From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: bug: 4-disk md raid10 far2 can be assembled clean with only two disks, causing silent data corruption Date: Tue, 25 Sep 2012 22:32:27 +1000 Message-ID: <20120925223227.130ef8e3@notabene.brown> References: <50606207.7040804@gooseman.cz> <20120925141959.0c22de7d@notabene.brown> <152edbf7bdad33717477f174f94116b7@192.168.93.35> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/EL2spjba_hMJa+Kziv8k2gZ"; protocol="application/pgp-signature" Return-path: In-Reply-To: <152edbf7bdad33717477f174f94116b7@192.168.93.35> Sender: linux-raid-owner@vger.kernel.org To: jakub@gooseman.cz Cc: Mikael Abrahamsson , linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/EL2spjba_hMJa+Kziv8k2gZ Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Tue, 25 Sep 2012 11:48:34 +0200 wrote: >=20 > On Tue, 25 Sep 2012 07:00:44 +0200 (CEST), Mikael Abrahamsson > wrote: > > On Tue, 25 Sep 2012, NeilBrown wrote: > >=20 > >> Why do you say that "the write IO errors are invisible for the=20 > >> filesystem"? They are certainly reported in the kernel logs that you=20 > >> should and I'm sure an application would see them if it checked return= =20 > >> status properly. > >> > >> md is behaving as designed here. It deliberately does not fail the=20 > >> whole array, it just fails those blocks which are no longer accessible. > >=20 >=20 > Would you please refer to some documentation that this behaviour is > correct? I now tried to fail several disks in raid5, raid0 and raid10-nea= r, > in case of r0 and r10n, mdadm didn't even allow me to remove more disks > than is sufficient to access all the data. In case of r5 I was able to fa= il > 2 out of 3, but the array was correctly marked as FAILED and couldn't be > accessed at all. I'd expect that behaviour even in my case of raid10-far.= I > can't even assmenble and run it with less than required count of disks. >=20 Could you please be explicit about exactly how the behaviour that you think of as "correct" would differ from the current behaviour? Because I cannot really see what point you are making - I need a little help. Thanks, NeilBrown --Sig_/EL2spjba_hMJa+Kziv8k2gZ Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBUGGkWznsnt1WYoG5AQIIbRAAlG+/mbs2QvvyBApoOcYESQ6IFjMpnUnK 7JDfKAwpw3vyiQEAORwAe6+7f0zu0ivzMa/ufCuktkw0L5W2zCzF3sfcK+d7CHDe g6hGwXPjnSOgZQQyJM07auEC5sDp4QYpb0zwEzSx433TI4jRe7/zzKWGxjI4b6hv k6RnUMwHI1NNFqa3pH1BlCmquuDlwLQ/zCd9gWOA4Tamg0qnK+wF5utci66+37Xl B1AgoUg6yClQpOV8F3IHdREvx1CpZb4zP3TtJZV2s0QThX2KYcJNliV0+wKR1J5U 3p1CTJC33QyJiOamM7J6HNXTZpz7VeATNhcp2sSl720Y4B9hMLHu7BQhSA0LMAkM IZIPq9/W+ugCA02itBLaoEPhBUsrUzrZFsI77nBUrkvFPsF1E5vUCm2QayDBZDE+ 2S0YSyFHSHUSs0ZgFALWe8QybNY99mZdMKmsKUac1jdPTWHWnn/SjHVh0giinV4T BsZh+VGxskL5HhmvrlndUx7OZjq0qclRoyPQu+ge8NZp6fLKbqC0z70OR4OlZv9D zZ1TSRvxlwLTZYfgcVkU9noT5mcKrdObfhwNgb3tUlg48WLCfdDMVes5EvrVfpAD XsS1FPdaLkvAkgu274wkkupTlVHMSCn4G0UOCarjwcHQRt0I2tJP9WV8ey5kHbNa QdpDt8fqdlQ= =hZ+T -----END PGP SIGNATURE----- --Sig_/EL2spjba_hMJa+Kziv8k2gZ--