To "hardware" RAID 5 or software RAID 5

Robin Laing Robin.Laing at drdc-rddc.gc.ca
Wed Dec 6 17:57:17 UTC 2006


On Mon, 2006-12-04 at 13:28 -0800, Gordon Messmer wrote:
> Robin Laing wrote:
> > On Sun, 2006-12-03 at 12:13 +0800, Hadders wrote:
> >> RAID 6 - less used, but like 5, but handles more than a single disk failure.
> > 
> > Thanks for this information.  I will have to look closer at RAID 6 for
> > my new file server.
> 
> Naturally, in order to provide the additional redunancy, you sacrifice 
> more disk space.  In a RAID5 set, the parity is stored on the equivalent 
> of the volume of one disk.  Your available space is N-1, where N is the 
> size of the smallest disk used.  In RAID6, the available space is N-2. 
> The additional redundancy is good if you have a large set of disks, but 
> if you've got just three, it's probably overkill.  RAID5 is the best 
> solution for a 3 disk set.
> 

I was looking at 5 disks minimum in the new server.  The better recovery
is what I am concerned with.  Just in case.  Backing up a TByte of data
is a pain.

How hard to move from RAID 5 to RAID 6 using software RAID?




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