Expand RAID 5 array on Dell Perc 6/i

   I have a Dell r710 with the Perc 6/i controller.  I currently have a RAID 0 with one drive for the operating system and a RAID 5 with three drives for data.  They are 36 GB drives.  This was originally supposed to be an IT utility system for lab testing but has since become a semi-production system.  We run Hyper-V on it with some already configured VMs.  Well, we want to increase the drive space used in the quickest manner possible.  We bought some new drives for the data array and now I need to find the best way to move to the new drives.  Would it be possible to replace one 36 drive at a time, allow the array to rebuild to each drive before moving on to the next one, and then expanding the logical drive to use the remaining space on the larger drives?  Also, once that is done, can I then add additional drives to the array (we also have additional drive slots open we would like to use.  

My goal is to do this without any downtime for my VMs.  Not that they couldn't be down overnight, but rather the time it would take to copy them off and then back.
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PowerEdgeTechIT ConsultantCommented:
Replacing the drives one at a time will not work.  Once each drive finished rebuilding, your array would still be the same size.  As there is no way to automatically OR manually "expand" the Virtual Disk, you would really only have one option at that point:  Create a new RAID 5 across the disks, giving you a new "disk" in Windows and a new drive/partition.

The "best" way would be to backup/image the data, put your larger drives in, configure RAID 5, then restore data to it.

Another way - if you have additional slots in the machine - is simply configure the new drives in the machine, then copy/image the data from the smaller array to the larger array.

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And even if it did "work" to the extent that the arrays automatically expanded, you still put yourself at risk of data loss because there is absolutely no way that you can prevent losing another disk, or even just get a read error while you are spending a day expanding.   It is foolish to even go down that path even if it did work.

The PERC will do background initialization, so the moment you build the array you can begin copying to it.  If this system is important enough where minutes really mean money, then you could probably get the cloning done in a few minutes of downtime by
  * Disable VM from auto start after boot
  * power off
  * add a SSD, connect to motherboard port's, leave case open if you have to.
  * Power on
  * copy VM to SSD
  * Then at this point you could run the VM on the SSD if you want to by reconfiguring temporarily, you still have the original data and a SSD is going to be more reliable than some 36GB drives that are probably pushing 6 years of age.
At this point you can put in the replacement drives and let it initialize the new disks, and whenever you are ready you can shut down the VM and copy.  Going from SSD to the R5 will only take a few minutes.   This way, worst that can happen is if you have hardware failure, you will have a backup that is as many minutes old as the number of minutes it has been turned on.  

Personally, you will be much better off if you build a RAID1 to replace the VM.  A 3-disk R5 in long run is less reliable as a 2-disk R1. That is because each disk will be doing over 50% more I/O
lbicher56Author Commented:
I am accepting both responses as solutions as they are both reasonable and both confirmed my suspicions.
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