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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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigDB3441485DA6BD533F7C668D Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable 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 --------------enigDB3441485DA6BD533F7C668D Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEAREIAAYFAkraEbYACgkQ8Mjk52CukIyZAwCdGcHvGUcnCfpzgIo7D81pxz/r 3+EAnjbeJkZOpHmYlkpHVoQko1P3K+fb =s5k9 -----END PGP SIGNATURE----- --------------enigDB3441485DA6BD533F7C668D--
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