From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: software raid and ERC Date: Wed, 18 Apr 2012 13:52:10 +1000 Message-ID: <20120418135210.24ff8db5@notabene.brown> References: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/nFukQ_tFB7sJfE37j+jcBvS"; protocol="application/pgp-signature" Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: "." Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/nFukQ_tFB7sJfE37j+jcBvS Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Wed, 18 Apr 2012 11:12:57 +0800 "." wrote: > Apart from the behaviour of the SCSI layer, does the linux software > raid layer have any concept of timeouts that would cause a drive to be > kicked when performing a deep recovery cycle? A storagereview forum > thread [3] claims that the linux software raid layer does not have a > concept of timeouts and does not care about ERC. In a web article [4] > the major NAS manufacturers that use software raid seem to agree with > this stance. Linux software RAID does not have a concept of timeouts. >=20 > On the other hand, how I interpret a previous post from Stefan [5] is > that the linux raid layer does have its own timeout mechanism that > will kick a non-responding drive. That aspect of that post is inaccurate. >=20 > > Without ERC-timeout, the drive tries to correct the error on > > its own (not reacting on any requests), mdraid assumes an error after a > > while and tries to rewrite the "missing" sector (assembled from the > > other disks). But the drive will still not react to the write request > > as it is still doing its internal recovery procedure. Now mdraid > > assumes the disk to be bad and kicks it. >=20 > Since I can't read code, I'm hoping that this list where software raid > development takes place would be able to clear up whether >=20 > a. Do delays caused by deep recovery cycles actually have any direct > impact on the linux software raid layer, or does it simply issue a > command to the underlying storage/scsi subsystem and block until there > is a response? md/raid in linux simply issues a command and waits for it to complete, eith= er with success or failure. NeilBrown --Sig_/nFukQ_tFB7sJfE37j+jcBvS Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBT446ajnsnt1WYoG5AQK2kw//clbeFGHlJso8xlS/fbWDNoktNVpGsHTu k2LdItG2GjjozBv0LDms5CKcMdpUz11LnKYuXo+Poeyqu21pM8HSRmc3lx2+PC2C M8prWV21jcz6Bud7jmOaCyzPdzxsGtIoBRDWyz5gzOEhHhByjb4T1GtewU1O8hmf sigHEh6TUjovHe19u3p8moXyiXTL9FsdBujWJtRv3mwYWRIncFogL5nVWxYVGbkB zQjBJV56mKr+e5GCScqXYVgOdr6dtjH+0wjxgeqksD2yWelhRhu2urOUW5Le80qQ 6jswHr6MbbacQ24EbQdRapOx2kvZ4xKnNqYqImhLK7ckpxuA0zo2HUScv+E7eFBr BjGJrg+tVF2TgndBrcJ6Fir3MaZrjJ2LI3lzisQYSy0P5ZtwoS101Tec8ZdFOTBw ekEdvtPEtyfBl9NYrBMLlAgaoYFQ3AT7rKiG72SucXwCqdbMdqUegkSGmK5KCLaM hc6rueUGiNf6O1qIBingpR9hgg1Hh65+lNA3pTGrB4jOa1/FDVZB9rNxAZLe7Knr vsizaZ3FnObPzjzmj5XFfL2UajvzvW2NPtROfPqMft+v94iGDGmffvGuFIBWFXl+ s5K+jlWFi4Qi77gIE6vktGmC4eJnb55qFgEQoFW483bh3M7UhIkKSxrCixtzTSxx 7KPt8efE+co= =JsSJ -----END PGP SIGNATURE----- --Sig_/nFukQ_tFB7sJfE37j+jcBvS--