Mailing List Archive: DRBD: Users

Lower device already claimed error

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lin at groupon

Jul 10, 2012, 3:54 PM

Post #1 of 13 (1069 views)
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Lower device already claimed error

Hi I'm setting up drbd on a Linux 2.6.18-238.el5. When I'm doing drbdadmin attach, i get error:

/dev/drbd1: Failure: (114) Lower device is already claimed. This usually means it is mounted.
Command 'drbdsetup /dev/drbd1 disk /dev/sda2 /dev/sda2 internal --set-defaults --create-device' terminated with exit code 10

sda2 should by no means be mounted:
[root [at] mbus ~]# mount -l
/dev/md1 on / type ext3 (rw,noatime)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
/dev/md0 on /boot type ext3 (rw)
tmpfs on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)

Any pointer how to resolve this issue? I also tried zero out /dev/sda2 but it won't help.

My drbd.conf:
global {
usage-count yes;
}

common {
protocol C;
syncer {
rate 40M;
}
}

resource r0 {

on mbus5 {
device /dev/drbd1;
disk /dev/sda2;
address 10.20.40.100:7789;
meta-disk internal;
}
on mbus6 {
device /dev/drbd1;
disk /dev/sda2;
address 10.20.40.81:7789;
meta-disk internal;
}

}

Thanks, Lin

lists at alteeve

Jul 10, 2012, 10:13 PM

Post #2 of 13 (1013 views)
Permalink

Re: Lower device already claimed error [In reply to]

On 07/10/2012 06:54 PM, Lin Zhao wrote:
> Hi I'm setting up drbd on a Linux 2.6.18-238.el5. When I'm doing
> drbdadmin attach, i get error:
>
> //dev/drbd1: Failure: (114) Lower device is already claimed. This
> usually means it is mounted./
> /Command 'drbdsetup /dev/drbd1 disk /dev/sda2 /dev/sda2 internal
> --set-defaults --create-device' terminated with exit code 10/
> /
> /
>
> sda2 should by no means be mounted:
> /[root [at] mbus ~]# mount -l/
> //dev/md1 on / type ext3 (rw,noatime)/
> /proc on /proc type proc (rw)/
> /sysfs on /sys type sysfs (rw)/
> /devpts on /dev/pts type devpts (rw,gid=5,mode=620)/
> //dev/md0 on /boot type ext3 (rw)/
> /tmpfs on /dev/shm type tmpfs (rw)/
> /none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)/

Could it be claimed by LVM or similar? *Something* has it... Any clues
in 'lsof'?

--
Digimer
Papers and Projects: https://alteeve.com

_______________________________________________
drbd-user mailing list
drbd-user [at] lists
http://lists.linbit.com/mailman/listinfo/drbd-user

ff at mpexnet

Jul 11, 2012, 12:34 AM

Post #3 of 13 (1008 views)
Permalink

Re: Lower device already claimed error [In reply to]

On 07/11/2012 07:13 AM, Digimer wrote:
> Could it be claimed by LVM or similar? *Something* has it... Any clues
> in 'lsof'?

...and failing lsof, fuser can be helpful to find the process(es)
blocking the device.
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pascal.berton3 at free

Jul 11, 2012, 1:00 AM

Post #4 of 13 (1012 views)
Permalink

Re: Lower device already claimed error [In reply to]

/dev/sda2 ? Wouldn't it sound like a swap partition or something alike ?
Or wouldn't it be already in use by one of the MDs ?
What does "fdisk -l /dev/sda" return ?

-----Message d'origine-----
De : drbd-user-bounces [at] lists
[mailto:drbd-user-bounces [at] lists] De la part de Digimer
Envoyé : mercredi 11 juillet 2012 07:13
À : Lin Zhao
Cc : drbd-user [at] lists
Objet : Re: [DRBD-user] Lower device already claimed error

On 07/10/2012 06:54 PM, Lin Zhao wrote:
> Hi I'm setting up drbd on a Linux 2.6.18-238.el5. When I'm doing
> drbdadmin attach, i get error:
>
> //dev/drbd1: Failure: (114) Lower device is already claimed. This
> usually means it is mounted./ /Command 'drbdsetup /dev/drbd1 disk
> /dev/sda2 /dev/sda2 internal --set-defaults --create-device'
> terminated with exit code 10/ / /
>
> sda2 should by no means be mounted:
> /[root [at] mbus ~]# mount -l/
> //dev/md1 on / type ext3 (rw,noatime)/ /proc on /proc type proc (rw)/
> /sysfs on /sys type sysfs (rw)/ /devpts on /dev/pts type devpts
> (rw,gid=5,mode=620)/
> //dev/md0 on /boot type ext3 (rw)/
> /tmpfs on /dev/shm type tmpfs (rw)/
> /none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)/

Could it be claimed by LVM or similar? *Something* has it... Any clues in
'lsof'?

