[linux-lvm] Problem with vgscan and md

[linux-lvm] Problem with vgscan and md

[Luca Berra]

Hello,
I found a probable bug in vgscan up to LVM 1.0.5 due to lv device nodes 
renumbering

i found the problem in a shared storage environment, but it can be 
reproduced on a single machine

the problem can be reproduced with 2 md devices
create 2 vg each composed of 1 md device
let's say
VG /dev/vg00
Device 109:0
LV /dev/vg00/lvol1
Device 58:0
LV /dev/vg00/lvol2
Device 58:1
LV /dev/vg00/lvol3
Device 58:2
PV /dev/md0

VG /dev/vg01
Device 109:1
LV /dev/vg01/lvol1
Device 58:3
LV /dev/vg01/lvol2
Device 58:4
LV /dev/vg01/lvol3
Device 58:5
PV /dev/md1

now deactivate all VGs
raidstop /dev/md0
run vgscan -v

you have

VG /dev/vg01
Device 109:0
LV /dev/vg01/lvol1
Device 58:0
LV /dev/vg01/lvol2
Device 58:1
LV /dev/vg01/lvol3
Device 58:2
PV /dev/md1

vgchange -a y /dev/vg01

now raidstart /dev/md0

you need to run vgcan again, to see vg00

vgscan renumbers device node for vg00 so you get

VG /dev/vg00
Device 109:0
LV /dev/vg00/lvol1
Device 58:0
LV /dev/vg00/lvol2
Device 58:1
LV /dev/vg00/lvol3
Device 58:2
PV /dev/md0

vgscan cannot renumber device nodes for vg01 (which is active) so you 
also get

VG /dev/vg01
Device 109:0
LV /dev/vg01/lvol1
Device 58:0
LV /dev/vg01/lvol2
Device 58:1
LV /dev/vg01/lvol3
Device 58:2
PV /dev/md1

so we got two DIFFERENT vgs with the SAME device files

the need to run vgscan is due to having a shared storage so i might want 
to activate the md devices and vg devices on different nodes

Regards,
Luca


-- 
Luca Berra -- bluca@comedia.it

Re: [linux-lvm] Problem with vgscan and md

[Heinz J . Mauelshagen]

Luca,

I tried to reproduce this here with the 1.0.5 and failed.

1.0.5 vgscan only changes minors if there's minor # clashes _and_ if it
is run with option "-f" in order to keep minors persistent by default.

So I deativated all VGs and stopped the device for the first one.
There was no reason for vgscan to reallocate the device minors because
there's no clash. After starting the device again and running vgscan,
both VGs were accessable fine.

An automatic reallocation of device numbers took place in vgscan up
to version 1.0.
Maybe this is an older tool version?

Regards,
Heinz    -- The LVM Guy --

On Wed, Oct 09, 2002 at 06:13:49PM +0200, Luca Berra wrote:
> Hello,
> I found a probable bug in vgscan up to LVM 1.0.5 due to lv device nodes 
> renumbering
> 
> i found the problem in a shared storage environment, but it can be 
> reproduced on a single machine
> 
> the problem can be reproduced with 2 md devices
> create 2 vg each composed of 1 md device
> let's say
> VG /dev/vg00
> Device 109:0
> LV /dev/vg00/lvol1
> Device 58:0
> LV /dev/vg00/lvol2
> Device 58:1
> LV /dev/vg00/lvol3
> Device 58:2
> PV /dev/md0
> 
> VG /dev/vg01
> Device 109:1
> LV /dev/vg01/lvol1
> Device 58:3
> LV /dev/vg01/lvol2
> Device 58:4
> LV /dev/vg01/lvol3
> Device 58:5
> PV /dev/md1
> 
> now deactivate all VGs
> raidstop /dev/md0
> run vgscan -v
> 
> you have
> 
> VG /dev/vg01
> Device 109:0
> LV /dev/vg01/lvol1
> Device 58:0
> LV /dev/vg01/lvol2
> Device 58:1
> LV /dev/vg01/lvol3
> Device 58:2
> PV /dev/md1
> 
> vgchange -a y /dev/vg01
> 
> now raidstart /dev/md0
> 
> you need to run vgcan again, to see vg00
> 
> vgscan renumbers device node for vg00 so you get
> 
> VG /dev/vg00
> Device 109:0
> LV /dev/vg00/lvol1
> Device 58:0
> LV /dev/vg00/lvol2
> Device 58:1
> LV /dev/vg00/lvol3
> Device 58:2
> PV /dev/md0
> 
> vgscan cannot renumber device nodes for vg01 (which is active) so you 
> also get
> 
> VG /dev/vg01
> Device 109:0
> LV /dev/vg01/lvol1
> Device 58:0
> LV /dev/vg01/lvol2
> Device 58:1
> LV /dev/vg01/lvol3
> Device 58:2
> PV /dev/md1
> 
> so we got two DIFFERENT vgs with the SAME device files
> 
> the need to run vgscan is due to having a shared storage so i might want 
> to activate the md devices and vg devices on different nodes
> 
> Regards,
> Luca
> 
> 
> -- 
> Luca Berra -- bluca@comedia.it
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

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Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
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