# Configuring the base size device for tenant data storage

Use this procedure to configure the base size of virtual storage devices for tenants in the application data thin pool. The base size is used each time a tenant device is created. In particular, the first time serviced starts, it creates the base size device and then creates a tenant device from the base size device.

The following Control Center configuration variable is used to specify the base size device:

SERVICED_DM_BASESIZE
Default: 100G
The base size of virtual storage devices for tenants in the application data thin pool, in gigabytes. The units symbol (G) is required. This variable is used when serviced starts for the first time, to set the initial size of tenant devices, and when a backup is restored, to set the size of the restored tenant device.
The base size device is sparse device that occupies at most 1MB of space in the application data thin pool; its size has no immediate practical impact. However, the application data thin pool should have enough space for twice the size of each tenant device it supports, to store both the data itself and snapshots of the data. Since the application data thin pool is an LVM logical volume, its size can be increased at any time. Likewise, the size of a tenant device can be increased, as long as the available space in the thin pool can support the larger tenant device plus snapshots.

Perform these steps:

1. Log in to the master host as root, or as a user with superuser privileges.
2. Identify the size of the thin pool for application data.
The size is required to set an accurate value for the SERVICED_DM_BASESIZE variable.
lvs --options=lv_name,lv_size | grep serviced-pool
3. Edit storage variables in the Control Center configuration file.
1. Open /etc/default/serviced in a text editor.
2. Locate the line for the SERVICED_DM_BASESIZE variable, and then make a copy of the line, immediately below the original.
3. Remove the number sign character (#) from the beginning of the line.
4. Change the value, if necessary.
Replace Fifty-Percent with the value that is less than or equal to 50% of the size of the thin pool for application data. Include the symbol for gigabytes, G:
SERVICED_DM_BASESIZE=Fifty-PercentG
5. Save the file, and then close the editor.
4. Verify the settings.
grep -E '^\b*SERVICED' /etc/default/serviced