--
Digimer
Papers and Projects: https://alteeve.com

_______________________________________________
drbd-user mailing list
drbd-user [at] lists
http://lists.linbit.com/mailman/listinfo/drbd-user

_______________________________________________
drbd-user mailing list
drbd-user [at] lists
http://lists.linbit.com/mailman/listinfo/drbd-user

lin at groupon

Jul 11, 2012, 10:30 AM

Post #5 of 13 (1010 views)
Permalink

Re: Lower device already claimed error [In reply to]

Thanks for the replies. lsof mentions nothing of sda2. Below is fdsk. Any other means to check what might be blocking it?

[root [at] mbus ~]# fdisk -l /dev/sda

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 fd Linux raid autodetect
/dev/sda2 14 117904 946959457+ fd Linux raid autodetect
/dev/sda3 117905 121091 25599577+ fd Linux raid autodetect
/dev/sda4 121092 121601 4096575 fd Linux raid autodetect
[root [at] mbus ~]#

On Jul 11, 2012, at 1:00 AM, Pascal BERTON wrote:

> /dev/sda2 ? Wouldn't it sound like a swap partition or something alike ?
> Or wouldn't it be already in use by one of the MDs ?
> What does "fdisk -l /dev/sda" return ?
>
> -----Message d'origine-----
> De : drbd-user-bounces [at] lists
> [mailto:drbd-user-bounces [at] lists] De la part de Digimer
> Envoyé : mercredi 11 juillet 2012 07:13
> À : Lin Zhao
> Cc : drbd-user [at] lists
> Objet : Re: [DRBD-user] Lower device already claimed error
>
> On 07/10/2012 06:54 PM, Lin Zhao wrote:
>> Hi I'm setting up drbd on a Linux 2.6.18-238.el5. When I'm doing
>> drbdadmin attach, i get error:
>>
>> //dev/drbd1: Failure: (114) Lower device is already claimed. This
>> usually means it is mounted./ /Command 'drbdsetup /dev/drbd1 disk
>> /dev/sda2 /dev/sda2 internal --set-defaults --create-device'
>> terminated with exit code 10/ / /
>>
>> sda2 should by no means be mounted:
>> /[root [at] mbus ~]# mount -l/
>> //dev/md1 on / type ext3 (rw,noatime)/ /proc on /proc type proc (rw)/
>> /sysfs on /sys type sysfs (rw)/ /devpts on /dev/pts type devpts
>> (rw,gid=5,mode=620)/
>> //dev/md0 on /boot type ext3 (rw)/
>> /tmpfs on /dev/shm type tmpfs (rw)/
>> /none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)/
>
> Could it be claimed by LVM or similar? *Something* has it... Any clues in
> 'lsof'?
>
> --
> Digimer
> Papers and Projects: https://alteeve.com
>
>
> _______________________________________________
> drbd-user mailing list
> drbd-user [at] lists
> http://lists.linbit.com/mailman/listinfo/drbd-user
>
> _______________________________________________
> drbd-user mailing list
> drbd-user [at] lists
> http://lists.linbit.com/mailman/listinfo/drbd-user

lists at alteeve

Jul 11, 2012, 10:34 AM

Post #6 of 13 (1010 views)
Permalink

Re: Lower device already claimed error [In reply to]

It's used by RAID, by the looks of it. What does mdadm say? If it is a
RAID member, then you need to specify the /dev/mdX device.

