From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: Simultaneous assembly on multiple hosts Date: Mon, 6 May 2013 16:32:03 +1000 Message-ID: <20130506163203.7a65786b@notabene.brown> References: <20130504020146.GD31411@chc-5.metaname.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/uaF.Hn+A7j.G6s+tKNQTsjp"; protocol="application/pgp-signature" Return-path: In-Reply-To: <20130504020146.GD31411@chc-5.metaname.net> Sender: linux-raid-owner@vger.kernel.org To: Neil Matai Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/uaF.Hn+A7j.G6s+tKNQTsjp Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Sat, 4 May 2013 14:01:46 +1200 Neil Matai wrote: > Hi all, >=20 > Is it dangerous have an array assembled on two hosts at the same time? > Say I have servers A and B exporting devices a and b via ATA over > Ethernet or similar to hosts C and D. If a and b are components of an > array then both C and D automatically assemble the array as soon as > the components a and b are exported but is this safe (on the proviso > that only one of C or D is ever writing to the array at any time and > that there is no write-behind caching above the array device)? >=20 Yes, it is dangerous. Both hosts will try to update the metadata and will trip over each other. NeilBrown --Sig_/uaF.Hn+A7j.G6s+tKNQTsjp Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIVAwUBUYdOYznsnt1WYoG5AQJ/rA/9E/H1dawxxttVLp3cRdWm7hhEH+HpzL9G oYsY5jim7navAz+DafDf4OVIFjFml2/44ZVwsh7/4QqEpYQCeubNHpOlG3WA6uGl 76cfaRQKTh1LpkeWwJZwzOAiV9NriEw7ow8LQnpfPP7NHj7/T4gMDIFKkfWQGe/E ZVymKrzziFJUU+AjpkM+JQ4jMiONSKhSTO7GQToAacjcEChTeKMp4837D98SFUL4 /97rhZrgzzUeWbXIWfh2Cdzqepe7e9n3C3BtfxQ639cl14ZIADzspxbD5WKImEu1 O056X/SXmE2cn/E3ws5RTAZ7Yy7SCb0irNw2ygILgJfzhj2LlDIHyRABsJX+yiMd rGVFv815VBNb3GyzwNFzZVtOXDuhbTs9xPteU3Pjxe+JjSFjse/vyz38DzR2ly3r RYZknhmaaGLetxHtcy2709rf2zgcqCmLPkFYlEMsdujxsA4B1p03C1sNcDK8KyCv ZdgzYlUe5mfGmjs1cBHOtNrS604MBHOEvmLQIdBmDXIl4tJOX4R5gL4h1sEYMB8q L74ScDVBaZdekVF4bqhJVUPHuBgNmWf8+d/I315daGaBXm7Wg+65VTYM45JOunuC BhhDzbLZXNUBI4WpfL2QkNmKHrQbwgpQvo7+6fm7qTdI/8wwrMVJ5TWoW1Is7s0J 4Z7sMN/SNP0= =J8A1 -----END PGP SIGNATURE----- --Sig_/uaF.Hn+A7j.G6s+tKNQTsjp--