From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Hill Subject: Re: RAID 5 build time optimization question and experiments. Date: Fri, 11 Dec 2009 15:29:38 +0000 Message-ID: <20091211152938.GA5857@cthulhu.home.robinhill.me.uk> References: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="SLDf9lqlvOQaIe6s" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids --SLDf9lqlvOQaIe6s Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri Dec 11, 2009 at 02:55:31PM +0000, Cat'Killer wrote: > I found a way using Doug Gilbert's great sg3utils to zero all these > disks in a very efficient manner, using sgp_dd, at near drive > bandwidth, and proceeded to zero all the disks fully in about 4 hours! >=20 > Once done, I then created a RAID 5 on 10 disks, waited for the rebuild > to complete, stopped the array using mdadm, and dumped each of the > RAID's components superblocks to files. >=20 <-snip-> > The create worked fine and I waited for the rebuild to be complete > before stopping the array and dumping the SBs. >=20 > I then proceeded to write these same superblocks to 10 new similar > disks in a different system. > You could just do the create with --assume-clean, which should take very little time at all. If the drives were zeroed initially then this will give you valid parity data. Cheers, Robin --=20 ___ =20 ( ' } | Robin Hill | / / ) | Little Jim says .... | // !! | "He fallen in de water !!" | --SLDf9lqlvOQaIe6s Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.11 (GNU/Linux) iEYEARECAAYFAksiZWEACgkQShxCyD40xBJygQCfVmvQxuJX0oD21LnJLjO3VKze xC4AnibaRJPNz/1nuUmYl08V7LrhjWPi =KzQ4 -----END PGP SIGNATURE----- --SLDf9lqlvOQaIe6s--