Digimer

On 07/11/2012 01:30 PM, Lin Zhao wrote:
> Thanks for the replies. lsof mentions nothing of sda2. Below is fdsk.
> Any other means to check what might be blocking it?
>
> /[root [at] mbus ~]# fdisk -l /dev/sda/
> /
> /
> /Disk /dev/sda: 1000.2 GB, 1000204886016 bytes/
> /255 heads, 63 sectors/track, 121601 cylinders/
> /Units = cylinders of 16065 * 512 = 8225280 bytes/
> /
> /
> / Device Boot Start End Blocks Id System/
> //dev/sda1 * 1 13 104391 fd Linux raid
> autodetect/
> //dev/sda2 14 117904 946959457+ fd Linux raid
> autodetect/
> //dev/sda3 117905 121091 25599577+ fd Linux raid
> autodetect/
> //dev/sda4 121092 121601 4096575 fd Linux raid
> autodetect/
> /[root [at] mbus ~]# /
>
> On Jul 11, 2012, at 1:00 AM, Pascal BERTON wrote:
>
>> /dev/sda2 ? Wouldn't it sound like a swap partition or something alike ?
>> Or wouldn't it be already in use by one of the MDs ?
>> What does "fdisk -l /dev/sda" return ?
>>
>> -----Message d'origine-----
>> De : drbd-user-bounces [at] lists
>> <mailto:drbd-user-bounces [at] lists>
>> [mailto:drbd-user-bounces [at] lists] De la part de Digimer
>> Envoyé : mercredi 11 juillet 2012 07:13
>> À : Lin Zhao
>> Cc : drbd-user [at] lists <mailto:drbd-user [at] lists>
>> Objet : Re: [DRBD-user] Lower device already claimed error
>>
>> On 07/10/2012 06:54 PM, Lin Zhao wrote:
>>> Hi I'm setting up drbd on a Linux 2.6.18-238.el5. When I'm doing
>>> drbdadmin attach, i get error:
>>>
>>> //dev/drbd1: Failure: (114) Lower device is already claimed. This
>>> usually means it is mounted./ /Command 'drbdsetup /dev/drbd1 disk
>>> /dev/sda2 /dev/sda2 internal --set-defaults --create-device'
>>> terminated with exit code 10/ / /
>>>
>>> sda2 should by no means be mounted:
>>> /[root [at] mbus ~]# mount -l/
>>> //dev/md1 on / type ext3 (rw,noatime)/ /proc on /proc type proc (rw)/
>>> /sysfs on /sys type sysfs (rw)/ /devpts on /dev/pts type devpts
>>> (rw,gid=5,mode=620)/
>>> //dev/md0 on /boot type ext3 (rw)/
>>> /tmpfs on /dev/shm type tmpfs (rw)/
>>> /none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)/
>>
>> Could it be claimed by LVM or similar? *Something* has it... Any clues in
>> 'lsof'?
>>
>> --
>> Digimer
>> Papers and Projects: https://alteeve.com
>>
>>
>> _______________________________________________
>> drbd-user mailing list
>> drbd-user [at] lists <mailto:drbd-user [at] lists>
>> http://lists.linbit.com/mailman/listinfo/drbd-user
>>
>> _______________________________________________
>> drbd-user mailing list
>> drbd-user [at] lists
>> http://lists.linbit.com/mailman/listinfo/drbd-user
>
>
>
> _______________________________________________
> drbd-user mailing list
> drbd-user [at] lists
> http://lists.linbit.com/mailman/listinfo/drbd-user
>

--
Digimer
Papers and Projects: https://alteeve.com

_______________________________________________
drbd-user mailing list
drbd-user [at] lists
http://lists.linbit.com/mailman/listinfo/drbd-user

lin at groupon

Jul 11, 2012, 10:49 AM

Post #7 of 13 (1006 views)
Permalink

Re: Lower device already claimed error [In reply to]

I think we've found the cause here. Below is the mdadm output. Should we use /dev/md2 instead of sda2 in the drbd conf?

