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Comment: Published by Scroll Versions from space ML1 and version 9.2

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To understand how to manage the Device and Database Utilization, one must first understand how ClustrixDB allocates disk space. ClustrixDB creates and allocates space in three two different files:

device1 (

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main storage)

Permanent The main device1 storage is used for all database data, undo logs, temporary tables, Binlogsbinlogs, and ClustrixDB system usage. Such data resides in the device1 file. For new installations, the initial allocation size of device1 is configurable when ClustrixDB is installed. It can be extended after installation tables, as well as temporary storage used for query execution. The initial size of the device1 file is auto-detected by the ClustrixDB installer, but can also be configured manually. Post-installation, the device1 file's size can be extended using ALTER CLUSTER RESIZE DEVICES. The To decrease the size of the device1 file on disk cannot easily be decreased, see Decreasing device1 Size.

ClustrixDB expects the device1 file to be the same size on every node. On By default, on database startup, ClustrixDB will automatically attempt to resize the device1 file on each node to match the largest device1 file present in the cluster, providing the global . To disable this feature, set device_auto_resize_to_largest is set to true (default on new installations).

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=false.

Temporary storage is used for sorting and grouping of large query results . When required, temporary information and is stored in the device1-temp file. By default, this is set to 5GB (per node), but it is configurable with the global variable device1. There are two global variables to control temp space usage:

  • device_temporary_space_limit_bytes limits the amount of space usable for temporary storage.
  • device_temporary_space_preallocate_bytes specifies the amount of space that will be pre-allocated for temp space (guaranteed for use by temp).

Setting device_temporary_space_limit_bytes. Increasing this value will take allows additional temp space to be used, but does not guarantee additional space will be available for temp. Increasing these values takes effect immediately, while decreasing it will only take takes effect at after database start. ClustrixDB will attempt to make the device1-temp file the same size on every noderestart. 

Info

Prior to ClustrixDB 9.2, temp space was stored in a separate file called device1-temp, but with v9.2, temp space is now managed within the device1 file.

device1-redo (write-ahead log) 

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The default values for these global variables are optimal for most workloads.

Device Configuration Variables

These variables control the uniformity of device1 size throughout the cluster and the size of the device1-temp space, respectively.

VariableDescriptionDefault

device_auto_resize_to_largest

Automatically resize all (online) devices in the cluster to match the largest device

true

device_temporary_space_limit_bytes

Maximum amount number of bytes allowed to be used for temporary containers.

5368709120

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device_temporary_space_preallocate_bytesThe amount of space that will be pre-allocated for temporary storage5368709120

Database Storage Thresholds

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VariableDescriptionDefault ValueAllowed Values

databasefull_message_interval_s

Database guard rail almost full message interval in seconds.

120

Minimum: 10

Maximum: 600

databasefull_user_warn_percentage

Warn about user queries when space usage surpasses this percentage.

80

Minimum: 50

Maximum: databasefull_user_error_percentage - 1

databasefull_user_error_percentage

Fail user queries when space usage surpasses this percentage.

90

Minimum: databasefull_user_warn_percentage + 1

Maximum: databasefull_system_warn_percentage - 1

databasefull_system_warn_percentage

Warn about system queries when space usage surpasses this percentage.

95

Minimum: databasefull_user_error_percentage + 1

Maximum: databasefull_system_error_percentage - 1

databasefull_system_error_percentage

Fail user queries when space usage surpasses this percentage.

97

Minimum: databasefull_system_warn_percentage + 1

Maximum: >99

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The following alerts are triggered when the corresponding global variable is exceeded. This is evaluated each time ClustrixDB allocates space and any alerts necessary are sent every databasefull_message_interval_s seconds. If multiple alerts are detected, only the most critical will appear. To learn more about ClustrixDB's Alerter, see Database Alerts .

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  • Add nodes to the cluster by Expanding Your Cluster's Capacity - Flex Up.

  • Increase available space on the cluster by:

  • Enlarge the size of the device1 file on all nodes by using ALTER CLUSTER RESIZE DEVICES.

  • Terminate and reschedule long running transactions such as ALTERs, Backups, and long-running transactions. These halt garbage collection and cause the undo log to temporarily grow in size.

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