From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: homehost and 0.90 format Date: Tue, 25 Nov 2014 15:02:37 +1100 Message-ID: <20141125150237.17f2ddfc@notabene.brown> References: <20141125140821.6ece0afb@notabene.brown> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/NpgYCDt6oTIHq113LKkbX3/"; protocol="application/pgp-signature" Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: "Boylan, Ross" Cc: "linux-raid@vger.kernel.org" List-Id: linux-raid.ids --Sig_/NpgYCDt6oTIHq113LKkbX3/ Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Tue, 25 Nov 2014 03:31:32 +0000 "Boylan, Ross" wrote: > Thanks; I didn't know one could do that. >=20 > But am I correct in my understanding that if 2 arrays have the same homeh= ost they will have the same end (last half?) of the UUID? That would mean = the 2 devices I'm looking at can't have the same homehost. Yes, that is correct. >=20 > I am able to guess the homehost for one of them using your trick; none of= the possibilities have tried have matched the other. Can't help you there, sorry. You can always look at the content of the array, device what host it *shoul= d* belong to, and the assemble the array with=20 --update=3Dhomehost --homehost=3Dreal-host to "fix" the uuid. NeilBrown >=20 > Ross > ________________________________________ > From: NeilBrown [neilb@suse.de] > Sent: Monday, November 24, 2014 7:08 PM > To: Boylan, Ross > Cc: linux-raid@vger.kernel.org > Subject: Re: homehost and 0.90 format >=20 > On Tue, 11 Nov 2014 03:14:34 +0000 "Boylan, Ross" > wrote: >=20 > > I am trying to figure out which of my RAID devices is considered home. = I haven't switched machines, but I have several operating systems, with di= fferent hostnames, on the machine. 0.90 format metadata. > > > > Even 2 RAID devices created on the same OS don't seem to have any UUID = in common. i thought that the end of the UUID's would be the same. For ex= ample, inhttp://marc.info/?l=3Dlinux-raid&m=3D123999237229707 Neil Brown sa= ys > > > Note that 0.90 metadata does contain homehost information to some > > > extent. When homehost is set, the last few bytes of the uuid is set > > > from a hash of the homehost name. That makes it possible to test if a > > > 0.90 array was created for 'this' host, but not to find out what host > > > it was created for. > > > > mdadm.conf has > > HOMEHOST > > > > The 2 UUIDS are > > 8691ad98:af955756:ae5efbfa:dfd20ce6 > > 6d89d3b5:19a0acce:319e1a9c:58606385 > > > > Thanks, > > Ross Boylan >=20 > You need to guess-and-test. > e.g. >=20 > mdadm --detail /dev/md7 --homehost=3Dfoo | grep UUID >=20 > If it says "(local to host foo)", then "foo" is the correct name. > If not, then try a different name. >=20 > NeilBrown >=20 >=20 > > > > Details: > > > > root@wheezy4:~# mdadm --detail /dev/md7 > > /dev/md7: > > Version : 0.90 > > Creation Time : Fri Oct 3 17:20:13 2014 > > Raid Level : raid1 > > Array Size : 48828352 (46.57 GiB 50.00 GB) > > Used Dev Size : 48828352 (46.57 GiB 50.00 GB) > > Raid Devices : 1 > > Total Devices : 1 > > Preferred Minor : 7 > > Persistence : Superblock is persistent > > > > Update Time : Tue Nov 4 17:48:40 2014 > > State : clean > > Active Devices : 1 > > Working Devices : 1 > > Failed Devices : 0 > > Spare Devices : 0 > > > > UUID : 8691ad98:af955756:ae5efbfa:dfd20ce6 > > Events : 0.1 > > > > Number Major Minor RaidDevice State > > 0 8 20 0 active sync /dev/sdb4 > > root@wheezy4:~# mdadm --detail /dev/md8 > > /dev/md8: > > Version : 0.90 > > Creation Time : Tue Sep 30 13:27:56 2014 > > Raid Level : raid1 > > Array Size : 970702784 (925.73 GiB 994.00 GB) > > Used Dev Size : 970702784 (925.73 GiB 994.00 GB) > > Raid Devices : 2 > > Total Devices : 1 > > Preferred Minor : 8 > > Persistence : Superblock is persistent > > > > Update Time : Mon Nov 10 18:16:11 2014 > > State : clean, degraded > > Active Devices : 1 > > Working Devices : 1 > > Failed Devices : 0 > > Spare Devices : 0 > > > > UUID : 6d89d3b5:19a0acce:319e1a9c:58606385 > > Events : 0.790792 > > > > Number Major Minor RaidDevice State > > 0 8 19 0 active sync /dev/sdb3 > > 1 0 0 1 removed > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html >=20 --Sig_/NpgYCDt6oTIHq113LKkbX3/ Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIVAwUBVHP/XTnsnt1WYoG5AQKPLQ/8CFv7Y6YKUa5FsCWyLEyC/XGj7QUUyigo 7Cn8jvGKeeYa1gWnVwtlRUWlR/9BiojgUDy0TZTAycY80iHHu8rprIEOOb7eSdi6 IAAp5BItV6vmSSRfNDE5icahUMBdUBM0SkfBl7U2XRjd7MAUvI3mIrEZFPWJkkSJ Vp40D0O3XVi63LVEJa9VI/75iD5crOYbl0vvtWZ7iZqeOZQkcMTYmdwb2qL5p0It Al0k/kSHV9c8Q5P+mI37FBJM2pQG1RrcUCb/MRAQVxcP/cNKvrg34nQZ4IR0Hwpn EDwtVPmYkuSDopX/5qdJfiT8xRaoxR+NCOL5yIKI8WWAfqdibDHl/nNEwuHIBaTv 4WnQrDc1x2BtYjetisR4v8RXc+0gc7/6o3RpmN1Pkv7XJ5iqgXSrysFVsUbukvMj wdGjb8llYejnp3ObZF3PNxCNidNOHHwCgnXzFeqvHaEDjEnQ03flECxi4UzdyhNK KvAEAX9qMP+0G43dw9gsEmetm9XySW+HBZd5GkyWBPOSDgwLHjavV5462X0gcoL5 envGcYiSwWaGGF6T8gdWzowQ1IkYB151F1FCPC5MedIv3veEXFUj6TetUqULVHyw yw4PI5mqINe8gz4b9SWkEP3AGFRM1Bsz7hPUgshoMc0yg35rvJmWZfHVBrR9bGWV hsFtVIUDoSw= =dcuu -----END PGP SIGNATURE----- --Sig_/NpgYCDt6oTIHq113LKkbX3/--