[root [at] mbus ~]# mdadm --misc -D /dev/md2
/dev/md2:
Version : 0.90
Creation Time : Tue Nov 29 18:25:35 2011
Raid Level : raid10
Array Size : 1893918720 (1806.18 GiB 1939.37 GB)
Used Dev Size : 946959360 (903.09 GiB 969.69 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 2
Persistence : Superblock is persistent

Update Time : Fri Jul 6 22:09:18 2012
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0

Layout : near=2
Chunk Size : 256K

UUID : c4bc887b:ba1a9809:d90d1802:034ea8a8
Events : 0.8

Number Major Minor RaidDevice State
0 8 2 0 active sync /dev/sda2
1 8 18 1 active sync /dev/sdb2
2 8 34 2 active sync /dev/sdc2
3 8 50 3 active sync /dev/sdd2

On Jul 11, 2012, at 10:34 AM, Digimer wrote:

> It's used by RAID, by the looks of it. What does mdadm say? If it is a
> RAID member, then you need to specify the /dev/mdX device.
>
> Digimer
>
> On 07/11/2012 01:30 PM, Lin Zhao wrote:
>> Thanks for the replies. lsof mentions nothing of sda2. Below is fdsk.
>> Any other means to check what might be blocking it?
>>
>> /[root [at] mbus ~]# fdisk -l /dev/sda/
>> /
>> /
>> /Disk /dev/sda: 1000.2 GB, 1000204886016 bytes/
>> /255 heads, 63 sectors/track, 121601 cylinders/
>> /Units = cylinders of 16065 * 512 = 8225280 bytes/
>> /
>> /
>> / Device Boot Start End Blocks Id System/
>> //dev/sda1 * 1 13 104391 fd Linux raid
>> autodetect/
>> //dev/sda2 14 117904 946959457+ fd Linux raid
>> autodetect/
>> //dev/sda3 117905 121091 25599577+ fd Linux raid
>> autodetect/
>> //dev/sda4 121092 121601 4096575 fd Linux raid
>> autodetect/
>> /[root [at] mbus ~]# /
>>
>> On Jul 11, 2012, at 1:00 AM, Pascal BERTON wrote:
>>
>>> /dev/sda2 ? Wouldn't it sound like a swap partition or something alike ?
>>> Or wouldn't it be already in use by one of the MDs ?
>>> What does "fdisk -l /dev/sda" return ?
>>>
>>> -----Message d'origine-----
>>> De : drbd-user-bounces [at] lists
>>> <mailto:drbd-user-bounces [at] lists>
>>> [mailto:drbd-user-bounces [at] lists] De la part de Digimer
>>> Envoyé : mercredi 11 juillet 2012 07:13
>>> À : Lin Zhao
>>> Cc : drbd-user [at] lists <mailto:drbd-user [at] lists>
>>> Objet : Re: [DRBD-user] Lower device already claimed error
>>>
>>> On 07/10/2012 06:54 PM, Lin Zhao wrote:
>>>> Hi I'm setting up drbd on a Linux 2.6.18-238.el5. When I'm doing
>>>> drbdadmin attach, i get error:
>>>>
>>>> //dev/drbd1: Failure: (114) Lower device is already claimed. This
>>>> usually means it is mounted./ /Command 'drbdsetup /dev/drbd1 disk
>>>> /dev/sda2 /dev/sda2 internal --set-defaults --create-device'
>>>> terminated with exit code 10/ / /
>>>>
>>>> sda2 should by no means be mounted:
>>>> /[root [at] mbus ~]# mount -l/
>>>> //dev/md1 on / type ext3 (rw,noatime)/ /proc on /proc type proc (rw)/
>>>> /sysfs on /sys type sysfs (rw)/ /devpts on /dev/pts type devpts
>>>> (rw,gid=5,mode=620)/
>>>> //dev/md0 on /boot type ext3 (rw)/
>>>> /tmpfs on /dev/shm type tmpfs (rw)/
>>>> /none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)/
>>>
>>> Could it be claimed by LVM or similar? *Something* has it... Any clues in
>>> 'lsof'?
>>>
>>> --
>>> Digimer
>>> Papers and Projects: https://alteeve.com
>>>
>>>
>>> _______________________________________________
>>> drbd-user mailing list
>>> drbd-user [at] lists <mailto:drbd-user [at] lists>
>>> http://lists.linbit.com/mailman/listinfo/drbd-user
>>>
>>> _______________________________________________
>>> drbd-user mailing list
>>> drbd-user [at] lists
>>> http://lists.linbit.com/mailman/listinfo/drbd-user
>>
>>
>>
>> _______________________________________________
>> drbd-user mailing list
>> drbd-user [at] lists
>> http://lists.linbit.com/mailman/listinfo/drbd-user
>>
>
>
> --
> Digimer
> Papers and Projects: https://alteeve.com
>
>

lists at alteeve

Jul 11, 2012, 12:20 PM

Post #8 of 13 (1001 views)
Permalink

Re: Lower device already claimed error [In reply to]

I would guess so, but you know your system better than us. I can't see
any reason though why you would want to use a single RAID member as a
DRBD device... Using the RAID device makes a lot more sense.

