[CentOS] OT: What's wrong with RAID5

[Les Mikesell]

Fajar Priyanto wrote:
> Hi all,
> Sorry for the OT.
> I've got an IBM N3300-A10 NAS. It runs Data Ontap 7.2.5.1.
> The problem is, from the docs it says that it only supports either
> RAID-DP or RAID4.
> What I want to achieve is Max Storage Capacity, so I change it from
> RAID-DP to RAID4, but with RAID4, the maximum disk in a RAID Group
> decrease from 14 to 7. In the end, either using RAID-DP or RAID4, the
> capacity is the same.
> 
> Now, why RAID5 is not supported? I believe using RAID5, I can get more
> storage capacity, can't I?
> I also notice with some onboard RAID controller, they only support
> either RAID0, RAID1, or RAID1+0. No RAID5.
> 
> What's wrong with RAID5, is there any technical limitation with RAID5?


I think that's a re-branded Netapp FAS 2020.  NetApps let you grow volumes by 
simply adding disks and with raid4 if you initialize the new disk to all zero's 
you don't have to recompute/rebuild the parity which is on a separate disk. 
That doesn't work with raid5. It's probably the wrong device if your first 
concern is being cheap.

-- 
   Les Mikesell
    lesmikesell at gmail.com