Some questions about creating a hw/sw RAID 1 array

Hey there,

so, RAID is a pretty new topic for me. Just never needed it before.
However, I already own a 3TB Seagate HDD and recently got my hands on another one at a very low price.

I was thinking of building a RAID 1 array out of these two and use them mainly as storage devices (videos, music etc.).

So, my planned drive setup would be:
1x SSD for the OS (as it is now)
1x 500GB HDD for daylie stuff
2x 3TB HDDs as RAID 1 as pure storage

Now, here is what I just figured out while reading into all the RAID stuff:

1) I really don´t want to reinstall the OS and won´t have the time to do so in the near future, either. As far as I understand, just switching over to RAID in the BIOS would most probably to a blue screen when booting. I´ve only read a hand full of reports that were lucky enough and got it working.

2) I have a Asus Z87 Sabertooth mobo which means I have 6 Intel SATA ports and 2 ASMedia ports. But only the Intel ones seem to be able to do RAID.
Of course I could just hook up the SSD to the ASMedia controller and switch the Intel controller to RAID. This means, everything should work but since the ASMedia Controller is really slow, this is not really recommended.

3) So, the only possible solution would be a software RAID 1 which seem to fullfill my needs pretty good. I understand this is not really recommended for several reasons and therefore, I still have a few questions:
- I read in the FAQ that a software RAID setup would slow down the whole system although the OS isn´t on the RAID array. Could someone explain how and when exactly the system would be slower?
- What happens when I am doing a fresh install of the OS somewhere in the future (or a complete new OS for that matter)? Would I just see two independent drives that have the same files?

Is there any other way I did miss to set this up?

Thanks in advance.

EDIT: Almost forgot, just in theory what would happen if I do the following?
Connect the SSD to the ASMedia Controller and set it to boot from this drive (assuming the controller is bootable) and see if everything works.
Then switch the Intel Controller to RAID. Windows should still be able to boot and install the according RAID drivers, right?
Now, can´t I just connect the SSD to the Intel controller again and still be able to use the RAID drivers and boot from the SSD?
Or where is my error in reasoning?
10 answers Last reply
More about questions creating raid array
  1. when you switch to raid mode under bios, it wont corrupt your ssd data. So You can actually try it.

    If you put it in raid mode and you get bsod, you can just switch back to ahci or ide (whichever one it is) it should work normally again. So its worth a try to test to see if you get bsod, and if you don't, you all set!

    If you have your mode on ahci now, I don't think raid mode will give you bsod.

    I've never used software raid, but since it is software, its almost guaranteed to be slower, and prone to more issues, and I would not recommend it AT ALL especially if you are making a raid 1 array to save your data from being lost.

    EDit: actually it will give you bsod, but you can do this registry tweak and fix that :)
  2. Either one will be fine for Raid 1.

    Some people actually prefer software raid since it is hardware independant, meaning, you don't have to rebuild it if you upgrade your motherboard or controller in the future. You also won't lose anything if the controller fails.

    And the performance hit for software raid is miniscule.
  3. oczdude8 said:
    when you switch to raid mode under bios, it wont corrupt your ssd data. So You can actually try it.

    If you put it in raid mode and you get bsod, you can just switch back to ahci or ide (whichever one it is) it should work normally again. So its worth a try to test to see if you get bsod, and if you don't, you all set!

    Well, I didn´t ask this...but wanted to. So, thanks for reading my mind. ;)

    oczdude8 said:

    I've never used software raid, but since it is software, its almost guaranteed to be slower, and prone to more issues, and I would not recommend it AT ALL especially if you are making a raid 1 array to save your data from being lost.

    I don´t care that much for speed on my storage drive anyway. Well, as long it doesn´t like halve the speed or something.
    But yes, the "prone to more issues" part worries me.

    oczdude8 said:

    EDit: actually it will give you bsod, but you can do this registry tweak and fix that :)

    Didn´t know this works for IDE->RAID / AHCI->RAID, too.
    Only used this for IDE->AHCI once before.
    Will check it out lateron.

    Backup time now. ;)
  4. maddogfargo said:

    And the performance hit for software raid is miniscule.

    This includes overall performance, too?
    I´ve read some articles saying that a software raid would increase boot times (even if the OS isn´t on the RAID) and would put extra load on the CPU. Some even suggested to get more RAM when using software RAID which didn´t make any sense to me and was the reason why I stopped reading said article. ;)

    And what about what would happen when I switch over to another OS or a fresh install? Would I just see two drives with the same data?
  5. if your drives are still in raid, you would only see a single 3tb raid drive on the windows install screen, even though both drives have the same data.
  6. So many of your concerns depend on the particular RAID system you are using. I suspect you plan to use the "built-in RAID" on your mobo. So you REALLY should find the RAID Manual for your mobo. It is usually separate from your mobo manual. It may be a file on your mobo's CD of utilities, or you may have to find it from your mobo maker's website. Make SURE you get the manual for the mobo you have - not all RAID systems are the same!

    Let's back up a minute regarding "software RAID". This means a RAID control system that uses programming stored somewhere that is executed in your main CPU on the mobo, interacting with the relevant HDD controllers. This is how "software RAID" can slow your system - it uses CPU time. The impact with today's really fast CPU's is very small, but it exists. And note that this has little to do with the HDD's involved - it is use of CPU time that is the issue.

    There are three main types of software RAID. The first is a software package installed on your main HDD and loaded automatically for use in the background. You can buy such software, and Windows even comes with some.

    The second is actually stored in your mobo's BIOS chip as a set of routines to be used by the CPU to manage a RAID array connected to the mobo controllers. This is the "built-in RAID" on the mobo, and it IS a software RAID.

