Raid 1 versus two drives with SuperDuper?

[peterm1]

I currently have two 500GB drives set up in my Mac Pro in a Raid 1 array solely to store my photos. In the not too distant future, these drives will be full and I would like to replace them with two 1TB drives. I was planning to set them up in a RAID drive again, but since I have SuperDuper I was wondering if there is an advantage to using it instead of a Raid configuration to copy files from one drive to another. I don't need immediate second-by-second backup. If something catastrophic happens to one drive, is it easier to deal with the situation and access and copy the still working drive if the drives were copied using SuperDuper versus using Raid? (I realize I would lose any files since the last SuperDuper backup).

Thanks!

Peter

[dnanian]

Well, what it would do is protect you against making mistakes. A RAID is going to give you, as you said, second-by-second duplication -- so, disk corruption (non-hardware) is going to be replicated across both, as will file deletion/overwrite/etc.

The SD! backup would avoid these things. But it obviously wouldn't recover from a single-volume hardware failure as quickly, because in a typical RAID you could just swap drives and have it rebuild without any downtime.

[peterm1]

Thank you for the quick reply. So you are saying that if I am using RAID and replace a failed drive with a new drive, the RAID system would copy over the files from the drive that survived to the new drive a bit faster? That wouldn't be a big deal to me, since I don't keep a spare drive on hand anyway and would have to spend time going out and getting one, and the small increase in time it would take to copy over the files to a new drive using SD wouldn't mean much to me.

I am an amateur photographer so I don't have the need to have the absolute fastest recovery like a business owner would.

Thanks again - SD is a great product!

Peter

[dnanian]

A RAID 'fixes itself': basically, if one of two drives fails, the other takes over. At that point the RAID is 'degraded' and cannot absorb another failure until it's repaired with a new drive (at which point it 're-syncs').

I use RAID drives are the destination of my backups to give myself additional protection. I also use a RAID as my startup drive, and one that stores my critical data. In fact, nearly everything of importance is both stored natively and backed up on RAID devices for protection.

[galfromdownunder]

Originally Posted by dnanian

A RAID 'fixes itself': basically, if one of two drives fails, the other takes over. At that point the RAID is 'degraded' and cannot absorb another failure until it's repaired with a new drive (at which point it 're-syncs').

I use RAID drives are the destination of my backups to give myself additional protection. I also use a RAID as my startup drive, and one that stores my critical data. In fact, nearly everything of importance is both stored natively and backed up on RAID devices for protection.

David,
Could you give us a simple step by step dummies guide on RAID 1 (1TB-1TB mirror) for the sticky record, and how to use it with Super Duper. I have just bought one of those 2TB Lacie Triple Interface RAID boxes to store+mirror my off-laptop data, have a Powerbook G4 working nicely with Tiger for now (if it ain't broke don't fix it), and am scratching my head as to how to set it up, with a view to using SuperDuper if applicable. For example, Disk Utility shows "Partition" and "RAID" yet the instructions ignore that RAID tab. It also shows options under Partition that don't square with what I'm seeing - they show a JBOD ("just a bunch of disks"!) as an example which doesn't appear in my pull down menu under Partition.
The Lacie manual is pretty obtuse, and talks about the enclosed Retrospect software ... how does that relate if at all.
Thanks, I am sure as we all get more and more stuff filling our small capacity drives, we'll need this info.

[dnanian]

There's nothing tricky to do, and no need to use Disk Utility to RAID it. Instead, it has hardware RAID built in. You should set that to "mirrored", and treat it like a regular drive... the RAIDing is transparent to the user.

[galfromdownunder]

Originally Posted by dnanian

There's nothing tricky to do, and no need to use Disk Utility to RAID it. Instead, it has hardware RAID built in. You should set that to "mirrored", and treat it like a regular drive... the RAIDing is transparent to the user.

But it came in the box with the switch set to "fast mode" RAID 0, striped) not "safe mode" (RAID 1, mirrored), and the manual clearly says if you move that switch (to mirror mode) you have to re-format the drive.

It doesn't show up on the desktop at the moment, only in Disk Utility, as a single volume waiting to be formatted (after which I notice things tend to show up on the desktop.) You sure I don't have to do anything? Shouldn't see two "drives"? And is there a value to having it formatted so it can be read by a Windows machine as well? Methinks yes - if you format it as Mac OS Extended (Journaled) won't it be unreadable by Windows?

[dnanian]

Right, so format it. You won't see two drives, just one - and you should partition it, with the Partition tab, as "GUID" for an Intel Mac or "Apple Partition Map" for Power PC>

Don't format for Windows -- if you do so, you won't be able to start up from the drive, and won't be able to use it with SuperDuper.

[galfromdownunder]

Originally Posted by dnanian

Right, so format it. You won't see two drives, just one - and you should partition it, with the Partition tab, as "GUID" for an Intel Mac or "Apple Partition Map" for Power PC>

Don't format for Windows -- if you do so, you won't be able to start up from the drive, and won't be able to use it with SuperDuper.

So let me get this reeeeally right - partition it into 2, call one say, RAID 1 and the other RAID 2, using "Mac OS Extended (Journaled)" as the format? Or just partition it into 1 and let the drive magically do it behind the scenes - if so, if there's ever a head crash on one of the drives, will you be able to call up the other drive to drag stuff off?

And, re the Windows question (although the only non-Mac choices of format seems to be "Unix File System" and "Free Space") - I am not planning to make this a bootable drive - I just want off-laptop data stored and mirrored.
I was simply going to copy data as it starts to clog up my laptop to the first partition (drive?) of the RAID, and presumeably it will automatically copy it to the second partition (drive?) - do I have that right?*

Since work uses a Windows/Linux environment, they were talking about hooking this box up to a computer there so I could drag stuff off of it using a hi-speed connection when I am road warrioring (which is 99% of the time). Will it still work?

Thanks for you help David, it won't be wasted - I predict a ton of people eventually asking the same questions...

(*I just realized I'm a bit out of line asking you all this, because clearly, I don't need to use Super Duper for this at all - since I am just copying data whenever I want to the RAID and it should automatically mirror - once I set the damn thing up correctly. Where I DO use Super Duper is to make a bootable clone of my laptop to a separate partitioned mobile drive - 2 'generations'. I imagine that if I decide in future to back up my laptop to the RAID as well, I'd have to save the RAID data somewhere else, partition it to add a clone partition, copy the data back, and from there on use Super Duper to make the bootable clone on the RAID, and the RAID would automatically mirror everything, right?).

[dnanian]

The RAID happens behind the scenes. You don't have to partition unless you need to have two volumes. If one drive fails, the drive will notify you and you'll replace the bad drive, but the data will be fine because it's 'duplicated' on two drives, thanks to RAID. All automatic.

You will not be able to use the drive with SuperDuper! if it's not HFS+. But if you want to use it otherwise, you can format it any way you'd like.