Bug 199778

Summary: lvmdiskscan lists LVs when it should be confined to disks/PVs
Product: Red Hat Enterprise Linux 4 Reporter: Mike Snitzer <snitzer>
Component: lvm2Assignee: Alasdair Kergon <agk>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: 4.0CC: mbroz
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Hardware: All   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2006-07-21 22:18:46 UTC Type: ---
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Description Mike Snitzer 2006-07-21 21:38:53 UTC 
Description of problem:
Using:  filter = [ "r/dev/mapper*.*/", "r/dev/dm*.*/", "a/.*/" ] will cause
Logical volumes to be displayed in the lvmdiskscan output

Version-Release number of selected component (if applicable):
  LVM version:     2.02.01 (2005-11-23)
  Library version: 1.02.02 (2006-01-04)
  Driver version:  4.5.0

How reproducible:
Always

Steps to Reproduce:
1. create an LV
2. use lvm.conf filter: filter = [ "r/dev/mapper*.*/", "r/dev/dm*.*/", "a/.*/" ] 
3. run lvmdiskscan
  
Actual results:
will display LVs as if they were PVs

Expected results:
lvmdiskscan shouldn't _ever_ display an LV (or associated DM devices) as if it
were a disk/PV.

Additional info:

All of the following variants cause lvmdiskscan to display none disks
(/dev/mapper*, /dev/dm-*, /dev/<VG>/<LV>) as disks:

using above filter:
# lvmdiskscan
  /dev/sdq                 [       10.00 GB] LVM physical volume
  /dev/root                [       65.66 GB]
  /dev/sda1                [      101.94 MB]
  /dev/VolGroup00/LogVol01 [        1.94 GB]
  /dev/sda2                [       33.81 GB] LVM physical volume
  /dev/vg01/lvol0          [        9.00 GB]
  /dev/vg1/lvg1            [        9.97 GB]
  /dev/vg2/lvg2            [        9.97 GB]
  /dev/vg3/lvg3            [        9.97 GB]
  /dev/vg4/lvg4            [        9.97 GB]
  /dev/sdr                 [       10.00 GB] LVM physical volume
  /dev/sdb1                [       33.91 GB] LVM physical volume
  /dev/sdc                 [       10.00 GB] LVM physical volume
  /dev/sdd                 [       10.00 GB] LVM physical volume
  1 disk
  7 partitions
  4 LVM physical volume whole disks
  2 LVM physical volumes

using: filter = [ "r/dev/mapper*.*/", "a/.*/" ]
# lvmdiskscan
  /dev/sdq  [       10.00 GB] LVM physical volume
  /dev/root [       65.66 GB]
  /dev/sda1 [      101.94 MB]
  /dev/dm-1 [        1.94 GB]
  /dev/sda2 [       33.81 GB] LVM physical volume
  /dev/dm-2 [        9.00 GB]
  /dev/dm-3 [        9.97 GB]
  /dev/dm-4 [        9.97 GB]
  /dev/dm-5 [        9.97 GB]
  /dev/dm-6 [        9.97 GB]
  /dev/sdr  [       10.00 GB] LVM physical volume
  /dev/sdb1 [       33.91 GB] LVM physical volume
  /dev/sdc  [       10.00 GB] LVM physical volume
  /dev/sdd  [       10.00 GB] LVM physical volume
  1 disk
  7 partitions
  4 LVM physical volume whole disks
  2 LVM physical volumes

using: filter = [ "r/dev/dm*.*/", "a/.*/" ]
# lvmdiskscan
  /dev/sdq                        [       10.00 GB] LVM physical volume
  /dev/root                       [       65.66 GB]
  /dev/sda1                       [      101.94 MB]
  /dev/mapper/VolGroup00-LogVol01 [        1.94 GB]
  /dev/sda2                       [       33.81 GB] LVM physical volume
  /dev/mapper/vg01-lvol0          [        9.00 GB]
  /dev/mapper/vg1-lvg1            [        9.97 GB]
  /dev/mapper/vg2-lvg2            [        9.97 GB]
  /dev/mapper/vg3-lvg3            [        9.97 GB]
  /dev/mapper/vg4-lvg4            [        9.97 GB]
  /dev/sdr                        [       10.00 GB] LVM physical volume
  /dev/sdb1                       [       33.91 GB] LVM physical volume
  /dev/sdc                        [       10.00 GB] LVM physical volume
  /dev/sdd                        [       10.00 GB] LVM physical volume
  1 disk
  7 partitions
  4 LVM physical volume whole disks
  2 LVM physical volumes

This filter at least masks all none disks/PVs; its unfortunate lvmdiskscan
doesn't report this without help.

using: filter = [ "r/dev/mapper*.*/", "r/dev/dm*.*/" ]
# lvmdiskscan
  /dev/sdq  [       10.00 GB] LVM physical volume
  /dev/sda1 [      101.94 MB]
  /dev/sda2 [       33.81 GB] LVM physical volume
  /dev/sdr  [       10.00 GB] LVM physical volume
  /dev/sdb1 [       33.91 GB] LVM physical volume
  /dev/sdc  [       10.00 GB] LVM physical volume
  /dev/sdd  [       10.00 GB] LVM physical volume
  0 disks
  1 partition
  4 LVM physical volume whole disks
  2 LVM physical volumes
Comment 1 Alasdair Kergon 2006-07-21 22:18:46 UTC 
You are allowed to stack devices: LVs *can* be used as PVs.
Comment 2 Alasdair Kergon 2006-07-21 22:26:24 UTC 
Consider for example creating a VG containing striped (or eventually mirrored)
LVs, then creating PVs on the LVs and putting them into a new VG in which all
the storage, whatever it is allocated to subsequently, is automatically striped
(or mirrored).