I have a Windows 2008 Standard server. It currently has 3x 1TB drives in Software RAID 5 (as per the Disk Management Console).

I need to add another 2x 1TB drives.

Is there any way to add these two disks into the existing RAID 5 array without any data loss, or without having to back everything up (We don't have that much extra free storage avaliable on short notice)?

  • 4
    You really need to back everything up, even if this can be done non-destructively. Jun 3, 2009 at 1:02
  • @Even Anderson: I agree completely. @Farseeker: With 2TB internal drives for ~$250; external, ~$300; and NAS, <$1000, that data must not be too valuable. I suggest format C: will be quicker than an online resize.
    – derobert
    Jun 3, 2009 at 5:01
  • @derobert, the data is valuable, but it is at a church installation where budget is severly limited and they run pretty much on donations. We have backups of the absolute critical data, offsite, of course, and honestly I'm looking for a quick way out because I don't have many hours to donate to this task (volunteer). Jun 3, 2009 at 7:38

4 Answers 4


It would appear that the short answer is "No" - a Windows RAID-5 array cannot be expanded (safely) once it has been made. So make sure you get enough headroom in it in the first place, or buy a proper RAID controller that supports online expansion!


I think you could add the disks to the array and then use something like Partition Magic (or Partimage) to increase the size of the partition on the array of disks.

Regardless, you need a backup. RAID is not a backup strategy (as has been written many times in this site). Schedule the system downtime for immediately after the backup has completed, and be ready to restore.

  • If you do get the RAID set expanded, Diskpart can be used to extend the partition without the need for a 3rd party tool (try 'help extend' in diskpart)
    – Froosh
    Jun 3, 2009 at 1:53
  • Hmm, but how do you actually go about adding the disks to the array? Jun 3, 2009 at 23:29
  • With our hardware RAID, one attaches the drive to the system and then uses the RAID management interface to add the disks to the array.
    – pcapademic
    Jun 3, 2009 at 23:42

I had the same problem with Windows Server 2003 (not able to expand a Windows RAID-5 array),

I ended up writing a program that does the trick (expand an NTFS partition on a dynamic RAID-5 volume, it also has the ability to recover from a drive failure during the expansion process)

The on-disk structure for Server 2003 and 2008 is the same, however my program operates differently under Windows Server 2008 and takes all the dynamic disks offline (necessary for direct disk access) instead of locking the disks and volumes.

You should test it on a smaller scale before using it. Be sure to back up all of your important data.

Both my program (Dynamic Disk Partitioner) and its source code are available here


Does it need to be part of the same drive?

Could you add those two drives as a RAID 1 and mount them as an E drive?

Then move some of the file shares over there to help balance the usage.

Thats what I did the last time I had to add more space to a file server. Safer then messing with existing drives.

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