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Mirroring the OS


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Well, here goes my first post!


I would like some advice please on how or even if to mirror my OS drive in WHS 2011. My setup is as follows.


HP Microserver N40L with 8gb ram and modded bios

250gb 2.5" drive under the ODD bay which has the OS on it

2x 2gb WD red drives in two of the bays for data which are mirrored

1x 3gb WD red drive in another bay which is used for internal backups for the data and OS


I also have an external drive which I back up to every two weeks and keep offsite.


So I have one spare bay and my thoughts were to put in a 250gb drive to mirror the OS for redundancy purposes

as the server is used extensively by the family and hence any downtime is a pain and I don't have a lot of spare time to rebuild things.


I have tried to read some material on the web but I think it has confused me further!!


I would welcome some advice on how to mirror the OS drive and whether that is a good thing to do and will protect me if one of the OS drives fails.


Thanks you.



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Top Posters In This Topic

  • jmwills


  • ikon


  • Joe_Miner


  • Carpediem


Hi Joe

Thanks for your response. I have introduced myself as you suggested so thanks for that.


In relation to your other two links,for which I'm grateful to you for, my OS at the momenet is connected via the onboard SATA cable that most users

would use for the ODD. Would setting Optimal Defaults in the BIOS affect this?


Is doing the RAID through the BIOS better than doing it via disk manager?


Lastly, is it a wise thing to do to mirror the OS?


Thanks in anticipation. :D



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Mirroring the OS is a safe way to be redundant.  If it were me, I would mirror the OS through he BIOS and Data from the OS.

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Hi Carpediem! 


Unfortunately, setting Optimal Defaults will reverse any changes you made after you did the BIOS-MOD and you’ll only be able to do RAID with the 4 drives in the Drive Cage – in the Video/write-up I did a RAID0, set up on the System Board, on two VR’s in Slots 1 & 2 of the cage and after I loaded the OS I did a SW (via Disk Manager) RAID1 on my Data Drives in Slots 3&4 of the cage.  You could still use the ODD SATA Port and the eSATA port but they will be in IDE emulation (with the inherent slower speed cap). 


Personally, doing a RAID1 or RAID0 of the OS I would do it in HW and not SW (Disk Manager) but there are folk in the Forums who have done it in SW (check out Jason’s setup for instance).


Yes & No.  Best practice for a server in a business environment would be to RAID1 the OS drive to provide better reliability/resiliency and greater “up” time.  Many have done what HSS-Dave did in his WHS-2011 build and used an Icy Dock to RAID1 the OS drives.

See also Migration to WHS-2011 and Dual RAID Setup on Windows Home Server 2011 and Adding Drives to a RAID5 Array


In my own case I do not RAID1 my OS drive because my focus is only on preserving my data – I can tolerate down time if my OS drive fails and I have to reinstall.  In my own tests when I was upgrading my OS drives I found I could reinstall the OS on a new drive and link up my shares in an afternoon’s work – but that’s just me.


In the write-up earlier, I did RAID0 my OS drive on a build I took to the Meetup because it's faster and a lot more fun -- but it's definitely not a best practice :)

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Joe, jmwills


Thank you both for your prompt and informative replies.


In short then, if I want to mirror my OS in its current configuration I will have to use software (Disk Manager)

as if I use the BIOS I will have to use up two of the bay drives and cancel out the advantages of the Modded bios? Is that correct?


Joe, you mention Jason's set up. How do I see that please? :rolleyes:

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JM, so he can't mirror 2 non-cage-mounted drives using the BIOS, whether it's the stock version or a mod?


Carpediem, you could consider using a small 2-port RAID card such as the ones from StarTech.com.

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I'm really grateful to you all for your responses.

Having read through everything last night I decided to mirror the OS using disk manager.

I chose this for two reasons:

  1. I have had my data disks in this configuration for over a year and not had a problem
  2. I didn't want to lose the changes I made to the Modded bios from JM's excellent post as I feel these were more important to me due to my set up.

I bit the bullet last night and Mirrored the OS which took about 20mins in total. I found this infomrative article which provided a little more information for me.



The mirror worked fine and I then re-booted the system to ensure that there were not problems. So this all went well having read all your helpful suggestions and the guide at techotopia.


I only found a small issue in the morning which I will quickly explain here in the hope it may help someone else.

I have an e-mail alert in the morning informing me that the Back Up had failed. I RDP'd into the server and started another backup

which also failed. When I checked the details, it had backed up my data but not the operating system.


To fix this, all I did was run the Customize Backup for the server wizard. I didn't change anything as all the settings were as I wanted them.

Once the wizard had finished, I ran a backup and it worked first time. So running the wizard seemend to clear whatever was preventing

the server backing up.


Thanks again to you all for your help. No doubt I will post again when I get more time to tinker. :lol:

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I'm really glad to hear it's all working out. IMHO, there are 2 things left to do:

  1. test recovering a broken mirror.
  2. test restoring the OS from a backup.

It's great for us all to harden our systems like this but, unless we actually test the features, we can never be sure they will work when really needed.

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