Date: Sat, 17 Oct 2009 19:49:17 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Jeronimo Calvo <jeronimocalvop@googlemail.com> Cc: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: Data Redundancy RAID 0+1 Vs 1+0 FREEBSD 7.4 STABLE Message-ID: <4ADA11AD.3070101@infracaninophile.co.uk> In-Reply-To: <beaf3aa50910171129g45ef3751vd366d65b5c473394@mail.gmail.com> References: <beaf3aa50910171129g45ef3751vd366d65b5c473394@mail.gmail.com>
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Jeronimo Calvo wrote:
> Hi folks,
>=20
> 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...
>=20
> 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 workloa=
ds
seen on a general purpose workstation, it offers no advantages over RAID1=
0,
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) p=
lus
a good hardware RAID controller with plenty of battery backed cache RAM.
Cheers,
Matthew
--=20
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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