This article details root causes as well as corrective actions to be taken in situations where an Appian Cloud environment is experiencing high disk usage. In addition, some strategies to optimize and control disk usage in Appian environments are listed. In Appian Cloud environments specifically, the top disk consumers are usually those that are listed below.
Note: Appian Support may open a Support Case to notify you if disk usage in your environment crosses 80%. A member of Appian Support will follow up on the Support Case to discuss the largest consumers of disk on your site and potential remediation steps.
Depending on which component of Appian is causing high disk usage, the steps to remediate the issue will vary.
It is possible that sufficient cleanup of actionable consumers of disk is not possible. In this situation, a disk space increase may be necessary to bring disk usage to healthy levels.
This is especially common for sites with 75 GB of storage. This amount of storage space is the minimum that can be provisioned for an Appian Cloud environment and is meant to be used only as a starting point for customers. Many Appian Cloud environments will experience a workload whose storage requirements exceed 75 GB of disk space, therefore requiring a disk space increase.
Additional storage is hot-deployable, meaning a site restart is not required to add additional disk space.
Note: Once additional disk space has been added to the server, it cannot be removed.
Knowledge Centers are one of the most common causes for high disk usage in Appian Cloud environments. You are responsible for deleting any unnecessary documents in the appropriate knowledge centers. Appian Support is unable to delete documents for you on Cloud sites.
Appian Support can provide a breakdown of the largest Knowledge Centers as requested. If you already have a Support Case for addressing high disk usage in your environment, you can request this breakdown in that Support Case. Otherwise, you can create a new Support Case to request this breakdown.
In order to access and delete the documents in the specified knowledge centers, perform the following:
<APPIAN_URL>/suite/design/
<id>
You may see Appian Support reference KC 0 or KC 7 in a disk breakdown. These are unique Knowledge Centers which are present in every Appian environment.
KC 0 contains system images, import/export logs, and deployment packages. This folder cannot be accessed from the frontend. Deployment packages are automatically deleted after 30 days, and you can modify this retention period in the Appian Administration Console. All other files in this folder are stored indefinitely. Appian Support can manually remove files older than a certain number of days from this folder with your permission. To request this manual cleanup, please update your high disk usage Support Case (if one exists) or open a new Support Case.
KC 7 is the Temporary Documents Knowledge Center. By default, files are kept in this Knowledge Center for 30 days. This retention period can be modified by Appian Support. To request a change to this retention period, please update your high disk usage Support Case (if one exists) or open a new Support Case.
Application logs will naturally accumulate in your environment. Application logs using a high amount of disk is not necessarily a cause for immediate concern. However, if application logs are growing rapidly or if disk space is limited, this may require further attention.
While many application logs roll over or are compressed after a certain number of days, there are no global settings for managing log files. Appian Support can compress application logs older than a certain number of days as necessary. To request cleanup of application logs on your site, please update your high disk usage Support Case (if one exists) or open a new Support Case. Compressed logs will still be available to download via <APPIAN_URL>/suite/logs as a .gz file.
<APPIAN_URL>/suite/logs
If application logs have grown a significant amount in a short time, this can be indicative of a recurring issue in your Appian environment that is repeatedly printing errors in the logs. These errors should be addressed as soon as possible to avoid further increases in disk space.
If you have requested additional loggers to be enabled or existing loggers to be modified, it is important that you let Appian Support know as soon as these loggers can be disabled. Leaving them on can increase the size and disk utilization of the logs and is not recommended for long periods of time. Note that all loggers will be reset to default values upon a site restart.
The amount of disk space that the Appian Cloud Database consumes is directly related to the amount of data being stored in the database.
If MySQL data is using a high amount of disk space, consider reducing the amount of data stored in the cloud database. Alternatively, consider moving the data from the Appian Cloud server to an external database server.
Note: If rows are deleted from the cloud database, disk space may not immediately be freed. This is because the rows are not immediately removed, just marked as "deleted" internally. If you delete data from your cloud database but do not see a drop in disk usage, please reach out to Appian Support via Support Case. Appian Support can review your cloud database and reclaim disk space from deleted rows if necessary.
In addition to the RDBMS data mentioned above, all connections made to your cloud database are audited, and all operations performed on the cloud database are stored in the RDBMS binary logs. By default, the binary logs are purged after four days, and the audit logs are removed after 30 days. However, on compliant sites, the audit logs are kept indefinitely for security purposes.
If either of these types of logs are consuming a significant amount of disk space on your site, consider reducing the amount of activity on your cloud database. Alternatively, feel free to open a Support Case with Appian Support to discuss additional options.
Processes which have been archived are moved out of memory and onto disk. Additionally, the process history for all processes is stored on disk. If archived processes or process history are the top consumers of disk space in your environment, there are a few site properties that can be configured by Appian Support to remediate the issue going forward.
Appian Support requires that you provide a number of days to set as the value for the properties above. Additionally, the properties for auto-deletion of archived processes and process history must be configured to the same number of days. Please be aware that Appian Support will need to schedule a maintenance window to deploy any changes to these properties.
Note: Archived processes are automatically compressed after 7 days by default.
The engines are processes that run in memory, but they frequently write data to disk. The most common culprits of high disk usage related to the engines are engine transactions and KDBs.
Engine transactions are copies of every write transaction that gets applied to the engines. They are used to rebuild the engine in case of an unexpected crash.
Appian Support may refer to engine transactions as Kafka logs, since they are managed by Kafka. However, unlike normal log files, engine transactions cannot be manually deleted. Instead, they automatically roll over whenever the engines checkpoint. By default, the engines will try to checkpoint at least every 22 hours, and the latest three checkpoints are saved by default.
If the engine transactions are taking up a high amount of disk space, try reviewing the processes running on your site. Typically, engine transactions scale with the amount of process activity on a site, but certain design implementations (extremely large process variables or many looping processes) can cause extreme growth of the engine transactions. Reach out to Appian Support via Support Case if you have any questions or suspect that engine transactions are responsible for a significant amount of disk usage on your site.
Whenever the engines checkpoint, they store a snapshot of themselves on disk. This snapshot is referred to as a KDB file. Just like engine transactions, only the past three KDB files are saved by default, and they roll over with each checkpoint.
If the engine KDBs are taking up a high amount of disk space, this means that the engines themselves must be taking up a lot of RAM. Please review KB-2011 on addressing high engine memory usage and try to lower the memory used by the engines. Reducing the memory footprint of the engines will lead to a drop in the size of the KDB files for that engine after the next checkpoint.
Robotic executions on your site will generate many artifacts, including screenshots, execution videos, and execution logs. If robotic executions are responsible for a significant amount of disk usage, please review the Automatic Process Clean-Up options for your robotic tasks. Consider modifying the clean-up properties associated with your robotic tasks to help reduce the amount of disk space taken by their respective artifacts.
RPA logs will naturally accumulate on your site as you use RPA. If you are actively using RPA, please navigate to the RPA Console, select "Settings" on the left-hand sidebar, and select "Maintenance". This will allow you to review, download, and delete RPA logs on your site. You may also reach out to Appian Support to request the compression or deletion of RPA logs.
If you are not using RPA on your site and RPA logs are still taking a noticeable amount of disk space, please reach out to Appian Support.
This article applies to all versions of Appian.
Last Reviewed: April 2026