Tag Archives: odm

Altering LVM Configuration When a Disk is Not in ODM Anymore

If you remove a disk from the system using rmdev -dl hdiskX without having previously reduced the volume group to remove the disk from LVM, and thus have not updated properly the on-disk format information (called VGDA), you get a discrepancy between the ODM and the LVM configurations. Here is how to solve the issue (without any warranty though!).

What are the volume group informations:

# lsvg -p rootvg
rootvg:
PV_NAME           PV STATE          TOTAL PPs   FREE PPs    FREE DISTRIBUTION
hdisk0            active            2157        1019        174..00..00..413..432
0516-304 : Unable to find device id 00ce4b6a01292201 in the Device
       Configuration Database.
00ce4b6a01292201  missing           2157        1019        174..71..00..342..432
# lspv
hdisk0          00ce4b6ade6da849                    rootvg          active
hdisk2          00ce4b6a01b09b83                    drakevg         active
hdisk3          00ce4b6afd175206                    drakevg         active
# lsdev -Cc disk
hdisk0 Available  Virtual SCSI Disk Drive
hdisk2 Available  Virtual SCSI Disk Drive
hdisk3 Available  Virtual SCSI Disk Drive

As we can notice, the disk is still in the LVM configuration but doesn’t show up in the devices. To solve this issue, we need to cheat the ODM in order to be able to use LVM commands to change the LVM configuration, stored on the volume group disks. The idea is to reinsert a disk in the ODM configuration, remove the disk from LVM and then remove it from ODM. Here is how we do it. First, let’s make a copy of the ODM files that we will change:

# cd /etc/objrepos/
# cp CuAt CuAt.before_cheat
# cp CuDv CuDv.before_cheat
# cp CuPath CuPath.before_cheat

Now, we will extract the hdisk0‘s definition from ODM and add it back as hdisk1‘s definition:

# odmget -q "name=hdisk0" CuAt
CuAt:
       name = "hdisk0"
       attribute = "unique_id"
       value = "3520200946033223609SYMMETRIX03EMCfcp05VDASD03AIXvscsi"
       type = "R"
       generic = ""
       rep = "n"
       nls_index = 0
CuAt:
       name = "hdisk0"
       attribute = "pvid"
       value = "00ce4b6ade6da8490000000000000000"
       type = "R"
       generic = "D"
       rep = "s"
       nls_index = 11
# odmget -q "name=hdisk0" CuDv
CuDv:
       name = "hdisk0"
       status = 1
       chgstatus = 2
       ddins = "scsidisk"
       location = ""
       parent = "vscsi0"
       connwhere = "810000000000"
       PdDvLn = "disk/vscsi/vdisk"
# odmget -q "name=hdisk0" CuPath
CuPath:
       name = "hdisk0"
       parent = "vscsi0"
       connection = "810000000000"
       alias = ""
       path_status = 1
       path_id = 0

Basically, we need to insert new entries in the three classes CuAt, CuDv and CuPath with hdisk0 changed to hdisk1. A few others attributes need to be changed. The most important one is the PVID, located in CuAt. We will use the value reported as missing by lsvg -p rootvg. Attribute unique_id also need to be changed. You can just change a few characters in the existing string, it just need to be unique in the system. The other attributes to change are connwhere in CuDv and connection in CuPath. Their value represent the LUN ID of the disk. Again, this value is not relevant, it just have to be unique. We can check the current LUN defined by running lscfg on all the disks defined:

# lscfg -vl hdisk*
 hdisk0           U9117.570.65E4B6A-V6-C2-T1-L810000000000  Virtual SCSI Disk Drive
 hdisk2           U9117.570.65E4B6A-V6-C3-T1-L810000000000  Virtual SCSI Disk Drive
 hdisk3           U9117.570.65E4B6A-V6-C3-T1-L820000000000  Virtual SCSI Disk Drive

LUN 81 is used on controller C2 and LUNs 81 and 82 on C3. Let’s choose 85, which for sure will not collide with other devices. The following commands will generate the text files that will be used to cheat the ODM, according to what was just explained:

# mkdir /tmp/cheat
# cd /tmp/cheat
# odmget -q "name=hdisk0" CuAt | sed -e 's/hdisk0/hdisk1/g'
   -e 's/00ce4b6ade6da849/00ce4b6a01292201/'
   -e 's/609SYMMETRIX/719SYMMETRIX/' > hdisk1.CuAt
# odmget -q "name=hdisk0" CuDv | sed -e 's/hdisk0/hdisk1/'
   -e 's/810000000000/850000000000/' > hdisk1.CuDv
# odmget -q "name=hdisk0" CuPath | sed -e 's/hdisk0/hdisk1/'
   -e 's/810000000000/850000000000/' > hdisk1.CuPAth

Let’s look at the generated files:

