Date: Wed, 09 Feb 2011 17:14:36 +0000 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: "$witch" <a.spinella@rfc1925.net> Cc: freebsd-questions@freebsd.org Subject: Re: ZFS over RAID6 Message-ID: <4D52CB7C.3040004@infracaninophile.co.uk> In-Reply-To: <4D52B0F6.9000006@rfc1925.net> References: <4D52B0F6.9000006@rfc1925.net>
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On 09/02/2011 15:21, $witch wrote:
> considerations :
>=20
> at lower level feel RAID6 meet my requirements (i love something that
> can face a double hw fault)
With ZFS that's called RAIDZ2 -- it's similar to RAID6 and it has the
same two-failure resilience characteristic.
> while at upper level ZFS looks very nice so am looking for such a
> combination.
>=20
>=20
> status :
>=20
> as now had found some ADPTEC, ARECA and 3WARE adapters that look
> reasonable but controller is not all;
> i need also 8 (+ 2 spare) HDs and a case where to keep them.
>=20
> so had extended research to 8HD cases with RAID6 capabilities.
Mixing ZFS and standard H/W Raid is not a good idea -- ZFS expects to
run on a collection of hard drives, not a composite disk array. Instead
of paying for a RAID controller, put the money towards extra RAM and/or
SSD cards to use for the ARC and the ZIL used by ZFS.
If you want ZFS but you're stuck with built-in RAID, then it's best to
configure the RAID as a JBOD and use ZFS over that.
Hot spares and ZFS is a current development topic on FreeBSD: automatic
replacement of a failed drive doesn't work properly. However, it should
be relatively easy for an admin to type commands to achieve the same effe=
ct.
Cheers,
Matthew
--=20
Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard
Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
JID: matthew@infracaninophile.co.uk Kent, CT11 9PW
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