Proliant DL380-G4 with the onboard SmartArray 6i controller.
Raid 1+0 set consisting of 2x 72 G and 2x 300 G disks (the bigger disks got added later).
Effective capacity about 140 GB and, of course, it is full.
I can't add more disks because the remaining 2 slots are taken by another 2-disk mirror. I can replace the 72 G disks (1 at a time) by 300 G disks and (after rebuilds) grow the array. No redundancy during the disk-swap though. And that 2x :-(
Or I change the array from Raid 1+0 to Raid 5 which will just give me 70 G extra (which is sufficient), but keeps (hopefully) the redundancy intact during the change.
Backup, kill the array, replace the small disks, create new array, then restore is not an option as I need to keep this box online at all times.
I'm not worried about the performance-loss during a rebuild. (User-access to the data is luckily enough quite light in this case.)
I'm looking for recommendations how to get the disk-space quickly upgraded, if possible while maintaining redundancy.
Edit: Changed server-type into G4 (I've got both in the server-room and got them mixed up.)
The HP ProLiant DL380 G5 has a Smart Array P400i RAID controller and 8 drive slots. The HP ProLiant DL380 G4 has a Smart Array 6i controller and 6 drive slots. I'm trying to understand your arrangement... The process for expansion will be the same, though...
That makes the easiest path to expansion of the array a simple drive replacement. You will need two 300GB disks. Replace one of the 72GB drives with a 300GB disk and allow the array to rebuild. When that is done, replace the other 72GB disk with a 300GB drive. That will result in a ~600GB usable RAID 1+0 array. I would not be worried about redundancy during the process of the drive expansion. You're only copying 72GB per disk and the rebuild time will be short.
This is covered in detail here: What are the good ways to migrate a RAID array to bigger disks?
Do you have any HP management utilities installed? What is the operating system type and version? Do you have a charged Battery-Backed Write Cache (BBWC) on the controller? That will be needed if you want to do an array transformation or expansion online.
You can convert the RAID 1+0 array into a RAID 5, but since you already have 300GB disks, you should probably complete the job with bigger drives. Plus, why cripple your performance by dropping to RAID 5?
Can you also clarify which server you have?
DL380 G4
DL380 G5