From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: Running check and e2fsck simultaneously Date: Mon, 11 Nov 2013 09:51:24 +1100 Message-ID: <20131111095124.560dc6c0@notabene.brown> References: <527FCBAF.4070208@hardwarefreak.com> <58CD4AD8-0A1E-42E8-984D-F4727EE2B8F0@gmail.com> <527FDBC1.4000009@hardwarefreak.com> <20131111073428.583b83b2@notabene.brown> <52800A73.9020401@hardwarefreak.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/zGvgnexs5qVh=Os=0Ngi4Su"; protocol="application/pgp-signature" Return-path: In-Reply-To: <52800A73.9020401@hardwarefreak.com> Sender: linux-raid-owner@vger.kernel.org To: stan@hardwarefreak.com Cc: Ivan Lezhnjov IV , "linux-raid@vger.kernel.org" List-Id: linux-raid.ids --Sig_/zGvgnexs5qVh=Os=0Ngi4Su Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Sun, 10 Nov 2013 16:36:35 -0600 Stan Hoeppner wrote: > On 11/10/2013 2:34 PM, NeilBrown wrote: > > On Sun, 10 Nov 2013 13:17:21 -0600 Stan Hoeppner > > wrote: > >=20 > >> Also, I see little/no value in running a scheduled mdadm check on a > >> RAID1 array. Any problems with RAID1 will be due to one of the disks > >> beginning to fail in some mode, usually requiring sector relocation. > >=20 > > I think scrubbing has value on any RAID with redundancy. >=20 > That's a bit... redundant, Neil. :) RAID0. Sadly a name that is used, even though it is an oxymoron. >=20 > > The firmware can only relocate a sector if it reads it when it is margi= nal > > but not yet completely lost. If a sector is not read for a long time a= nd > > during that time the media degraded beyond recovery the firmware cannot= do > > anything. But RAID1 can - it can get it from the other device. >=20 > But is a scrub required for this? Isn't this exactly what occurs during > normal operation with md/RAID1? I.e. a read fails with disk error, so > we grab the sector from the mirror? So what advantage is there to > scrubbing md/RAID1? >=20 If scrubbing finds and repairs a (rarely accessed) bad sector on one drive before the other drive dies completely, that is a win. NeilBrown --Sig_/zGvgnexs5qVh=Os=0Ngi4Su Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIVAwUBUoAN7Dnsnt1WYoG5AQJ9nRAAnQkJICQmaQCgojeoWxU47KW7g/RYdmO4 Ar52BRo6Exb6a1nJmkBNy99fG8Aw7CiYBsAnmuCwdKjRg3YZX0FnKeQmiJwvOXES BSnqU9yGAy4gHjzzYat0fjUhiXk2zlN6viroE8j8yAh9lEDqiCbdGKHk0TXBS4GX 6Mi2RDWZMJT7PY9X+1gWdz9PNTYe7yYtc1MYzkzhV2AsLYvEMe4XObcEQjxoUUjE dq/hb19JNzol0+Ttt2rF6NKzrYtH/AsrsCMb8f5HJfk7JIkV4McHZMibajSFuirE U1Cl8F2k0EicoWCxO8NeBpsW/8kN7drhb+quFKi/xZ9r/d7cIX6uDZWYl1dBg+zn p8GggsDZ5sLlfmg1wOTbubWxNRn4jP6Ntt5CBXWI04f5w1+xfgMnXSFQHMcALIQR OupN+eFvl5c/Fi5orzlpXbwR6wSKfW4ogR+od7f+Lha4HfRGLYVOuheGiSP5z7zo L+Fz4ozzHEv/8mYP8Ns74P2vz8LPc7jEaIw+mtBRJJe82P9nbfttpw9DtMHx/Ane JP6f50SuDuSjhnEQAZ8Zl4/yYwOmHBiPXsQKQTVHt8T/SuEz6rYgQZFQufTsBT+w xqEwKF05AHdrxN80dp1JIBTM7ZwR7Dy4jurJ4ZXn17pZ/JZwDliwvn3UODSm9OoS MEpC6HqrAGI= =Bq2J -----END PGP SIGNATURE----- --Sig_/zGvgnexs5qVh=Os=0Ngi4Su--