RAID 50 (NPG: 2) vs. RAID 6 (ADG) performance comparison ?

>I am reluctant to use RAID-5 because it is not recommended by HP for any LUN with 12+ drives.

Then why have you got two RAID 5s with 12 disks in each of them?

@andyalder: Because 12 is the maximum number of disks that is recommended by HP for RAID 5.

@Carlos Ijalba: Yes, that does make sense. So I will find some way to convert the RAID 50 with hot spare into RAID 6 (ADG).

So I guess, the general rule here is:

If the drive array has more than 12 disks, then use RAID 6 (ADG)
If the drive array has less than equal of 12 disks, then use RAID 5

correct me if I'm wrong ?
HP-Advanced-Data-Guarding-technology.pdf

@Malmensa: yes, this is Disk to Disk backup with Veeam software. The tape drive has been decommisoned last year since it is slower to restore using tape drive.

It actually says 14 in that document but it was written ages ago when drives were 36GB rather than 3TB, 12 is far too many for RAID 5 with modern drive capacities and in fact RAID5  it isn't recommended for anything any more. 25 disks and you should be looking at RAID 60 with 2 parity groups. You should also periodically check the ADU report for "read errors hard" as the disk manufacturers don't set predictive failure for bad blocks even though they'll stop RAID 5 from rebuilding properly.

Andy,

25x 500GB 2.5" SATA disks is for D2700 DAE, hence it is currently set as either RAID 6 (ADG) or RAID 50

My new D2600 only contains 12x 3 TB 3'5" SATA HDD, I have configured it as RAID 5 for capacity purpose.

Realistically, the recommendation in our days should be: Always use RAID-6.

But different manufacturers still use RAID-5, so use whatever suits you and what is recommended by your manufacturer's documentation & best practices, sometimes one size does not fit-all.

Andy,

Many thanks for the willingness to help here.

Here's my ADU report for the 3 controllers.
ADUReport.txt
ADUReport_1.txt
ADUReport_2.txt

Many thanks for the assistance.