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Raid 11?

P

pyrogx2000

Limp Gawd
Joined
Dec 18, 2001
Messages
176
I have a 1TB drive mirrored to a 1TB drive.

WIth a regular Intel desktop board with ICH10R (there are available ports for this),Is this possible?:

Buy 2 more 1TB drives and create another seperate 1TB mirror,
and then have mirrored Raid 1 arrays? (2 arrays of 2 disks, 4 disks total)

Is this called raid 11?
 
You want 2 separate RAID 1 arrays right? If you have two RAID 1 arrays, you just have two RAID 1 arrays, it's not called RAID 11. Or are you trying to mirror the mirrored array?
 
Yes I want to mirror the mirrored array. I want one volume mirrored across 4 disks technically.

I heard you cant have more than 2 disks in a raid 1 stack, so thats out.
 
Does your motherboard support Raid 5? If so, why not run that instead? With 2 Raid 1 array's, you would lose 2 drives, with Raid 5, you would only lose 1 drive out of 4.
 
Raid5 has parity calculation overhead whereas raid1 has no calculating involved. This is an interesting idea. I'll grab a spare adaptec 5805 and see if it'll mirror a mirrored array. I'd guess if it doesn't, then onboard raid isn't going to be more capable.

The other option is two raid1's and use something like Acronis secure zone to image one to the other on a schedule (hourly?).
 
I guess so, but I had a bad experience when 2 drives out of 4 failed in a raid 5 stack. I want the super redundancy, or at the very least, the maximum amount of time bought before I notice a drive is gone. The raid volume I want to protect is on another computer and I don't check it often.
I was thinking of buying a Western Digital 2TB Mirror edition, and backing up differentially to it, but then came up with the idea of mirroring the mirror so that its all instant.
 
pyrogx2000 said:
Yes I want to mirror the mirrored array. I want one volume mirrored across 4 disks technically.

I heard you cant have more than 2 disks in a raid 1 stack, so thats out.
Click to expand...

This is raid1.

Linux mdadm allows you to have N devices, all mirrored like in Raid1.
 
I can't find a way to do it on a 5805 but it sounds more like you just need a raid card that does email notification when a drive dies. Then just do two drives in raid1 and the second one goes out, you get an email. The odds of both dying within minutes/hours of each other is astronomical on your small scale.

There's always hotspare options as well.
 
I understand the ability of the managment app for the card giving me a notification email.

However! This machine is on a seperate network, not connected to the internet, for isolation purposes. Anyone wishing to connect to it needs a gigabit network card which runs over a switch. Is there any way it could send me a message somehow?

It's running XP 64 Bit.
 
does your controller support RAID 10, i would go that route personally.
 
Do you think having 2 separate raid 1 volumes with a backup utility (differential backup) would work well?

Volume has a bunch of large files for storage that dont get edited or moved often.
 
thebeephaha said:
Make two hardware RAID1's and software mirror them???
Click to expand...

This seems like the simplest answer if my original idea isn't possible! Thanks :)
I forgot windows could do this since I was always making only one array managed by the card/motherboard!
 
Wouldnt just a single Raid1 with 4 disk work?
It should just use four disk instead of two.
Theres no rule that Raid1 can only use 2 disk.
 
nitrobass24 said:
Wouldnt just a single Raid1 with 4 disk work?
It should just use four disk instead of two.
Theres no rule that Raid1 can only use 2 disk.
Click to expand...

Was thinking of doing this but didn't know if it was possible. Will ICH10R on a desktop board let me add more than 2 hard drives to a RAID 1 array? What if the array is already made, will it let me add them on?
 
pyrogx2000 said:
Was thinking of doing this but didn't know if it was possible. Will ICH10R on a desktop board let me add more than 2 hard drives to a RAID 1 array? What if the array is already made, will it let me add them on?
Click to expand...

It should let you do more than 2 hard drives.

As for it letting you expand an existing Raid1 array i dont know.
 
nitrobass24 said:
Wouldnt just a single Raid1 with 4 disk work?
It should just use four disk instead of two.
Theres no rule that Raid1 can only use 2 disk.
Click to expand...

It seems like it would be this simple. Maybe ICH10R can do this but my adaptec 5805, a hardware raid card I had thought was one of the top of the line, does not give raid1 as an option once more than 2 disks are selected during array creation.
 
You need a nested function to do 1+1 or you can do raid 51, alternatively you can also look at 50 and 60 as it allows for serious drive loss.
 
you said 2 disk losses?... how about regular RAID 6? I don't see any advantage to RAID 11 at all...

How about raid 5 with a hotspare? That would basically allow you to have a disk rebuild immidiately if you lost one... any maybe even regular raid 1 with 2 hotspares... that is definetely an odd setup though so I wouldn't be surprised if you had a hard time finding a controller to support it. Software might be the way to go.

Does WHS support triplication? that would be 3 disks all mirrored... I don't know a thing about WHS though.
 
pyrogx2000 said:
Yes I want to mirror the mirrored array. I want one volume mirrored across 4 disks technically.

I heard you cant have more than 2 disks in a raid 1 stack, so thats out.
Click to expand...

Assuming that what a few others here have said is true, that you can create a RAID1 array with more than 2 disks, you could simply do a 3 disk RAID1. This would give you 2 backups of your original. You would need to have 3 drives fail before the rebuild completed in order to lose data. If you really want 3 backups (4 simultaneous failures needed for data loss), then I assume a RAID1 of 2 RAID1's or just a 4 disk RAID1 (however you get it set up to work) would essentially be the same thing.

For multiple disks, RAID6 like a few others have said. It's RAID5 plus an extra parity disk, so it can handle 2 simultaneous failures. I suppose a RAID6 with one data disk and two parity disks would be functionally equivalent to a 3 disk RAID1, but with added parity computation overhead. Though it seems like having the other drives storing parity rather than just mirroring the data would change the usage pattern from the original, and hopefully a failure wouldn't happen at the exact same time.

hmchk said:
How about raid 5 with a hotspare? That would basically allow you to have a disk rebuild immidiately if you lost one...
Click to expand...

The problem is that the extra work of the rebuild can trigger another drive failure before it's done rebuilding. If you're using perfectly matched drives, there's more chance that more than one will fail very close to each other. As drives are getting bigger, the rebuild takes longer, which gives a bigger window for a second failure to cause huge problems. That's where RAID6 comes in.

And to once again point out the obvious, RAID helps to avoid downtime, but is not a substitute for backups.

P.S. RAID helps to avoid downtime, but is not a substitute for backups.
 
InvisiBill said:
And to once again point out the obvious, RAID helps to avoid downtime, but is not a substitute for backups.

P.S. RAID helps to avoid downtime, but is not a substitute for backups.
Click to expand...

given what the OP said "PC not checked regularly and I want to maximize the time until it goes down", so RAID seems like a perfectly fine solution for his challenge.
 
The ICH10R supports hot spares. You can have two drives mirrored, Then designate additional drives has hot spares. When one failes it automatically rebuilds the volume on one of the spare drives.

From the Matix Storage Manual:
TABLE 4. OVERVIEW OF SUPPORTING STORAGE MANAGEMENT FEATURES
RAID Spare Marks one or more hard drives as the destination for automatic rebuilds.
Click to expand...
 
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