From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: Creating a 3-disk RAID6 array Date: Thu, 17 May 2012 11:38:17 +1000 Message-ID: <20120517113817.7faf9c1e@notabene.brown> References: <4FB4534A.5070608@volatilevoid.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/8dUHOPmtQGW1sNcKIWU+nXP"; protocol="application/pgp-signature" Return-path: In-Reply-To: <4FB4534A.5070608@volatilevoid.net> Sender: linux-raid-owner@vger.kernel.org To: Oliver Martin Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/8dUHOPmtQGW1sNcKIWU+nXP Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Thu, 17 May 2012 03:24:26 +0200 Oliver Martin wrote: > Hi, >=20 > is there any specific reason why md refuses to create a RAID6 array with= =20 > 3 disks? My (probably naive) understanding suggests it should be the=20 > same as a 3-disk RAID1, similar to a 2-disk RAID5. I'll have to leave for for hpa to answer. I've occasionally thought that maybe it should be fixed, but it never seemed worth the effort. >=20 > The reason I'm asking is that I currently have space on three disks for=20 > a new array, and would like to expand it when I add a fourth. I tried=20 > this scenario with a few loopback devices, but the only way to go from a= =20 > 3-disk RAID1 to a 4-disk RAID6 seems to be via an intermediate 3-disk=20 > RAID5, requiring two reshapes. I'd like to avoid one of them, if at all=20 > possible. Yes, not possible at present. It might be as simple and finding the places that impose the limit and dele= te them... NeilBrown >=20 > Regards, > Oliver > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html --Sig_/8dUHOPmtQGW1sNcKIWU+nXP Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBT7RWiTnsnt1WYoG5AQKTQxAAmMfkpRgmybqiL0HVx42huQ7c2hfhYUs4 hZTOofr4kJRVqqiSo3HuSGNvcJc3xJWxY7pwTepAdPTjJbRvuAzNbMUdZrld9D0n VfTgUrcTSHmUgRUaMqLGYI+arkXH9TZYKQ0f1mvEkNFYJ+7UQiBArCemUDdS/Y3x YMlodiUuPifJ22gOKASMOPkOFofT4BBmYquJTWOXvNBP66t8C8EOJ9jxiGlb/2gY 5ZtRRX7NdES10BquCoei6t7A0wpWcpy6QyIDtnMV+EAhfE1v9iW2Bov7YsMRWlY8 CdnFIKW+uNBsKZtaFHlE8v4TowUsnqSxGPMjYKS74sH0Gu76eF2QlEIhoEvvzRlg RV4sWpGi/JsqWqcZnvdpR6+dFR2ZvBFLWT028Hsnv/ZRW+IJy+xMsly8X1eeh7vu VpqU9qDqxAXq2CfSq1NcmZoOrC2Rs3l5ujz1HQxEzybPD+hIcDj7UsJsNiQpcO2X LgDr5VgDctp4fTPXX1Rg1ZvDLJds1JLHBGroAKWNff4LbU12tUf3yWnUtISmYnwV WLQU7d2e/r62jrTwh8apzFqC2PcUEnGSME+d7Cz568h8IhIlB1V0E0I3Bu4RbcsD RPgP3kLI2MleB+eZqhgWh9lMNHbvIq1h2BynQSDF9Go1oRPd66MiTEYq9e49sWXR ljBHGpTS6UA= =y0Wj -----END PGP SIGNATURE----- --Sig_/8dUHOPmtQGW1sNcKIWU+nXP--