From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: mdadm --monitor: need extra feature? Date: Wed, 22 Aug 2012 17:44:35 +1000 Message-ID: <20120822174435.685d80d4@notabene.brown> References: <503365EB.6000006@supersystem.pl> <503366A1.9030307@hesbynett.no> <50337654.9000905@supersystem.pl> <50338185.4020003@websitemanagers.com.au> <503486C7.70503@supersystem.pl> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_//=FDrHgeXHoEsKwGAxiLIlI"; protocol="application/pgp-signature" Return-path: In-Reply-To: <503486C7.70503@supersystem.pl> Sender: linux-raid-owner@vger.kernel.org To: Sergiusz =?UTF-8?Q?Brzezi=C5=84ski?= Cc: Adam Goryachev , linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_//=FDrHgeXHoEsKwGAxiLIlI Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Wed, 22 Aug 2012 09:14:15 +0200 Sergiusz Brzezi=C5=84ski wrote: > W dniu 21.08.2012 14:39, Adam Goryachev pisze: > > On 21/08/12 21:51, Sergiusz Brzezi=C5=84ski wrote: > >> > >> > >> W dniu 21.08.2012 12:44, David Brown pisze: > >>> On 21/08/2012 12:41, Sergiusz Brzezi=C5=84ski wrote: > >>>> Hi, > >>>> > >>>> I use Raid1 to make backup of the whole system. > >>> > >>> Raid is not a backup system. It is to improve uptimes, minimise > >>> downtimes due to > >>> disk failures, and possibly to improve disk speed and/or capacity. > >>> > >>> I would recommend you first think about what you are trying to > >>> achieve here - > >>> what are you trying to back up, how do you see restores being used, h= ow > >>> efficiently are you using your hardware, your bandwidth, your time > >>> and effort? > >>> > >>> You would probably be better off with a normal fixed 2-disk raid1 to > >>> minimise > >>> the problems caused by a single disk failure, combined with an rsync > >>> snapshot > >>> style backup that can be fully automated and give quick and easy > >>> recovery of > >>> multiple old versions of files in the face of the most common cause > >>> of data loss > >>> - human error. > >> [...] > >> > >> I know, I know. Raid is not a backup system :) > > Aside from RAID is not a backup, perhaps the more useful suggestion > > would be to use the right tool for the job... > > > > So, again, ignoring that you possibly should not be using RAID for a > > backup... how about using udev scripts to see when you plugin a drive, > > and that script can check the UUID against any md arrays, and if it > > matches, add it to the array.... >=20 > I wrote a script making this work. It runs once a hour. I pass the parame= ter=20 > with md device to the script. It checks the state of the array with "mdad= m=20 > --detail". If there is something wrong (State : degraded) it reads UUID o= f that=20 > array. Then it scans for /dev/sd* partitions and checks with "mdadm --exa= mine"=20 > if UUID matches. If so, the partition can be added with "mdadm --add". Th= at is=20 > why I asked abut this feature in mdadm - recognising if there is a new pa= rtition=20 > belonging to monitored array. With mdadm this procedure would work on ele= gant=20 > manner. > udev really is the right way to do this. Just get udev to run mdadm -I /dev/newdev whenever a device is discovered. It can then be automatically re-added depending on the policy set up in mdadm.conf. "mdadm --monitor" will not gain this functionality. It is for monitoring active arrays, not for monitor new devices. NeilBrown --Sig_//=FDrHgeXHoEsKwGAxiLIlI Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBUDSN4znsnt1WYoG5AQIGGA/6AxaD2IA/HcshS3bg5qgcnmjRIqSowYvO oW5NTq1ejC8/hwORrxdw9pkguuUUeymAcQYXqU/GAmhd6UHq4D2THLSj1kz+esWb eWuxb9tOOEZ4XnV0xNtMxIo8v4HgA3IAV0oFWEdjLHWhbnYZewIl/qPqx7sTyzYz uUkqqjspkKUterDXJVJdzGdye70+7GK3qWrqInw4xrBpNSOEB9dTTyEPK8NrcNpa EVl6BrwBvCTZXjMmltRCDPtcuD39U254sSNhnXiHjwo5F+wW4dBjpX3TNeowRu6L KFxOHaqZfxUy/FjXA/SLiDI1wJXmHZfV3TePtzupVfLwx31vzAWcyig9vpelFYEJ H6sRhSfkiwrgBmnV4dK+gu05OrTK0kcKQnjtTVL+ReAkPq4TBHRneazpj0Xh6Y2C G8Ok1BR2SB9VLJK1q/V1zp0C3WS4jFkdYaNLcSTZQQE0GsDnRGQzBNe8gPwgwS+D Ss3t/ZQIbc4AGFxmm0RJkIiZB/GMujr3nd9unC6A9MQWIIHfsE4WlvHMk1I+Lkaz 4adf/S7cpy1cI7jlFAe5QUr5CskbLuFuaIjv06vWpI2VBY/IHnpaKYHaAuL6wd51 FvGqXhWAZHQMoYKGlZOMKGGtIAQ3DQjMBijgmDUPj8ry9eWwDy92wVDXZDqDfZPt H64Arjy7Pjs= =dFr4 -----END PGP SIGNATURE----- --Sig_//=FDrHgeXHoEsKwGAxiLIlI--