Discovery: How to create a new swap partition for the Discovery appliance using tw_disk_utils, and how to remove an unused swap partition

Knowledge Article

Discovery: How to create a new swap partition for the Discovery appliance using tw_disk_utils, and how to remove an unused swap partition
The new swap partition will be created by running a command line similar to "tw_disk_utils --new-swap 24576:/dev/sdd", then some other commands will be used to remove the older swap partition.
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A Discovery appliance has a large disk that only contains a small swap partition. This sometimes happens when the datastore is moved to a larger disk, leaving only the swap partition on the original disk.

Customer wants to allocate a new, smaller disk for the swap partition, so that the large disk can be returned. How can this be done?
 

In the following example, the large disk is /dev/sdb and the customer has allocated a new, smaller disk (/dev/sdd) for the swap partition.

- To create a 24gb swap partition on /dev/sdd, use the following command:

$ tw_disk_utils --new-swap 24576:/dev/sdd


Notes:
1. The disk must be a "new disk" as seen in the Disk Configuration utility, i.e. it has not been formatted or partitioned.
2. If the appliance is a member of a cluster, tideway services must be stopped. This should not be required on a standalone appliance.
3. This command does not "move" the existing partition, it just creates a new swap partition.
4. To add a swap file to an existing disk rather creating a swap partition on a new disk, see KA 000296638: Discovery: How to manually add or remove a swap file on an existing partition. 


- To remove the old swap partition before returning the old disk:


1. Run "swapon -s" to get the partition name of the original swap partition (i.e. /dev/sdb1).

2. As root, execute the following command to disable the swap partition:

$ swapoff /dev/sdb1
 

3. As root, Run the blkid command to determine which UUID corresponds to the old sdb1 swap partition.

For example:

[tideway@myaddm ~]$ blkid | grep sdb1 | grep swap
/dev/sdb1: UUID="db116c8c-d900-4e9b-82ca-23d4895a6041" TYPE="swap" PARTLABEL="primary"...


4. Login as root then make a backup of the /etc/fstab file, e.g:

$ su
# cp /etc/fstab /etc/fstab.bak


5. Browse /etc/fstab to see the UUIDs of the existing swap partitions, for example:

UUID=db116c8c-d900-4e9b-82ca-23d4895a6041 swap  swap    defaults        0 0
UUID=a48f504a-8520-4abb-9787-c60fd69850c7 swap  swap    defaults        0 0

6. Remove the entry associated with this UUID corresponding to sdb1 from /etc/fstab.

7. Reboot the appliance

8. Run these commands and check the output to make sure everything is configured properly:

$ mount
$ df - h
$ swapon -s


If so, the /dev/sdb disk can be removed from the appliance.
BMC Discovery
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BMC Discovery + ITOM On Prem All Versions
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