On 07/11/2012 01:49 PM, Lin Zhao wrote:
> I think we've found the cause here. Below is the mdadm output. Should we
> use /dev/md2 instead of sda2 in the drbd conf?
> /
> /
> /[root [at] mbus ~]# mdadm --misc -D /dev/md2/
> //dev/md2:/
> / Version : 0.90/
> / Creation Time : Tue Nov 29 18:25:35 2011/
> / Raid Level : raid10/
> / Array Size : 1893918720 (1806.18 GiB 1939.37 GB)/
> / Used Dev Size : 946959360 (903.09 GiB 969.69 GB)/
> / Raid Devices : 4/
> / Total Devices : 4/
> /Preferred Minor : 2/
> / Persistence : Superblock is persistent/
> /
> /
> / Update Time : Fri Jul 6 22:09:18 2012/
> / State : clean/
> / Active Devices : 4/
> /Working Devices : 4/
> / Failed Devices : 0/
> / Spare Devices : 0/
> /
> /
> / Layout : near=2/
> / Chunk Size : 256K/
> /
> /
> / UUID : c4bc887b:ba1a9809:d90d1802:034ea8a8/
> / Events : 0.8/
> /
> /
> / Number Major Minor RaidDevice State/
> / 0 8 2 0 active sync /dev/sda2/
> / 1 8 18 1 active sync /dev/sdb2/
> / 2 8 34 2 active sync /dev/sdc2/
> / 3 8 50 3 active sync /dev/sdd2/
>
>
> On Jul 11, 2012, at 10:34 AM, Digimer wrote:
>
>> It's used by RAID, by the looks of it. What does mdadm say? If it is a
>> RAID member, then you need to specify the /dev/mdX device.
>>
>> Digimer
>>
>> On 07/11/2012 01:30 PM, Lin Zhao wrote:
>>> Thanks for the replies. lsof mentions nothing of sda2. Below is fdsk.
>>> Any other means to check what might be blocking it?
>>>
>>> /[root [at] mbus ~]# fdisk -l /dev/sda/
>>> /
>>> /
>>> /Disk /dev/sda: 1000.2 GB, 1000204886016 bytes/
>>> /255 heads, 63 sectors/track, 121601 cylinders/
>>> /Units = cylinders of 16065 * 512 = 8225280 bytes/
>>> /
>>> /
>>> / Device Boot Start End Blocks Id System/
>>> //dev/sda1 * 1 13 104391 fd Linux raid
>>> autodetect/
>>> //dev/sda2 14 117904 946959457+ fd Linux raid
>>> autodetect/
>>> //dev/sda3 117905 121091 25599577+ fd Linux raid
>>> autodetect/
>>> //dev/sda4 121092 121601 4096575 fd Linux raid
>>> autodetect/
>>> /[root [at] mbus ~]# /
>>>
>>> On Jul 11, 2012, at 1:00 AM, Pascal BERTON wrote:
>>>
>>>> /dev/sda2 ? Wouldn't it sound like a swap partition or something alike ?
>>>> Or wouldn't it be already in use by one of the MDs ?
>>>> What does "fdisk -l /dev/sda" return ?
>>>>
>>>> -----Message d'origine-----
>>>> De : drbd-user-bounces [at] lists
>>>> <mailto:drbd-user-bounces [at] lists>
>>>> <mailto:drbd-user-bounces [at] lists>
>>>> [mailto:drbd-user-bounces [at] lists] De la part de Digimer
>>>> Envoyé : mercredi 11 juillet 2012 07:13
>>>> À : Lin Zhao
>>>> Cc : drbd-user [at] lists <mailto:drbd-user [at] lists>
>>>> <mailto:drbd-user [at] lists>
>>>> Objet : Re: [DRBD-user] Lower device already claimed error
>>>>
>>>> On 07/10/2012 06:54 PM, Lin Zhao wrote:
>>>>> Hi I'm setting up drbd on a Linux 2.6.18-238.el5. When I'm doing
>>>>> drbdadmin attach, i get error:
>>>>>
>>>>> //dev/drbd1: Failure: (114) Lower device is already claimed. This
>>>>> usually means it is mounted./ /Command 'drbdsetup /dev/drbd1 disk
>>>>> /dev/sda2 /dev/sda2 internal --set-defaults --create-device'
>>>>> terminated with exit code 10/ / /
>>>>>
>>>>> sda2 should by no means be mounted:
>>>>> /[root [at] mbus ~]# mount -l/
>>>>> //dev/md1 on / type ext3 (rw,noatime)/ /proc on /proc type proc (rw)/
>>>>> /sysfs on /sys type sysfs (rw)/ /devpts on /dev/pts type devpts
>>>>> (rw,gid=5,mode=620)/
>>>>> //dev/md0 on /boot type ext3 (rw)/
>>>>> /tmpfs on /dev/shm type tmpfs (rw)/
>>>>> /none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)/
>>>>
>>>> Could it be claimed by LVM or similar? *Something* has it... Any
>>>> clues in
>>>> 'lsof'?
>>>>
>>>> --
>>>> Digimer
>>>> Papers and Projects: https://alteeve.com
>>>>
>>>>
>>>> _______________________________________________
>>>> drbd-user mailing list
>>>> drbd-user [at] lists <mailto:drbd-user [at] lists>
>>>> <mailto:drbd-user [at] lists>
>>>> http://lists.linbit.com/mailman/listinfo/drbd-user
>>>>
>>>> _______________________________________________
>>>> drbd-user mailing list
>>>> drbd-user [at] lists <mailto:drbd-user [at] lists>
>>>> http://lists.linbit.com/mailman/listinfo/drbd-user
>>>
>>>
>>>
>>> _______________________________________________
>>> drbd-user mailing list
>>> drbd-user [at] lists <mailto:drbd-user [at] lists>
>>> http://lists.linbit.com/mailman/listinfo/drbd-user
>>>
>>
>>
>> --
>> Digimer
>> Papers and Projects: https://alteeve.com
>>
>>
>

