Date: Fri, 29 Apr 2011 08:40:51 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: freebsd-questions@freebsd.org Subject: Re: Drive selection for gmirror Message-ID: <4DBA6B83.3040102@infracaninophile.co.uk> In-Reply-To: <4DB9E68B.2000908@wp.pl> References: <4DB9E68B.2000908@wp.pl>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigDAA7B12A4FD345E6187EF566 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 28/04/2011 23:13, Ireneusz Pluta wrote: > when selecting SATA drives for gmirror, boot device, connected to an > on-board controller, should I look for so-called "enterprise grade", or= > "raid edition" drives (like for instance > http://www.wdc.com/en/products/products.aspx?id=3D40), or I should rath= er > focus on models closer to "consumer grade"? Will gmirror configuration > significantly benefit from things like TLER, or it would rather be > harmful, like when using these disks as single ones in desktop > applications? gmirror doesn't do all of the really fancy stuff an expensive hardware RAID card will. So, if one disk in a mirror fails a write, the mirror breaks and has to be resynch'd. With gmirror that means manually entering a sequence of commands to remove and re-add the drive to the gmirror. "Enterprise" grade drives can be much more reliable over all as they are designed for 100% duty, whereas with consumer grade the expectation is that the drive will be turned off much of the time. This is typically one of the distinguishing features between SAS and SATA as well. "Green" drives can be particularly bad with FreeBSD, as they frequently end up spinning up and down continuously, which both wastes a lot of power and also shortens the life of the drive: neither of which adds to the actual (rather than claimed) green credentials of the device. Decide how much disk space you want, and what your budget is, then buy the best quality drives that match your criteria. I'd turn off TLER. 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 --------------enigDAA7B12A4FD345E6187EF566 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.16 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk26a4sACgkQ8Mjk52CukIyvywCdGzjPoTNOsq2pxRa8tv3Lk1ek K2EAnjHIb6nXjxl3PaiQDNOS1g+VScGR =eQcE -----END PGP SIGNATURE----- --------------enigDAA7B12A4FD345E6187EF566--
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