    The third is what comes on certain cheap RAID add-on cards. Some such cards come with a set of HDD controllers and you connect your RAID HDD's to the card's ports, not to the mobo. BUT the actual RAID programming is just stored on a BIOS extension chip on the card, too, and it is executed in your MOBO's CPU. It is still a software RAID.

    Finally, there is real Hardware RAID which takes up VERY little mobo resources. These come on add-on cards which contain HDD controller chips and ports (to which you attach your RAID drives), its own dedicated CPU and RAM, and its own BIOS. But in this case all the programming in this BIOS is executed on the board in its own CPU and using its own RAM and controllers, so it consumes very little main system resources. That's why true Hardware RAID can be faster, but it's also MUCH more expensive because the add-on board contains a lot of technology.

    And that's why many people will be satisfied to use virtually-free "built-in RAID" on the mobo and accept a very small hit on system performance.

    Be careful to distinguish between using a RAID array as a boot device, and using an array simply as a data storage device after you boot from a different NON-RAID drive. The issue centres around drivers and installation of the OS. There is no such thing as a "standard" RAID system, so Windows (and other OS's) does NOT come with its own built-in RAID device driver. Thus it cannot be installed on a RAID array, nor boot from it, unless you take particular steps to do the driver install as part of the OS's initial Install. (Yes, there is a simple way to do that.) But OP says his / her plan is that this RAID1 array will ONLY be used as a data storage device. That's much simpler. Basically, you will install your SSD and then Install Windows on it. Then you install the 500 GB HDD for the "Daily" stuff and Initialize that HDD (Partition and Format). When all that's done you install the pair of 3 TB HDD's and set up RAID.

    Now, this is where you really need to check the manuals both for your mobo and for your RAID system. For starters, as you have remarked, which SATA ports to use for this needs to be settled. Obviously, if you want to use free built-in RAID, you need to be using ports that are run by a chip that does RAID1. In my experience, I had to physically install the pair of HDD's, then go into BIOS Setup and specify that the ports used are to operate in RAID mode. If that clashes with your AHCI mode ports, that MIGHT be a problem. But, maybe not - some mobo makers actually use one unified device driver for both AHCI and RAID devices on one controller chip. Anyway, my next move was to boot and follow the POST prompts to enter the RAID Setup screens to actually Create the RAID1 array. NOTE that, in most cases I've seen, any HDD in the system that is NOT specifically assigned to a RAID array is NOT part of the RAID system, and operates just as a "normal" SATA or AHCI device. When you complete this initial RAID1 array creation, the machine may take quite a while to Initiate the array. This is rather like Partitioning and Formatting a single HDD, but it's specific to the RAID array. When all of that is finished the machine will boot up normally, but you still don't find the RAID1 array right away. However, it won't take long. In most cases the system will immediately recognize that a new device has been added - a RAID1 array - and it will search out on the boot HDD the proper device driver for it and install it in Windows. If that does not happen, you can check your mobo manual for where to find the proper RAID driver and how to Install it yourself. From now on, every time Windows boots up from your SSD, it also will load the RAID array driver along with about 40 other device drivers so that, when booting is complete, the RAID1 array shows up in My Computer as one large "drive".

    Note that I said this is MY experience. I had to install the hardware, configure BIOS to use the drives as RAID units, use the RAID Management screens to Create the RAID array, and FINALLY get the RAID driver installed - it would not allow me to install the RAID driver before the RAID array actually existed. Your system may be different, OP, so make sure to read the mobo AND RAID Manuals.

    Now we come to something that is not solely a RAID issue. You want to use pair of 3TB HDD's for this. This brings up at least three items to deal with, all because you want to use HDD's over 2 TB.

    1. Microsoft's policy is that they only support the use of HDD's over 2 TB in the 64-bit versions of their Windows products. So you MUST install the 64-bit version of whatever Windows you plan to use.

    2. Check the capability of your mobo to handle HDD's over 2 TB. And make sure to check for all the SATA ports, not just the "main" ones. You MAY not need the new UEFI support in BIOS because you do not plan to BOOT from these large HDD's, but I don't know.

    3. Check specifically whether your mobo's ports and "built-in RAID" can work with drives over 2 TB. You'd hate to find the the ports can handle large drives, but the RAID software in BIOS cannot.
  7. I want to say that raid is not a backup. If you want the other drive to be a backup of the primary then use it as that: a backup drive. Schedule backups as you see fit (hourly, daily, weekly...) and save them to the new 3tb.

    In raid1 if you, a virus, an accident... wipe a crucial file of the primary drive - its automatically gone from the secondary drive too. If you don't notice it for a week then even recovery software might not be able to help you. With a nice backup system, you don't care since you can recover the file any time you want.

    important data should always be stored in several locations, one preferably should be offsite in case something happens to your place.
  8. Yup, I know.

    So, I just found a super easy method for switching from AHCI to RAID:
    There's a MUCH **MUCH** simpler solution available now. What a relief.

    1) Visit and go to KB article 922976
    2) Download (and save) the "Fixer" app there
    3) Use the fixer just before any reboot that involves any of the following:
    - switch between AHCI/RAID/IDE modes
    - reboot after uninstalling Intel IRST/RSTe Drivers

    This "fixit" restores generic Microsoft drivers of ALL kinds on the next reboot. NICE!

    Works like a charm.
  9. Ok, scratch that.

    It did NOT work.
    After the second reboot, the booting took about tripple the time, one HDD was way underperforming and the 3TB HDD wasn´t recognized anymore and I couldn´t fix it.
  10. If anyone is interested: I have now set it up as a completely software controlled RAID 1.
    Works great and suits my needs.

    Thanks again for all the replies.
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