--
Digimer
Papers and Projects: https://alteeve.com

_______________________________________________
drbd-user mailing list
drbd-user [at] lists
http://lists.linbit.com/mailman/listinfo/drbd-user

arnold at arnoldarts

Jul 11, 2012, 1:07 PM

Post #9 of 13 (1002 views)
Permalink

Re: Lower device already claimed error [In reply to]

On 11.07.2012 21:20, Digimer wrote:
> I would guess so, but you know your system better than us. I can't see
> any reason though why you would want to use a single RAID member as a
> DRBD device... Using the RAID device makes a lot more sense.

What if someone uses one leg of an software-raid1 as a disk for drbd on
machine a and mounts the physical device of the same drbd on machine b?

From the don't-do-this-at-home-department,

Arnold--
Dieses Email wurde elektronisch erstellt und ist ohne handschriftliche
Unterschrift gÃ¼ltig.

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lists at alteeve

Jul 11, 2012, 1:12 PM

Post #10 of 13 (1004 views)
Permalink

Re: Lower device already claimed error [In reply to]

On 07/11/2012 04:07 PM, Arnold Krille wrote:
> On 11.07.2012 21:20, Digimer wrote:
>> I would guess so, but you know your system better than us. I can't see
>> any reason though why you would want to use a single RAID member as a
>> DRBD device... Using the RAID device makes a lot more sense.
>
> What if someone uses one leg of an software-raid1 as a disk for drbd on
> machine a and mounts the physical device of the same drbd on machine b?
>
> From the don't-do-this-at-home-department,
>
> Arnold--

You simply couldn't. The device would be a member of the array and,
thus, DRBD will refuse to use it, as Lin has seen. Forcing the issue
would be kind of like having one person pushing the gas and brakes on a
car while another person steered, with no real coordination between the
two.

As the kids say these day, "you'll have a bad time".

