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RAID under Win 7, Disk Manager or Intel Rapid Storage?


Messerschmitt

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Any difference and pro and cons which I am using?

Updating my Intel Rapid Storage allowed me to see the whole 3TB HDD instead of just 746Gb.

Using the Intel Rapid Storage, the drive shows as 1 in Disk Manager as Primary. Using the Disk Manager, the 2 disks show together in red as mirrored volume, but individual if I open Intel Rapid Storage.

Or it makes no difference? What about portability? (if I have to take out the 2 HDD and use them on a different Win 7 computer)

 

Thanks

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If you have access to hardware (v)RAID, there is no reason to use the software equivalent.

You do not mention the RAID level, presuming RAID1 it is possible to boot a degraded disk in another machine, provided that machine has the same RAID controller and you connect it to the same SATA port. However, this is not a scenario that is considered in a pro/con argument regarding RAID. It is because such an action is only considered if there is a motherboard failure. Even so, I would not recommend using original degraded disks on another computer, instead use a copy of said disk. Hot swap in RAID is not for making member disks portable, but to allow for powered replacements. If it is a RAID0, you cannot use a degraded member-disk in any other system.

When RAID is enabled in the BIOS, you use the board software to create your array. The board software then presents this as a virtual disk volume, which Windows sees as only 1 device.

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Windows software RAIDs are interchangeable with any PC with the same OS version (there may be issues when moving between different Windows versions such as XP and 7). Hardware RAIDs are interchangeable only with PC with the same or compatible hardware RAID controllers. In any case you should move all disks of a RAID at once to avoid risk of data loss.

Edited by Yellow Horror
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Regarding the software (windows) vs hardware RAID, I've read a few articles saying I should really do software if I plan sticking to the same OS (in this case Win 7).

If the motherboard fails, I lose my array and my data since only that motherboard has access to the array. With windows, I can read my array in any computer or if I change any component in my computer.

So from this perspective I've decided to go with windows RAID. I've done RAID 1 and I have no concern on speed. It's purely to store movies, photos, etc. No application will run from these HDD's as I install those on my SSD where my OS is.

So now I was wondering if I did the right thing by using Disk Management in windows to create the array, vs using the Intel Rapid Storage Technology. Seems like the 2 don't communicate between them because now the IRST sees the 2 HDD's individually like there is no array. And when I used IRST before breaking the array and using Disk management, Disk Management saw the 2 HDD's individually as well with no signs that it knew it was part of array.

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Let's try to clear the matter.

Calling *anything* RAID without specifying its RAID level makes NO SENSE WHATSOEVER.

RAID 0 is NOT properly "RAID" as there is NO redundancy whatsoever, it is only a senseless way to (maybe) achieve very slight read/write speed increases (which actually happened only on some given configurations making use of slow, now obsolete, devices and connection buses) at the (real) cost of a definite increase in the risk of failure.

RAID 1 is actually "RAID", BUT it should be called simply "disk mirroring".

You can have disk mirroring BOTH via hardware and via software, in the case of Windows, software disk mirroring is one among the modes "dynamic disks" can be setup.

BUT at the end of the day, since the disks are actually mirrored, there are very little differences in practice on the contents of disks.

Basically each disk is (or should be) an exact mirror of the other.

In ordinary, day to day  operations, you will notice no differences using the one or the other.

When (if) disaster strikes and one of the two disks in a "mirrored" set fails, there are only a few slight differences, not really worth more than a thought.

In the case of a "hardware" mirrored set of two disks, you can *any time* take the one (or the other) and connect it to another PC and it will be immediately recognized as a "normal", "self standing" disk, and you will be able to access its contents "normally".

In the case of a "software" mirrored set of two disks, when you take the one (or the other) and connect it to another PC it won't be recognized "as is" and you will need to change the partition ID in the MBR from 42 to 07[1], and then it will be recognized as a "normal", "self standing" disk, and you will be able to access its contents "normally", even if a few sectors at the end of the disk (outside the normally accessed area) will contain "dynamic disk" settings data). 

The "hardware" mirrored set might be (slightly, you won't probably notice it) faster in operation.

Of course the "software" and "hardware" mirrored set settings "do not communicate" as - even if the end result is the same or very nearly the same - the way they work is different.

With hardware, you are essentially saying to the hard disk controller to write the data it receives to two different devices, with the software you are telling to the Operating System to write the data to two different connected devices.

Personally if I were to choose, I would prefer a hardware mirrored set (aka  RAID 1) over Dynamic Disks anytime, only because Dynamic Disks have historically given more problems, though the reason is not clear/straightforward, a possibility is that knowledgeable people (and with the available means to buy more costly hardware) chose either hardware mirroring  or never chose "RAID 1" while a vast number of less knowledgeable people (and/or without the means to buy a RAID controller) chose the "free" Dynamic Disks mirroring, hence there are very few reports of issues with hardware RAID 1 and some more with "Dynamic Disks".

 

jaclaz

 

 

 

[1] Never tried/checked how these disk behave if GPT and not MBR, but most probably there will be a similar issue of chainging partition ID.

 

 

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17 hours ago, Messerschmitt said:

If the motherboard fails, I lose my array and my data since only that motherboard has access to the array.

This is incorrect. If the motherboard fails, you can migrate the array to any other board (same model or different) as long as it has the same storage controller on the board. On the destination board, you would enable the RAID with no disks attached, shut it down. Then connect the disks from the other board to the same ports as the original board, boot the system and enter the RAID manager. Presuming that the disks themselves are sound, at the worst you'd have to do a rebuild. So it may not be a simple solution, but besides being able to read a single disk as jaclaz mentions, it is not a total loss to lose the board. But then again, this brings up the other point, RAID is not a backup solution. You lose the array, its a pain but you would have the backup, right? ;)

I will note that I have only done array migrations with a RAID1. I have never found RAID0 to be worth the risk for OS volumes and hasn't been a viable speed option since the advent of SSDs.

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