* homehost and 0.90 format
@ 2014-11-11 3:14 Boylan, Ross
2014-11-25 3:08 ` NeilBrown
0 siblings, 1 reply; 4+ messages in thread
From: Boylan, Ross @ 2014-11-11 3:14 UTC (permalink / raw)
To: linux-raid@vger.kernel.org
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
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
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: homehost and 0.90 format
2014-11-11 3:14 homehost and 0.90 format Boylan, Ross
@ 2014-11-25 3:08 ` NeilBrown
2014-11-25 3:31 ` Boylan, Ross
0 siblings, 1 reply; 4+ messages in thread
From: NeilBrown @ 2014-11-25 3:08 UTC (permalink / raw)
To: Boylan, Ross; +Cc: linux-raid@vger.kernel.org
[-- Attachment #1: Type: text/plain, Size: 3027 bytes --]
On Tue, 11 Nov 2014 03:14:34 +0000 "Boylan, Ross" <Ross.Boylan@ucsf.edu>
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@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
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^ permalink raw reply [flat|nested] 4+ messages in thread
* RE: homehost and 0.90 format
2014-11-25 3:08 ` NeilBrown
@ 2014-11-25 3:31 ` Boylan, Ross
2014-11-25 4:02 ` NeilBrown
0 siblings, 1 reply; 4+ messages in thread
From: Boylan, Ross @ 2014-11-25 3:31 UTC (permalink / raw)
To: NeilBrown; +Cc: linux-raid@vger.kernel.org
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.
I am able to guess the homehost for one of them using your trick; none of the possibilities have tried have matched the other.
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
On Tue, 11 Nov 2014 03:14:34 +0000 "Boylan, Ross" <Ross.Boylan@ucsf.edu>
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@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: homehost and 0.90 format
2014-11-25 3:31 ` Boylan, Ross
@ 2014-11-25 4:02 ` NeilBrown
0 siblings, 0 replies; 4+ messages in thread
From: NeilBrown @ 2014-11-25 4:02 UTC (permalink / raw)
To: Boylan, Ross; +Cc: linux-raid@vger.kernel.org
[-- Attachment #1: Type: text/plain, Size: 4169 bytes --]
On Tue, 25 Nov 2014 03:31:32 +0000 "Boylan, Ross" <Ross.Boylan@ucsf.edu>
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@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
>
> On Tue, 11 Nov 2014 03:14:34 +0000 "Boylan, Ross" <Ross.Boylan@ucsf.edu>
> 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@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
>
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