Simple raid question about mirroring drives

Jai9100 · 05-01-2009, 06:20 PM

Question for the braintrust. I have a 2tb external hard drive that's filling up fast and my plan is to buy another identical ext. hd and stripe them together using Apple disk utility for roughly 4 tb total. I know I'll lose the information on my current hd, but for the process I'll have access to a backup drive. In the future, I'd like to get 2 more drives, stripe them together, again using Apple Disk Utility, and then mirror the "two" drives to create redundantcy in case of a failure.

Is their any flaw in this plan? I, obviously, have a lot of data that I'm not willing to lose, and I don't think my projects will get bigger than 4tb.

And the big question: if I have data on the first set of striped disks already, will I lose that when I use Disk Utility to mirror the "two" disks?

Thanks in advance!

fmw · 05-01-2009, 06:54 PM

Be sure you need the information on a single volume. Combining the capacity of two drives into a single volume is way, way less reliable than a single drive. In your shoes I would probably get the raid unit and put drives in to start in a raid 1 configuration - mirrored drives. Then you could add drives as needed to increase capacity.

The only time you should combine drives into a single volume is when a single project or database won't fit onto a single drive. It is a fairly popular thing to do but a risky one if your data matters to you.

I'm not an Apple guy so I don't know how they work with raids within the system itself. I was assuming an external NAS or USB RAID unit in something like a 4 drive cabinet. If you have an inboard controller and room for the drives, then you wouldn't need that.

Jai9100 · 05-01-2009, 08:28 PM

Thanks for the reply, I've been muling for the last few days if I want to do the above stated, or just go out and get a raid 5 system (my preferred raid for what I want) with an external controller and more smaller disks. I think I'll go and get the real deal instead of having to mess with a software controlled system.

Thanks again!

fmw · 05-01-2009, 10:24 PM

If you're going to go with an external unit then go get something like a 4 bay RAID box. Then you can add the number and size of drives you like. Some are connectable via ethernet, some via USB and some go both ways. Synology makes some good quality RAID boxes. I've used units of theirs to backup some pretty serious networks. They have 4bay units ranging from $500 on up (without drives.) I prefer the external approach. That way it can serve as a backup while you use your internal drive or drives for normal processing.

**Cromewell** · 05-01-2009, 10:53 PM

It sounds like a nightmare to me. RAIDing external drives over USB connections just seems like a bad idea. Do you really have 4TB of files that have to be on the same drive?

fmw · 05-02-2009, 02:28 AM

Quote:

Originally Posted by Cromewell

It sounds like a nightmare to me. RAIDing external drives over USB connections just seems like a bad idea. Do you really have 4TB of files that have to be on the same drive?

I don't think you understand what a RAID box is. The entire unit is external. It houses the raid controller and the drives. USB is simply one of the ways to connect it to systems. The NAS units connect by ethernet. Same thing.

**Cromewell** · 05-04-2009, 06:12 PM

Quote:

Originally Posted by fmw

I don't think you understand what a RAID box is. The entire unit is external. It houses the raid controller and the drives. USB is simply one of the ways to connect it to systems. The NAS units connect by ethernet. Same thing.

I know what a NAS is and it would work fine. But that's not what the OP is asking about.

Using a bunch of external USB drives in a software RAID just doesn't sound like a good idea.

05-01-2009, 06:20 PM	#1 (permalink)
Jai9100 New Member Join Date: May 2009 Location: MN, USA Posts: 2	Simple raid question about mirroring drives Question for the braintrust. I have a 2tb external hard drive that's filling up fast and my plan is to buy another identical ext. hd and stripe them together using Apple disk utility for roughly 4 tb total. I know I'll lose the information on my current hd, but for the process I'll have access to a backup drive. In the future, I'd like to get 2 more drives, stripe them together, again using Apple Disk Utility, and then mirror the "two" drives to create redundantcy in case of a failure. Is their any flaw in this plan? I, obviously, have a lot of data that I'm not willing to lose, and I don't think my projects will get bigger than 4tb. And the big question: if I have data on the first set of striped disks already, will I lose that when I use Disk Utility to mirror the "two" disks? Thanks in advance!

05-01-2009, 10:53 PM	#5 (permalink)
Cromewell Moderator Join Date: Dec 2004 Location: Canada Age: 26 Posts: 11,802	It sounds like a nightmare to me. RAIDing external drives over USB connections just seems like a bad idea. Do you really have 4TB of files that have to be on the same drive? __________________ You know what the chain of command is? It's the chain I go get and beat you with 'til ya understand who's in command here. www.userfriendly.org

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
RAID 10 (0 + 1) or just RAID 0 ?	erebusting	Computer Memory and Hard Drives	23	03-15-2009 03:49 AM
Hopefully a simple question about RAM	bugs	Computer Memory and Hard Drives	3	01-04-2009 08:40 AM
raid hard drives	roadkillbob	Computer Memory and Hard Drives	2	03-22-2007 09:57 AM
A simple question...	b0zo	Computer Security	9	11-26-2006 06:06 PM
Got a question about RAID	gamerman4	Computer Memory and Hard Drives	5	10-13-2005 10:46 PM

05-01-2009, 06:54 PM	#2 (permalink)
fmw Gold Member Join Date: Aug 2008 Posts: 474	Be sure you need the information on a single volume. Combining the capacity of two drives into a single volume is way, way less reliable than a single drive. In your shoes I would probably get the raid unit and put drives in to start in a raid 1 configuration - mirrored drives. Then you could add drives as needed to increase capacity. The only time you should combine drives into a single volume is when a single project or database won't fit onto a single drive. It is a fairly popular thing to do but a risky one if your data matters to you. I'm not an Apple guy so I don't know how they work with raids within the system itself. I was assuming an external NAS or USB RAID unit in something like a 4 drive cabinet. If you have an inboard controller and room for the drives, then you wouldn't need that.

05-01-2009, 08:28 PM	#3 (permalink)
Jai9100 New Member Join Date: May 2009 Location: MN, USA Posts: 2	Thanks for the reply, I've been muling for the last few days if I want to do the above stated, or just go out and get a raid 5 system (my preferred raid for what I want) with an external controller and more smaller disks. I think I'll go and get the real deal instead of having to mess with a software controlled system. Thanks again!

05-01-2009, 10:24 PM	#4 (permalink)
fmw Gold Member Join Date: Aug 2008 Posts: 474	If you're going to go with an external unit then go get something like a 4 bay RAID box. Then you can add the number and size of drives you like. Some are connectable via ethernet, some via USB and some go both ways. Synology makes some good quality RAID boxes. I've used units of theirs to backup some pretty serious networks. They have 4bay units ranging from $500 on up (without drives.) I prefer the external approach. That way it can serve as a backup while you use your internal drive or drives for normal processing.