--
Digimer
Papers and Projects: https://alteeve.com

_______________________________________________
drbd-user mailing list
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http://lists.linbit.com/mailman/listinfo/drbd-user

arnold at arnoldarts

Jul 11, 2012, 1:19 PM

Post #11 of 13 (1011 views)
Permalink

Re: Lower device already claimed error [In reply to]

On 11.07.2012 22:12, Digimer wrote:
> On 07/11/2012 04:07 PM, Arnold Krille wrote:
>> On 11.07.2012 21:20, Digimer wrote:
>>> I would guess so, but you know your system better than us. I can't see
>>> any reason though why you would want to use a single RAID member as a
>>> DRBD device... Using the RAID device makes a lot more sense.
>>
>> What if someone uses one leg of an software-raid1 as a disk for drbd on
>> machine a and mounts the physical device of the same drbd on machine b?
>>
>> From the don't-do-this-at-home-department,
>
> You simply couldn't. The device would be a member of the array and,
> thus, DRBD will refuse to use it, as Lin has seen. Forcing the issue
> would be kind of like having one person pushing the gas and brakes on a
> car while another person steered, with no real coordination between the
> two.
>
> As the kids say these day, "you'll have a bad time".

So, once again I forgot to add the funny-markers...

On a serious note, if I remember correctly drbd saves its "this is a
drbd-device" information at the end of the partition (if at all), so
when you plug the disk into a different machine and just want to access
the data, its the same as with md (with metadata=0.99): Just mount the
partition.

Arnold
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Jul 11, 2012, 1:27 PM

Post #12 of 13 (1004 views)
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Re: Lower device already claimed error [In reply to]

On 07/11/2012 04:19 PM, Arnold Krille wrote:
> On 11.07.2012 22:12, Digimer wrote:
>> On 07/11/2012 04:07 PM, Arnold Krille wrote:
>>> On 11.07.2012 21:20, Digimer wrote:
>>>> I would guess so, but you know your system better than us. I can't see
>>>> any reason though why you would want to use a single RAID member as a
>>>> DRBD device... Using the RAID device makes a lot more sense.
>>>
>>> What if someone uses one leg of an software-raid1 as a disk for drbd on
>>> machine a and mounts the physical device of the same drbd on machine b?
>>>
>>> From the don't-do-this-at-home-department,
>>
>> You simply couldn't. The device would be a member of the array and,
>> thus, DRBD will refuse to use it, as Lin has seen. Forcing the issue
>> would be kind of like having one person pushing the gas and brakes on a
>> car while another person steered, with no real coordination between the
>> two.
>>
>> As the kids say these day, "you'll have a bad time".
>
> So, once again I forgot to add the funny-markers...
>
> On a serious note, if I remember correctly drbd saves its "this is a
> drbd-device" information at the end of the partition (if at all), so
> when you plug the disk into a different machine and just want to access
> the data, its the same as with md (with metadata=0.99): Just mount the
> partition.
>
> Arnold

I figured you were kidding around, but I thought it a good chance to
throw the answer into the archives. :)

The metadata, when "internal", does get written to the end of the
backing devices. You can mount the raw device, but of course, few if any
FS will know what that metadata is, so it could well be scrogged.
Mounting a backing device read-only *should* be safe, but I haven't
tried it myself.

--
Digimer
Papers and Projects: https://alteeve.com

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ff at mpexnet

Jul 12, 2012, 1:42 AM

Post #13 of 13 (989 views)
Permalink

Re: Lower device already claimed error [In reply to]

On 07/11/2012 10:27 PM, Digimer wrote:
> The metadata, when "internal", does get written to the end of the
> backing devices. You can mount the raw device, but of course, few if any
> FS will know what that metadata is, so it could well be scrogged.
> Mounting a backing device read-only *should* be safe, but I haven't
> tried it myself.

Not entirely wrong, but not the real problem, either.

A filesystem on a valid drbd backing device will be smaller than or
equal to ( raw dev size - metadata size ). Mounting this in and of
itself poses no problem, and the metadata will remain untouched.

Of course, now your quicksync bitmap (in the metadata) is out of sync
with the actual data. Whatever gets written while you bypass drbd will
be, well, unknown to drbd. So if you resume drbd operation at a later
point, there will be changed blocks on your disk that drbd won't see a
need to sync to its peer. If no verify is performed, you keep running an
inconsistent resource (until by chance all those sectors are overwritten
again and thus synced after all).

That's my understanding, at least :-)

Cheers,
Felix
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