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Windows 7: Mirror is useless if first drive fails

10 Sep 2009   #1
thardie

Windows 7 x64
 
 
Mirror is useless if first drive fails

So, I installed windows 7 ultimate with 2 drives. I'm running on a MB with an AHCI (ICH10R SATA controller - No extra drivers needed. Win7 sees the drives fine during install). It did the normal thing on 1 drive of making a system reserved partition with all the bootmgr and BCD stuff. I'm not able to mirror it. But, I was able to mirror the main installation partition.

Forward a few days - Drive 1 (the one with the "System" (BCD and bootmgr) and the main installlation) dies. Now I have another drive with just the main installation. Of course, I can't boot anymore.

OK, I think - I'll add the missing boot files to the still working drive. I boot the install CD, go into a CMD prompt. Break the mirror, and make the working partition standalone. I copy bootmgr onto the drive's root, create a "Boot" folder. A run diskpart and mark the partition as active. I run bootrec/rebuildbcd (which works and finds my installation), bootrec/fixmbr (also works) and bootrec/fixboot (also works). Great, so now I can boot?

Wrong. I just get a blinking cursor on trying to boot. I've run through the GUI repair, and still no go. I cannot figure out what's missing.

So, the bottom line is - If you're using a mirror thinking you're safe - Think again. Your data will be safe, but forget ever booting that installation again (


My System SpecsSystem Spec
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10 Sep 2009   #2
pbcopter

Windows 7 Ultimate x64 SP1, Windows 8.1 Pro x64, Windows 10 Pro x64
 
 

In order to actually have a mirror you must set the BIOS to RAID and create a RAID1 array with the two drives. Then everything is duplicated.
My System SpecsSystem Spec
10 Sep 2009   #3
thardie

Windows 7 x64
 
 

Quote   Quote: Originally Posted by pbcopter View Post
In order to actually have a mirror you must set the BIOS to RAID and create a RAID1 array with the two drives. Then everything is duplicated.
Yes, I know that would work, but I've had those cheap motherboard RAID systems dump my whole array for no reason, that I'd rather trust windows mirroring than the motherboard controllers.

That also doesn't fix my current situation. Thanks anyway.

Terry
My System SpecsSystem Spec
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10 Sep 2009   #4
pbcopter

Windows 7 Ultimate x64 SP1, Windows 8.1 Pro x64, Windows 10 Pro x64
 
 

I'm sorry I'm not that familiar with using the software mirror. I would have thought that the repair option of the DVD would have fixed the start up for you.

Paul
My System SpecsSystem Spec
10 Sep 2009   #5
Tews

64-bit Windows 8.1 Pro
 
 

Sounds like a clean install is in order....
My System SpecsSystem Spec
10 Sep 2009   #6
thardie

Windows 7 x64
 
 

Quote   Quote: Originally Posted by Tews View Post
Sounds like a clean install is in order....
Of course, that would work, but I'm not going to be the last person to use a mirror and expect my data to be safe. Seems like a major architectural flaw making the mirroring of boot drives useless.

What's really infuriating about this is I get no boot loader screen. No error, nothing. Just stops.

I've also tried installing the bootmgr set with bcdboot. I've also tried using bootsect to write the boot sectors instead of bootrec. Still no go. It's very odd.
My System SpecsSystem Spec
11 Sep 2009   #7
DeaconFrost

Windows 7 Ultimate x64 SP1
 
 

There's been a rule on computing for many years now that states, "Never let software do the job of hardware". Software RAID is FAR less reliable than hardware RAID, even when done with a motherboard's controllers, as opposed to a dedicated one. RAID on a desktop also has little value, and has never been a method of protecting or backing up your data. Consider even a smaller example. If you accidently delete a file on a mirrored array....that file is gone.

Do yourself a favor. If you care about the data on those drives, ditch RAID altogether and get an externa USB drive. Use something like Acronis (whole system) or SyncToy (files and directories) to keep your data backed up to the USB drive. Not only is is safer, but it can be transferred to another computer for easy recovery.
My System SpecsSystem Spec
11 Sep 2009   #8
zigzag3143

Win 8 Release candidate 8400
 
 

RAID on a desktop gives a sense of security when in fact no added protection is gained. There is always going to be a single point of failure on a desktop that if it fails you lose the data. the only way to prevent it is to have 2-blades, with 2 controllers each, with 4 or more drives, on seperate power, in seperate locations. Even then if a cpu goes your hosed.

You are more likely to be aware of the danger of losing data without the false sense of security, and backup accordingly.

Backup, Backup, Backup. Then backup the backups

Ken
My System SpecsSystem Spec
11 Sep 2009   #9
iseeuu

 
 

Quote   Quote: Originally Posted by DeaconFrost View Post
There's been a rule on computing for many years now that states, "Never let software do the job of hardware". Software RAID is FAR less reliable than hardware RAID, even when done with a motherboard's controllers, as opposed to a dedicated one. RAID on a desktop also has little value, and has never been a method of protecting or backing up your data. Consider even a smaller example. If you accidently delete a file on a mirrored array....that file is gone.

Do yourself a favor. If you care about the data on those drives, ditch RAID altogether and get an externa USB drive. Use something like Acronis (whole system) or SyncToy (files and directories) to keep your data backed up to the USB drive. Not only is is safer, but it can be transferred to another computer for easy recovery.
Well said. I also agree wholeheartedly. My experience with RAID is that creating a bootable RAID array is not an easy thing to do and presents its own risks ie: what to do when the array fails and there is no OS to boot to fix the problem.

The software RAID included with many motherboards these days can be another layer in a backup strategy, but it is not the ultimate solution. Rather, locate your OS on its own drive, and save back-ups and files on a mirrored array. If one drive fails stick a new one in and let the software "rebuild" your data. But note you would still have to do the regular back-ups of your system which is what I think some are trying to avoid with a RAID setup. They anticipate a bullet-proof RAID mirror where they do not have to do anything except replace a hard drive occasionally. An external USB drive backup strategy is actually less expensive and safer.

Another note on this type of raid setup: The life expectancy of identical hard drives purchased from the same vendor on the same date may also be identical (their life expectancy that is), meaning both drives may fail with in a short time of each other if not at the same time. One way around this is to get different brands of drives. It also makes identifying a drive in an array easier.

thardie, your situation does not appear to be any kind of design flaw. By Windows mirror I assume you mean using the image creating utility in Windows 7? It appears the image is in tact on the remaining drive? If so that "image" is not designed for booting. It is designed so that you can now purchase a replacement hard drive and use the 7 install DVD to restore that image to your new hard drive.

Good luck!

Robert
My System SpecsSystem Spec
21 Jan 2010   #10
dsula

windows 7
 
 

The purpose of software raid is, that you become independent of hardware. I used to do hardware raid. Pain in the ass when after 3 years your mainboard fails and you can't get a replacement witht he same raid chipset. Linux does software raid 1 the way it's supposed to be. A complete mirror and you can take away any drive anytime and still boot the system. I was hoping windows 7 would do the same. However it looks's like it doesn't.
My System SpecsSystem Spec
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 Mirror is useless if first drive fails




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