Data Redundancy RAID 0+1 Vs 1+0 FREEBSD 7.4 STABLE

[Matthew Seaman]

Jeronimo Calvo wrote:
> Hi folks,
> 
> I'm thinking to build a Raid on my system and I'm getting documented
> abut 0+1 and 1+0 RAID systems.
> As far as I can see the best option is a 1+0 is the best option as if
> one of the from mirrors fails, the RAID still be redundant and in the
> case of a 0+1 RAID, If one of them fails, the RAID will be down until
> u replace the HD in question...
> 
> So my question is, if I am right above, what are de benefits of
> mounting a RAID 0+1 ??

For workloads that involve streaming large volumes of sequential data
RAID 0+1 can perform very well.  However, for the typical sort of workloads
seen on a general purpose workstation, it offers no advantages over RAID10,
and for the sort of workload you get with RDBMSes -- lots of randomly
scattered small IOs -- RAID10 does the business.

Given the poor resilience characteristics of RAID 0+1 the sequential
data streaming workload would be better handled by RAID5(0) or RAID6(0) plus
a good hardware RAID controller with plenty of battery backed cache RAM.

	Cheers,

	Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.                   7 Priory Courtyard
                                                  Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey     Ramsgate
                                                  Kent, CT11 9PW

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