minimum, you'd probably lose your data redundancy. The portable, flexible nature of external hard disks just seems to me to run counter to the whole notion of a RAID array.
themike at May 7th, 2013 17:50 — #7
my motherboard doesn't support raid.
pax at May 8th, 2013 06:52 — #9
Nice article, as often. I was wondering how much complexity you could bring into that. I mean, could you have 2 SSDs on raid 0 for 1st OS, another single SSD for 2nd OS and two HDDs in raid 1 that would backup 1st & 2nd OS.
The idea behind this is : 1st OS = super fast (like Windows for gaming), 2nd OS = fast (like Linux for daily use), both backed up and backup being double-secured (for the sake of backups). Is it a clever setup or complete foolish ?
Actually a NAS performing the backup work may sound better, may it not ? Cause having a nice NAS setup rock.
Though choices my friends.
jamesdwalsh at May 8th, 2013 12:46 — #10
Excellent point. Multiple chronologica backups allow you to recover to a selected previous state; redundancy only helps ensure the current state is not lost. If a system is infected or one wants a previous version of a file, backups (preferably disk images of the entire OS, programs, and data disks) are key.
untenops at May 10th, 2013 15:12 — #11
While its not a true RAID, I like to use greyhole on my server. It allows for more flexibility, in my opinion. For example you can JBOD, for your pool, and have a single copy of less important files and 2 or more copies of important files. Its all done by software, but it makes it very easy to remove, add or change out drives in the pool.