[linux-lvm] dev node change

[linux-lvm] dev node change

[Umar Draz]

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Hi All

I have a SCSI share which i am  using linux initiator on my ubuntu. Its
available for me in /dev/sdb

No I have created lvm group using the /dev/sdb. Today I just logut and
login my scsi share but this time ubutnu gave me this as /dev/sdc instead
of /dev/sdb.

due to this my lvm group is stuck, and its giving me the error

Input/output error

on pvdisplay or vgdisplay,

Any body help me how I can reslove this issue.?

Br.

Umar

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Re: [linux-lvm] dev node change

[Peter Rajnoha]

On 12/09/2013 04:13 PM, Umar Draz wrote:
> Hi All
> 
> I have a SCSI share which i am  using linux initiator on my ubuntu. Its
> available for me in /dev/sdb
> 
> No I have created lvm group using the /dev/sdb. Today I just logut and
> login my scsi share but this time ubutnu gave me this as /dev/sdc
> instead of /dev/sdb.
> 
> due to this my lvm group is stuck, and its giving me the error
> 
> Input/output error
> 
> on pvdisplay or vgdisplay,
> 
> Any body help me how I can reslove this issue.?
> 

You should always deactivate your LVM volumes before
disconnecting the underlying iSCSI volumes and then when
you reconnect the iSCSI back, activate the LVM volumes
(or if autoactivation is used - meaning use_lvmetad=1
is set in lvm.conf, this activation happens automatically).

Alternatively, you can call vgchange --refresh when the
iSCSI is connected back.

-- 
Peter

Re: [linux-lvm] dev node change

[Alessandro MACUZ]

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2013/12/10 Peter Rajnoha <prajnoha@redhat.com>

> On 12/09/2013 04:13 PM, Umar Draz wrote:
> > Hi All
> >
> > I have a SCSI share which i am  using linux initiator on my ubuntu. Its
> > available for me in /dev/sdb
> >
> > No I have created lvm group using the /dev/sdb. Today I just logut and
> > login my scsi share but this time ubutnu gave me this as /dev/sdc
> > instead of /dev/sdb.
> >
> > due to this my lvm group is stuck, and its giving me the error
> >
> > Input/output error
> >
> > on pvdisplay or vgdisplay,
> >
> > Any body help me how I can reslove this issue.?
> >
>
> You should always deactivate your LVM volumes before
> disconnecting the underlying iSCSI volumes and then when
> you reconnect the iSCSI back, activate the LVM volumes
> (or if autoactivation is used - meaning use_lvmetad=1
> is set in lvm.conf, this activation happens automatically).
>
> Alternatively, you can call vgchange --refresh when the
> iSCSI is connected back.



Couldn't be used the identification of PV by UUID here? It should be better
imo.

Alex

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Re: [linux-lvm] dev node change

[Peter Rajnoha]

On 12/10/2013 03:33 PM, Alessandro MACUZ wrote:
> 2013/12/10 Peter Rajnoha <prajnoha@redhat.com <mailto:prajnoha@redhat.com>>
> 
>     On 12/09/2013 04:13 PM, Umar Draz wrote:
>     > Hi All
>     >
>     > I have a SCSI share which i am  using linux initiator on my
>     ubuntu. Its
>     > available for me in /dev/sdb
>     >
>     > No I have created lvm group using the /dev/sdb. Today I just logut and
>     > login my scsi share but this time ubutnu gave me this as /dev/sdc
>     > instead of /dev/sdb.
>     >
>     > due to this my lvm group is stuck, and its giving me the error
>     >
>     > Input/output error
>     >
>     > on pvdisplay or vgdisplay,
>     >
>     > Any body help me how I can reslove this issue.?
>     >
> 
>     You should always deactivate your LVM volumes before
>     disconnecting the underlying iSCSI volumes and then when
>     you reconnect the iSCSI back, activate the LVM volumes
>     (or if autoactivation is used - meaning use_lvmetad=1
>     is set in lvm.conf, this activation happens automatically).
> 
>     Alternatively, you can call vgchange --refresh when the
>     iSCSI is connected back.
> 
> 
> 
> Couldn't be used the identification of PV by UUID here? It should be
> better imo.
> 

Well, this is about dm tables that represent the logical volumes
(you can check dmsetup table output). The PV UUID doesn't play a role
at this level - the PV UUID is just LVM abstraction that is using
device-mapper kernel capabilities.

And if the iSCSI is disconnected while there's anything on top of it
(in this case the LV), the major:minor pair (as well as the kernel name)
is reserved until all the stack above it is freed.

Then when the iSCSI is connected back (while the old major:minor is
still held by old mapping), kernel has no other choice just to assign
new major:minor pair. Therefore we need a refresh (or deactivation/activation)
which will generate a new mapping with the new major:minor pair of the
underlying PV (the iSCSI volume).
-- 
Peter

Re: [linux-lvm] dev node change

[Umar Draz]

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Hi Alex,

Thanks for this. :)

Br.

Umar


On Tue, Dec 10, 2013 at 7:33 PM, Alessandro MACUZ <
alessandro.macuz@gmail.com> wrote:

> 2013/12/10 Peter Rajnoha <prajnoha@redhat.com>
>
>> On 12/09/2013 04:13 PM, Umar Draz wrote:
>> > Hi All
>> >
>> > I have a SCSI share which i am  using linux initiator on my ubuntu. Its
>> > available for me in /dev/sdb
>> >
>> > No I have created lvm group using the /dev/sdb. Today I just logut and
>> > login my scsi share but this time ubutnu gave me this as /dev/sdc
>> > instead of /dev/sdb.
>> >
>> > due to this my lvm group is stuck, and its giving me the error
>> >
>> > Input/output error
>> >
>> > on pvdisplay or vgdisplay,
>> >
>> > Any body help me how I can reslove this issue.?
>> >
>>
>> You should always deactivate your LVM volumes before
>> disconnecting the underlying iSCSI volumes and then when
>> you reconnect the iSCSI back, activate the LVM volumes
>> (or if autoactivation is used - meaning use_lvmetad=1
>> is set in lvm.conf, this activation happens automatically).
>>
>> Alternatively, you can call vgchange --refresh when the
>> iSCSI is connected back.
>
>
>
> Couldn't be used the identification of PV by UUID here? It should be
> better imo.
>
> Alex
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>



-- 
Umar Draz
Network Architect

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