Removal of Disk Drives That Have Already Been Assigned to an LVM for either an x86 or s390 installed MOI Appliance

Products

• Mainframe Operational Intelligence

Issue/Introduction

The Resolution process documented below using the attached remove-disks-lvm script can be used to remove disk volumes that have already been assigned to a MOI appliance LVM in either the x86 or s390 Linux environments.   There are also manual steps that accomplish the same disk removal if the script does not work correctly.

Environment

Mainframe Operational Intelligence Release : 2.0 

Service Pack:  2.0.*

Component : MFOPIN

Resolution

Due to an internal DASD migration, customer was able to format new DASD volumes for his zLinux MOI appliance and complete the appliance installation. In addition, the customer was able to remove unwanted DASD volumes that had been incorrectly assigned to LVM's using the following process with the attached script.   There are also manual steps documented after the script process below. 

 

Removing disk storage devices from MOI LVMs

Backups are strongly recommended prior to removing storage. If possible, we recommend you take a VM snapshot.

Automated process for removing storage

1. Copy the attached script called remove-disks-lvm_1606795749367.sh to the local filesystem of the MOI machine e.g., into /tmp
2. Make the file executable if necessary

sudo chmod +x remove-disks-lvm_1606795749367.sh

1. Shutdown MOI

4. $ cd /opt/moi
5. $ bin/plex shutdown --bg=wait

1. Execute it as follows from your machine to remove the disks from your LVMs:

$  ./remove-disks-lvm_1606795749367.sh /lvm1 /dev/sdf1 /dev/sdk1

$  ./remove-disks-lvm_1606795749367.sh /lvm2 /dev/sdg1 /dev/sdj1

$  ./remove-disks-lvm_1606795749367.sh /lvm3 /dev/sdh1 /dev/sdi1

where /dev/sdf1, /dev/sdk1,... are the disks to be removed.

1. Start MOI

6. $ cd /opt/moi
7. $ bin/plex startup -d --bg=wait

Manual process for removing storage

The following process can be used to manually remove disks. For example, you want to remove the disk /dev/dasdg1 from the LVM mounted at /lvm1

Mounted at /lvm1 is the following LVM: /dev/lvm1_vg/lvm1_lv where the LVM name is lvm1_lv and the LVM volume group is lvm1_vg.

1. Shutdown MOI

2. $ cd /opt/moi
3. $ bin/plex shutdown --bg=wait

1. Unmount the LVM

5. $ umount /lvm1

1. Check the filesystem

7. $ e2fsck -f /dev/lvm1_vg/lvm1_lv

1. Reduce the size of the filesystem on that LVM by the total size of the disk you are removing plus 10%

9. $ removeSize=$(pvs --noheadings --nosuffix --units m -o pv_size /dev/dasdg1)
10. stores the size of the disk in megabytes to removeSize
11. $ lvmSize=$(lvs --noheadings --nosuffix --units m -o lv_size /dev/lvm1_vg/lvm1_lv)
12. stores the size of the logical volume in megabytes to lvmSize
13. $ finalSize=$(( (${lvmSize%.*} - ${removeSize%.*}) * 9 / 10 ))
14. stores the reduced filesystem size in finalSize
15. $ resize2fs /dev/lvm1_vg/lvm1_lv "${finalSize}"M

1. Reduce the allocated physical extents on that LVM by the physical extents on the disk you are removing plus 1

17. $ extentsToRemove=$(pvs --noheadings -o pv_pe_alloc_count /dev/dasdg1)
18. stores the number of extents to remove to extentsToRemove
19. $ (( extentsToRemove++ ))
20. add one more extent so there is an extent free on the remaining disks, otherwise pvmove will return no free extents
21. $ lvreduce -l -${extentsToRemove} /dev/lvm1_vg/lvm1_lv
22. respond with 'y'
23. reduces the size of the LVM

1. Move the extents on the disk you are removing to the other disks

25. $ pvmove /dev/dasdg1
26. will probably return "No data to move for lvm1_vg" but if not then the data migration may take a while.

1. Remove the disk from the volume group

28. $ vgreduce lvm1_vg /dev/dasdg1

1. Mount the LVM

30. $ mount -a

1. Resize the LVM and filesystem to use the entire volume group

32. lvresize -l +100%free /dev/lvm1_vg/lvm1_lv
33. resize2fs /dev/lvm1_vg/lvm1_lv

1. Start MOI

35. $ cd /opt/moi

$ bin/plex startup -d --bg=wait