Limits#

All accounts, by default, have a preconfigured set of thresholds, or limits, to manage capacity and prevent abuse of the system.

The following table lists the limits for Cloud Backup.

Table: Limits for Cloud Backup

Name

Description

Maximum number of backup configurations per agent

The number of backup configurations per agent is limited only by the maximum JSON document size for the agent configuration. (The agent configuration contains all of the configuration information specific to an agent.) Currently, the maximum JSON document size is 1 MB for the total document.

Maximum number of exclusions and inclusions per backup configuration

The maximum number of exclusions and inclusions per backup configuration is limited only by the maximum JSON document size for the agent configuration. (The agent configuration contains all of the configuration information specific to an agent.) Currently, the maximum JSON document size is 1 MB for the total document.

Maximum length of file paths in the configuration

The maximum length of file paths in the configuration is limited first by the maximum JSON document size of the agent configuration (see the preceding limit) and then by the operating system (OS) limitations. See the documentation for your OS for the exact maximum size of file paths on your OS.

Maximum backup upload speeds

The maximum upload speed of a backup is currently 2 MB per second but that speed depends on multiple factors including Cloud Files server load, network bandwidth, number of CPUs, noisy neighbors, duplicate blocks, and similar items. These factors can reduce the upload speed of a backup by varying amounts. However, duplicate or existing blocks actually increase the speed because uploads are not necessary for those blocks.

CPU usage limits

During an operation like a backup or restore, CPU usage limits are 95 percent by default.

Simultaneous uploads

Simultaneous uploads are based on available CPUs. If a server has one or two CPUs, the agent uses one CPU for its work. If a server has three or four CPUs, the agent uses two CPUs. If a server has five or six CPUs, the agent uses three CPUs. If the server has more than six CPUs, the agent uses no more than four CPUs.

Disk space limits for the cache drive

The disk space of the cache drive is where the agent stores log and database files, as well as temporary files. Currently, if this drive has less than 100 MB free space, Cloud Backup throttles logging and posts a message to the logs. Currently, the total size of the rollover logs is set to 10 files at 500 MB by default, but you can edit the log4cxx.xml file to change this value on a per-machine basis.

Really Simple Events (RSE) throttling levels

RSE communicates with the agent. RSE throttling levels control the traffic to RSE and are defined based on the state of the agent: Idle—once every 30 seconds, Active—once every 2 seconds, and Realtime— continuous.