Questions to do with HD's in a Mac Pro and RAID

[Jebaloo]

See my post below this for most recent questions.

Hi, I've just ordered my MacPro and have been trying to work out how I'm going to keep my data safe. I've got too much data, so currently it's scattered all over the place and HD's of varying sizes, and then all of that is backed up on a 1TB Lacie Big Disk Extreme +

This HD has firewire 800 etc, but no eSATA.

I've just ordered my MacPro and am all out of money. I want to set up a great HD solution internally, but can't afford to be buying any more hard drives.

I just opened up my Lacie 1TB and saw that internally there are actually TWO drives (this probably isn't news to you but was to me).

They are both 500GB Baracuda 7200.10 and seem to have SATA power, and SATA Data, as well as a Jumper Block attachments.

(I've taken a photograph of the interior)

What I'm wondering is whether I could take these two HD's out of the Lacie enclosure and put them inside my MacPro to create a 'data security' RAID system.

Now I'm no RAID genius, and I'm sorry but I've tried, I still don't know which one is for me, but I'll quote a passage from Chase jarvis's Blog where he talks about his back-up solution.

"this is a giant hard drive (7TB) that writes (and retrieves) data seamlessly over 14 different drives in an array. This is fancy terminology that basically means that the drives all sync together to act like one drive, but in reality they're separate drives arranged in such a way that if one drive fails, the server can identify it and, upon replacing the defunct drive, re-create data that was on the dead drive."

He has an Apple XServe RAID, so I couldn't afford that, but...

What type of RAID would this be? And could I implement it on my MacPro on TWO hard drives without having to buy the RAID card? Would it be slower than having just one drive? Are the Baracuda drives in the Lacie HD any good?

Thank you so much!

 

[SilverL]

Your external drive basically acts in the same way.

You can create a volume - RAID 0 of 1TB internally if you plug in the two drives to your MacPro that will have the same effect.

 

[JesterJJZ]

I think you're talking about creating a RAID 1 mirror. Where both drives will keep the same information in the event one fails you don't lose anything.

 

[Jebaloo]

Thanks for the help.

So a RAID 1 is where everything is mirrored. So Two 500GB disks would give me 500Gb total space. Does the computer take any longer to read/write to a RAID 1, than just to a single disk?

If one disk fails, how do I know? If the disk corrupted some files, is there a risk that the system would mirror the corrupted files onto the second disk?

Is it possible to use time Machine to back up both of the RAID disks, and my main OS disk onto one other disk? Or does Time machine require one TM disk per HD that needs to be backed up?

Thanks for your help.

 

[Jebaloo]

Just wondering if anyone's got any answers.

CHEERS.

 

[edesignuk]

The 7TB array you mention will be a RAID5 array. For this you need a minimum of 3 drives, and you get the usable space of all but 1 of them. A RAID5 array allows for any 1 drive in the array to fail without you losing your data. Simply replace it and the data will be rebuilt based on what's on the other disks in the array. Obviously you only have 2 drives, so this is out of the question.

Your Lacie will have been using RAID0 to make the 2 x 500GB drives it actually houses appear to you as one. Do not pull those drives out of the Lacie, plant them in the Mac Pro and expect all your data to be there, it won't be. Often the way RAID works will differ slightly between different controllers. You can't just chop and change RAID arrays between totally different RAID management systems.

RAID1 mirrors data across 2 drives, so you get the usable space of 1. Not sure how OS X acts on a failure, but I imagine it just notifies you with some sort of alert.

 

[Jebaloo]

Thanks so much edesign. I was going to move the data off the drives first before placing them in the MacPro.

But what you're saying is that basically it will work, I just have to move my data first, and then set up a a RAID 1, using OSx software.

Does anyone understand the benefit of forking out for the RAID card, over just using the software available on the OS? I can't find anything on the Apple website about it.

 

[edesignuk]

Hardware RAID is always the better solution, but it comes at a cost. With hardware there are no overheads to the system since the hardware on the RAID card itself is doing all the work. Plus RAID cards normally have a battery on them so in the event of a power failure data in the process of being written to the array isn't lost.

What interface's do the drives in the Lacie use? If they're not SATA you can't use them.

 

[Jebaloo]

I believe that they are SATA. On the HD's there is a diagram with details the point on the hard drive were there are connections.

It mentions these terms: "SATA power, and SATA Data, as well as a Jumper Block"

Do you think that means that it would be suitable?

Do you know if you have to have on hard drive for each hard drive that you wish to have a time machine back-up for, or can you combine all macpro hard drives onto one Time Machine back-up?

Thanks for your advice re the raid card. I'm assuming it would be easy to install and implement?