On Tue, 25 Nov 2014 03:31:32 +0000 "Boylan, Ross" <Ross.Boylan@xxxxxxxx> wrote: > Thanks; I didn't know one could do that. > > But am I correct in my understanding that if 2 arrays have the same homehost 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. > > 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 *should* belong to, and the assemble the array with --update=homehost --homehost=real-host to "fix" the uuid. NeilBrown > > Ross > ________________________________________ > From: NeilBrown [neilb@xxxxxxx] > Sent: Monday, November 24, 2014 7:08 PM > To: Boylan, Ross > Cc: linux-raid@xxxxxxxxxxxxxxx > Subject: Re: homehost and 0.90 format > > On Tue, 11 Nov 2014 03:14:34 +0000 "Boylan, Ross" <Ross.Boylan@xxxxxxxx> > wrote: > > > 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 different 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 example, inhttp://marc.info/?l=linux-raid&m=123999237229707 Neil Brown says > > > 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 <system> > > > > The 2 UUIDS are > > 8691ad98:af955756:ae5efbfa:dfd20ce6 > > 6d89d3b5:19a0acce:319e1a9c:58606385 > > > > Thanks, > > Ross Boylan > > You need to guess-and-test. > e.g. > > mdadm --detail /dev/md7 --homehost=foo | grep UUID > > If it says "(local to host foo)", then "foo" is the correct name. > If not, then try a different name. > > NeilBrown > > > > > > 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@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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