# cat hdisk1.CuAt
CuAt:
       name = "hdisk1"
       attribute = "unique_id"
       value = "3520200946033223719SYMMETRIX03EMCfcp05VDASD03AIXvscsi"
       type = "R"
       generic = ""
       rep = "n"
       nls_index = 0
CuAt:
       name = "hdisk1"
       attribute = "pvid"
       value = "00ce4b6a012922010000000000000000"
       type = "R"
       generic = "D"
       rep = "s"
       nls_index = 11
# cat hdisk1.CuDv
CuDv:
       name = "hdisk1"
       status = 1
       chgstatus = 2
       ddins = "scsidisk"
       location = ""
       parent = "vscsi0"
       connwhere = "850000000000"
       PdDvLn = "disk/vscsi/vdisk"
# cat hdisk1.CuPath
CuPath:
       name = "hdisk1"
       parent = "vscsi0"
       connection = "850000000000"
       alias = ""
       path_status = 1
       path_id = 0

So, we are ready to insert the data in the ODM:

# odmadd hdisk1.CuAt
# odmadd hdisk1.CuDv
# odmadd hdisk1.CuPath
# lsvg -p rootvg
rootvg:
PV_NAME           PV STATE          TOTAL PPs   FREE PPs    FREE DISTRIBUTION
hdisk0            active            2157        1019        174..00..00..413..432
hdisk1            missing           2157        1019        174..71..00..342..432

The disk is now back in ODM! Now, to remove the disk from the VGDA, we use the reducevg command:

# reducevg rootvg hdisk1
0516-016 ldeletepv: Cannot delete physical volume with allocated
       partitions. Use either migratepv to move the partitions or
       reducevg with the -d option to delete the partitions.
0516-884 reducevg: Unable to remove physical volume hdisk1.

We will use the -d flag to remove the physical partitions associated to each logical volumes and located hdisk1. A few lines have been remove to simplify listing…

# reducevg -d rootvg hdisk1
0516-914 rmlv: Warning, all data belonging to logical volume
       lv01 on physical volume hdisk1 will be destroyed.
rmlv: Do you wish to continue? y(es) n(o)?
y
0516-304 putlvodm: Unable to find device id 00ce4b6a012922010000000000000000 in the
       Device Configuration Database.
0516-896 reducevg: Warning, cannot remove physical volume hdisk1 from
       Device Configuration Database.
# lsvg -l rootvg
rootvg:
LV NAME             TYPE       LPs   PPs   PVs  LV STATE      MOUNT POINT
hd5                 boot       2     2     1    closed/syncd  N/A
hd6                 paging     256   256   1    open/syncd    N/A
hd8                 jfs2log    1     1     1    open/syncd    N/A
hd4                 jfs2       7     7     1    open/syncd    /
hd2                 jfs2       384   384   1    open/syncd    /usr
hd9var              jfs2       64    64    1    open/syncd    /var
hd3                 jfs2       128   128   1    open/syncd    /tmp
hd1                 jfs2       2     2     1    open/syncd    /home
hd10opt             jfs2       32    32    1    open/syncd    /opt
fslv04              jfs2       256   256   1    open/syncd    /usr/sys/inst.images
loglv01             jfslog     1     1     1    closed/syncd  N/A
lv01                jfs        5     5     1    closed/syncd  /mkcd/cd_images
# lsvg -p rootvg
rootvg:
PV_NAME           PV STATE          TOTAL PPs   FREE PPs    FREE DISTRIBUTION
hdisk0            active            2157        1019        174..00..00..413..432

The disk has been deleted from the VGDA. What about ODM?

# lsdev -Cc disk
hdisk0 Available  Virtual SCSI Disk Drive
hdisk1 Available  Virtual SCSI Disk Drive
hdisk2 Available  Virtual SCSI Disk Drive
hdisk3 Available  Virtual SCSI Disk Drive
# rmdev -dl hdisk1
Method error (/etc/methods/ucfgdevice):
       0514-043 Error getting or assigning a minor number.

We probably forgot to cheat one ODM class… Never mind: let’s remove the cheat we added to ODM and see what appends:

# odmdelete -o CuAt -q "name=hdisk1"
2 objects deleted
# lspv
hdisk0          00ce4b6ade6da849                    rootvg          active
hdisk2          00ce4b6a01b09b83                    drakevg         active
hdisk1          none                                None
hdisk3          00ce4b6afd175206                    drakevg         active
# rmdev -dl hdisk1
Method error (/etc/methods/ucfgdevice):
       0514-043 Error getting or assigning a minor number.
# odmdelete -o CuDv -q "name=hdisk1"
1 objects deleted
# lspv
hdisk0          00ce4b6ade6da849                    rootvg          active
hdisk2          00ce4b6a01b09b83                    drakevg         active
hdisk3          00ce4b6afd175206                    drakevg         active
# lspath
Enabled hdisk0 vscsi0
Enabled hdisk2 vscsi0
Enabled hdisk2 vscsi1
Enabled hdisk3 vscsi1
Enabled hdisk3 vscsi0
Unknown hdisk1 vscsi0
# odmdelete -o CuPath -q "name=hdisk1"
1 objects deleted
# lspath
Enabled hdisk0 vscsi0
Enabled hdisk2 vscsi0
Enabled hdisk2 vscsi1
Enabled hdisk3 vscsi1
Enabled hdisk3 vscsi0

That’s it! Use with care.