Automatically Resizable Partitions

Use Replication Server partitions that automatically grow or shrink according to usage.

An automatically resizable partition consists of separate partition files. With an automatically resizable partition, you need not manually increase the partition size or create a new partition when consumption from storing stable queue messages increases, and you need not manually reduce the partition size to conserve disk space if consumption decreases.

Instead, Replication Server responds immediately and automatically grows by creating a new partition file when consumption reaches 80% of the total capacity of the partition. You can set the individual partition file size according to your requirements, and you can set a limit to the total size of the partition according to the available disk space. Replication Server does not create a new partition file, even if consumption for the entire partition reaches 80% capacity, if Replication Server calculates that a new file exceeds the limit for the total size of the partition.

In addition, Replication Server automatically conserves disk space if consumption of the partition drops, by removing the last partition file that was added in a automatically resizable partition, if the file becomes empty. To improve response time and replication performance in case there are rapid fluctuations in disk consumption, Replication Server delays the shrinking of the partition until the total partition usage without the last partition file is lower than 50%.

Use create auto partition path to:

Create a logical partition path for the partition files that Replication Server automatically creates.
Associate the logical partition path to a physical location with sufficient disk space for the partition files.
Set the size of the partition files that Replication Server automatically creates.
Set the maximum total size for all the partition files in the partition.

create auto partition path logical_name 
on 'physical_path'
with auto expand size = size
max size = max_size

For example, to create the auto_uxp logical partition path on the UNIX device named /usr/user1, with an initial partition file size of 100MB, and automatically add a new 100MB partition file to auto_uxp every time the partition file reaches 80% usage, and limit the total size for all the partition files that Replication Server can create automatically to102,400MB, enter:

create auto partition path  auto_uxp on '/usr/user1' 
with auto expand size=100 max size=102400

You can create multiple automatically resizable partitions but each partition must have a unique physical path or logical name, and sufficient disk space.

Replication Server names the partition files that it automatically creates according to the "logical_name"_"partition_number" format, where partition_number is a ten-digit number that Replication Server generates automatically and increases sequentially from 0000000001 to 2147483647 with each file that Replication Server adds. Replication Server can automatically grow or shrink partitions only with partition files named using this format. All other partitions must be manually managed by Replication Server administrators.

Warning! Do not manually delete files in the partition physical location with names that follow the logical name_partition number format as the partition files may contain data, unless the partition file has not been used by Replication Server. You can use admin disk_space to check if Replication Server is using the partition file. Consult the system administrator or technical support.

To manage automatically resizable partitions, use:

alter auto partition path – to change the sizeof one partition file and the maximum size of a automatically resizable partition
drop auto partition path – to remove an automatically resizable partition from Replication Server
admin auto_part_path – to display information on automatically resizable partitions
admin disk_space – to check if a device is an automatically resizable partition
rs_helppartition – stored procedure to display information on all automatically resizable and manually managed partitions

See the Replication Server Reference Manual for descriptions and examples of all the commands and the stored procedure.

There are several restrictions and guidelines to consider when you create and manage automatically resizable partitions

You must have write permission to the physical path before you can create a automatically resizable partition.
You cannot create a automatically resizable partition on a raw device.
You cannot use the disk_affinity parameter to select a automatically resizable partitions for partition affinity. See Select Disk Partitions for Stable Queues in the Replication Server Administration Guide Volume 2.
You can use drop auto partition path to remove only automatically resizable partitions. You cannot use drop auto partition path to remove partitions created with other commands.
You can use drop partition to manually remove an automatically resizable partition if there is an urgent need to release disk space. Otherwise, use drop auto partition path to manage the removal of automatically resizable partitions to ensure that disk space is released properly.
Replication Server does not immediately remove an automatically resizable partition if you execute drop auto partition path. Instead, once this command marks the affected logical partition path as "drop-pending", Replication Server does not create any new automatically resizable partition file on the path. Replication Server only removes the automatically resizable partition after the partition files on the path have been dropped by Replication Server.
Installation of Replication Server creates an initial partition. The initial partition and any partitions you subsequently create manually constitute the minimal partition size that Replication Server retains even after you remove all automatically resizable partitions. You can remove some of the partitions in the minimal partition size but you must ensure that Replication Server retains some partitions of a sufficient size for replication to continue.