On Tue, 2009-06-02 at 16:36 +1000, Adam Goryachev wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> > With a modern filesystem capable of multiple copies of each file this
> > can be overcome. ZFS can handle multiple drive failures by selecting the
> > number of redundant copies of each file to store on different physical
> > volumes.  Simply put, a ZFS RAIDZ with 4 drives can be set to have 3
> > copies which would allow 2 drives to fail.  This is somewhat better than
> > RAID1 and RAID5  both because more storage is available yet still allows
> > up to 2 drives to fail before leaving a rebuild hole where the storage
> > is vulnerable to a single drive failure during a rebuild or resilver.
> 
> So, using 4 x 100G drives provides 133G usable storage... we can lose
> any two drives without any data loss. However, from my calculations
> (which might be wrong), RAID6 would be more efficient. On a 4 drive 100G
> system you get 200G available storage, and can lose any two drives
> without data loss.

So isn't this the same as RAID10 w/ 4 drives, 200GB and can lose 2
drives (as long as they aren't on the same mirror) and no risk of
corrupted parity blocks?


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