Create Local Archive Volume

This section explains how to create a local archive volume.

This procedure is carried out using ConfD.

Procedure

The following examples use ConfD through the command-line tool confd_client, which is available on all database nodes. For more information, see ConfD.

Connect to COS

Connect to EXAClusterOS (COS) using c4 connect -t <DEPLOYMENT>[.<NODE>]/cos. For example:

c4 connect -t 1/cos

In most cases it does not matter on which node you access ConfD. If you do not specify a node, c4 will connect to the first active node in the deployment. The command prompt in COS indicates which node you are connected to: 

[root@n11 ~]#

For more information about how to use c4 connect, see How to use c4.

Create a local archive volume

To create a local archive volume, use the ConfD job st_volume_create and set the parameters described in the following table.

Some parameters values for the new archive volume must match the corresponding values for the data volume. To find out the values used by the data volume, use the ConfD jobs db_info and st_node_list. 

confd_client db_info db_name: MY_DATABASE
config:
  num_active_nodes: 4
...
  owner:
  - 500
  - 500
...
nodes:
  active:
  - n11
  - n12
  - n13
  - n14
...
confd_client st_node_list
'0':
  hdd_free_space:
    disk1: 93.5566 GiB
  hdds:
    name: /dev/nvme2n1
    type: disk1
    ...
    name: /dev/nvme3n1
    type: disk1
    ...
  name: n11
   ...
'1':
  hdd_free_space:
    disk1: 93.5566 GiB
  hdds:
    name: /dev/nvme2n1
    type: disk1
    ...
    name: /dev/nvme3n1
    type: disk1
    ...
  name: n12
    ...
'2':
  hdd_free_space:
    disk1: 93.5566 GiB
  hdds:
    name: /dev/nvme2n1
    type: disk1
    ...
    name: /dev/nvme3n1
    type: disk1
    ...
  name: n13
    ...
 '3':
  hdd_free_space:
    disk1: 93.5566 GiB
  hdds:
    name: /dev/nvme2n1
    type: disk1
    ...
    name: /dev/nvme3n1
    type: disk1
    ...
  name: n14
    ...

Required parameters

Parameter name

 Data type

Value

disk

string

The disk name in Exasol for the storage disk where the data volume resides.

owner

tuple, list The database owner as an integer tuple (user id, group id) or list (user name, user group name).

nodes

list

List of node IDs in the data volume.
num_master_nodes integer

The number of master nodes (active nodes) in the data volume.

     

name

string

A name for the new archive volume.

redundancy

integer

The redundancy level of the archive volume.

size

string

Volume size for the archive volume as a string, with unit (MiB, GiB, or TiB).

The size value depends on the database size and the backup schedule.

partition_size

string, integer

4294967296 for volumes <250 GiB

34359738368 for volumes ≥ 250 GiB and <1TiB

274877906944 for volumes ≥ 1 TiB

shared

boolean

true

type

string

archive

block_size string 512 KiB
stripe_size string 512 KiB

Master nodes

The parameter num_master_nodes defines the number of master nodes that the volume will use. The number of master nodes must match the number of active nodes in the cluster. For example: in a cluster that will have 4 active nodes and 1 reserve node (4+1), the number of master nodes is 4.

In the following example, we create a 1 TiB data volume with the name LocalArchiveVolume1 on the storage disk disk1 with 4 master nodes and redundancy 2. The command returns the volume ID for the new volume (vid: 3).

confd_client st_volume_create name: LocalArchiveVolume1 disk: disk1 type: archive size: "1 TiB" num_master_nodes: 4 nodes: [11, 12, 13, 14] redundancy: 2 partition_size: 274877906944 shared: true, owner: [500,500]
# ConfD returns the volume ID of the new archive volume:
vid: 3

The ConfD job st_volume_create does not necessarily use the specified size, but does internal rounding. To check the actual size of the archive volume after creation to see if it is acceptable, use the ConfD job st_volume_info. If the rounding takes up too much space, contact Support.

Enable optimizations

To enable optimizations for the local archive volume, use the ConfD job st_volume_add_label

confd_client st_volume_add_label vname: LocalArchiveVolume1 label: useinitopt
confd_client st_volume_add_label vname: LocalArchiveVolume1 label: usesearchopt

Verification

To verify the properties of the new local archive volume, use the ConfD job st_volume_info with the volume ID: 

confd_client st_volume_info vid: 3
_sec_name: 'EXAVolume : LocalArchiveVolume1'
...