Stripe and Mirror on the same two drives?

September 22, 2011 at 13:28:11
Specs: Macintosh 10.6.8, Xeon 2.66GHz-Quad 7GB
I am partioning two drives in my MacPro. The top partition is a striped raid with the OS and the bottom partition is a mirror raid with the majority of the data. This seems to work quite well, but I am interested in hearing if there is any pontetial difficulties or issues that I have not forseen. Perhaps maybe a conflict when there is data being moved on the stripe and the mirror at the same time? I want to set this up on my partners machine also and need to be sure that her business will survive my optimism.

Anyone have an opinion as to whether or not this is a good idea or bad? And why?

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#1
September 22, 2011 at 17:27:37
Silly at best. Pick one or the other.You select a raid for either speed or data security.

Data security is a whole set of practices. It doesn't mean you don't have to make regular backups to a remote media.

1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.


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#2
September 22, 2011 at 19:04:21
Issues not seen.....when it comes to back ups the thing to keep in mind is; "Is there a single point of failure?" in your case there are.......the house burns down taking the computer and it's contents.....a power surge fries the board and everything attached to it.....hence off site back ups or remote back ups. A 0+1 striped mirror on two drives is an inexpensive choice being sure to make backups....automating the backup is preferable as leaving it for someone to remember tends not to be reliable.

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#3
September 22, 2011 at 19:51:37
I guess that I asked for it. I posted this on several forums and the immediate reaction is that Mirrors are not the same as backup. Sorry for the lack of clarity.

We have plenty of redundant backup on-site and off.

What I am interested in is are there any unforeseen issue with this setup?

Will it fail?
Will it hurt the Hard Drive?
Will the data get corrupted?
Will the mirror make the Stripe so it bogs down or otherwise doesn't function properly?
Or whatever else might make it untenable??

Thanks, Tripp


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#4
September 23, 2011 at 06:41:41
I would have done a 0+1 striped mirror for the entirety of both drives. With a normal mirror...if a hard drive dies, you simply yank it out and put in another drive....the mirror rebuilds the raid array on the new drive and copies the data making the mirror whole again. In the case you have described if a hard drive fails and is replaced the operating system partition will not be recreated. 0+1....the striping enhances the speed and mirroring gives the fault tolerance......maybe I am not reading this correctly, but I fail to see the advantage of having the operating system on separate non redundant partitions? If there was only one drive that would make sense.

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#5
September 23, 2011 at 10:18:43
With the low cost of drives it would make sense just to use 4 drives, the cost would be maybe $100. more, which for a business would be insignificant and the advantages far greater.

You have to be a little bit crazy to keep you from going insane.


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#6
September 23, 2011 at 13:43:41
I do not understand how you can do 0+1 raid on only two drives?
Can you tell me how it is done?

Thanks


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#7
September 23, 2011 at 13:45:17
Fingers,
All the drive bays are full and hence we cannot do as you suggest.
Thanks

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#8
September 23, 2011 at 14:11:57
If I made regular backups then I's use my hardware raid controller to create a striped array. If I didn't have a hardware based raid then I wouldn't fool with it at all.

Raid arrays don't generally wear out drives or damage then as such nor do they create data loss. This does make some assumptions.

I just don't get your reasons for this odd setup. Raid 0+1 may be a solution but takes a lot of room for a small gain.

1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.


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#9
September 23, 2011 at 19:09:11
PCI or PCIe SATA RAID card would give you the additional ports.

You have to be a little bit crazy to keep you from going insane.


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