RAID1 expansion?

[Golfcart]

Is it possible to extend the volume of a RAID1 array by replacing the disks incrementally?

I have a client that needs more storage for a mysql database on a Dell R440 with 4 drive bays and all using the hardware RAID controller. Bays A and B are the OS disks in RAID 1 and have no issues. Bays C and D, also RAID1, are the mysql storage location and only have 1TB of storage but is quickly approaching storage limits at only 12% free space. The needs are to expand the mysql storage to 4TB but keep the data from the existing disks and not exceed 1 hour of server downtime. 
Can I replace the drive in bay C with a 4TB disk and let it rebuild the mirror of D with the limit of 1 TB then replace D with another 4 TB disk and let it rebuild the mirror again. Once this completes could I then extend the volume to allow the additional space to be used and if do is this done from windows disk manager or from the raid controller during boot options

[johnt]

If you are only talking about less than 1 TB of storage, just move the data to another drive temporarily, replace bays C and D with larger drives, and copy the data back to the new RAID.

 

No matter what you do, you should create a separate back up of the data before toying with drives in a RAID configuration.

[Golfcart]

@johnt Thanks for the reply.

The server runs a full backup daily at midnight to a NAS so we would never lose more than 24 hours of data in the event of a catastrophic loss

As far as just moving the data the only solution we have for that is the backups NAS that can hold the mysql data temporarily but if the server is on it is also running a natural gas plant SCADA system and actively storing tag data to C and D. I can stop the SCADA service in server manager but not before it will start writing data. Customer is being super strict about not losing data points once they are created

[Electronics Wizardy]

Did you check the manual of the raid card?

 

But you should be able to do this.