Our current production server has 6 hd's in a RAID 10 array. Technically it's not RAID, but the new Windows Storage Spaces feature in Windows Server 2012 (think software-RAID). These six are used for storing VM servers only, the OS boots from a 60 GB SSD.

Now when I was first building this server, Storage Spaces gives you 2 different options for creating a RAID 10 array - either using a 2-way mirror or a 3-way mirror. I chose a 3-way mirror, and I'll say why: at the build time, it was unclear whether there was going to be any suitable backup available (small business budget restrictions). Also, I chose cheap-cheap SATA drives for the array (for the same reason).

I did end up acquired a nice 2 TB External backup drive from the old servers. Each of the six HD's in the new server are 500 GB. But with a 3-way mirror, I'm actually losing 4 of the 6 drives to redundancy, giving me 1 TB total of usable space. Now that we have a daily backup in place, I'd like to restructure this array to a 2-way mirror for DB performance (writes are SLOW), so instead we lose only 3 of the 6 drives to redundancy and get 1.5 TB of total space. I'm wondering the best way to do this.

My idea was to ensure last night's backup completed successfully, delete all the data from the drives and destroy the array; then we use the 6 drives to build a new array (this time with 2-way mirror) and restore the data from the backup. Would this work? Does anybody have experience with a Windows Storage Spaces backup used like this yet? This is now a production server, and I have no dev servers to play with, so I really need to get this right or risk losing all of the company's data ;(

Is there any better way to restructure said array?


This should work. The first question I would ask is have you done a test restore of your data. At least part of it. Worst case scenario you should be able to use the data on you back up disk and it would probably be a good idea to create a share from that and have one of your user do a test to verify that your that data is actually usable.

  • So what I'm getting is it really comes down to how robust my backup solution is right? In that case, it's the Windows Server Backup that came OOTB with Server 2012, and a 2 TB external USB drive. I checked the drive and it looks like a single 3.5" SATA drive doing business in there, so for all I know it's crap. However the Win Server Backup seems pretty decent, right now I've got 24 backups, most completed successfully, about 1/3 completed with warnings (I think because VM's were still running?) Anyway, even if one restore fails I think I should be good with my other multiple backups, correct? – IT Bear Jul 22 '13 at 17:20
  • As soon as you designate a drive as backup in WinServer Backup it no longer makes that drive visible, kinda takes over that drive and hides it. This makes that test you suggested test more difficult, I would have to force it into visibility before even checking if I could view the files in it individually, even still I don't know if they're locked away in some .bak file. I'm checking MS documentation on that now... – IT Bear Jul 22 '13 at 17:30
  • My self. I would really want a known good backup. It does really come down to how robust you backup solution is and the only way to determine if the backup is good is to do a restore. If your files are opend or the VM's are running those backups may not actually be usable. Typically validation is part of a backup solution (Well actually it is best practice). You really need that smoke test to know what you have is good. Perhaps get one more disk, do a full, then do a couple restores to test. – emptyshell Jul 25 '13 at 1:46

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