Growing RAID5 without back up data?

[sumasage]

I am trying to build a media server for my home and still in the process of evaluating my OS options (Ubuntu Server, Fedora Core, or Win Server). I am planning to use four 1TB drives initially for the RAID5 array. Once it fill up i will add more 1TB drives.

My question is can Fedora Core create a RAID5 array and grow latter without having to back up data to external hard drive and re-create the array? I am looking for something that is easy to use and manage. If Fedora Core doesnt have this option, can you recommend other distributions that can do this?

Thanks.

[Irithori]

Any recent distribution (from kernel 2.6.17 onwards) can do this via *softraid*.

mdadm --add /dev/<MD_DEVICE> /dev/<NEW_DISK>
mdadm --grow /dev/<MD_DEVICE> --raid-devices=<NUMBER +1>

Whether or not you can expand a hardware raid depends on the capabilities (and price) of the raid controller.


In any case:
This is a massive one-way operation.
A backup before raid growing is highly recommended.

Think:
- Human error ("Oops, wrong device")
- Power Outage during the operation
- Some (hardware) limit might be hit: some older controllers cannot address partitions >2TByte
- etc