What is the RRD file format?
An .rrd file is a binary time-series database managed by RRDtool, an open-source tool created by Tobias Oetiker and first released in 1999 as a successor to MRTG (Multi Router Traffic Grapher).
The defining characteristic of the format is that it is fixed in size from the moment of creation. When new data is written into a full archive, the oldest entries are overwritten - the circular buffer mechanism that gives the format its "Round Robin" name. The file size set by rrdcreate never grows or shrinks.
A single .rrd file holds multiple data sources (for example, inbound and outbound traffic counters) and multiple Round Robin Archives (RRAs), each storing data at a different resolution using a different consolidation function - AVERAGE, MAX, MIN, or LAST. One file might simultaneously retain 5-minute averages for one week and hourly averages for one year.
The file begins with the 4-byte magic string RRD\0 (52 52 44 00) followed by a version string such as 0003. The binary layout is platform-native: endianness and floating-point representation vary by CPU architecture, so .rrd files cannot be copied directly between incompatible systems. Cross-platform migration requires rrdtool dump (export to XML) followed by rrdtool restore.
RRDtool is the storage backend for network monitoring platforms including Cacti, Smokeping, and Nagios with performance data add-ons.
Security & safety
RISK: LOWRRD files are binary data stores with no executable content. They may contain sensitive operational metrics (server loads, network traffic) - treat as internal infrastructure data.
Format details
in a nutshell- ERDAS IMAGINE Raster Pyramid - ERDAS IMAGINE (Hexagon Geospatial) uses .rrd as reduced-resolution dataset (pyramid) files for faster GIS raster display - unrelated to RRDtool.
Programs that open RRD files
Windows2 apps
RRDtool for Windows
Open-source rrdtool info file.rrd (inspect), rrdtool fetch file.rrd AVERAGE (export data), rrdtool graph out.png ... (create graphs).
Cacti
Open-source Cacti's web interface displays graphs from its own .rrd files; not designed to open arbitrary .rrd files directly. 
macOS1 app
Linux2 apps
RRDtool
Open-source sudo apt install rrdtool; rrdtool info file.rrd; rrdtool dump file.rrd > file.xml (portable export).
R (rrd package)
Open-source install.packages('rrd'); library(rrd); read_rrd('file.rrd') - returns data as R data frame for analysis. Technical details
deep spec| Magic bytes | 52 52 44 00 ("RRD\0") at offset 0, followed by version string (e.g., "0003") |
| Byte order | Platform-native: little-endian on x86/x64, big-endian on SPARC/PowerPC - not portable across architectures |
| Fixed-size design | File size is immutable after rrdcreate; determined entirely by archive definitions set at creation |
| Circular buffer | New data overwrites the oldest entries when an archive is full (Round Robin principle) |
| Round Robin Archives | Multiple RRAs per file, each with independent time resolution and consolidation function |
| Consolidation functions | AVERAGE, MIN, MAX, LAST - each RRA specifies one function applied when aggregating data points |
| Data sources | Multiple DS per file (e.g., inbound + outbound traffic counters stored in a single .rrd) |
| Cross-platform migration | Use rrdtool dump (XML export) followed by rrdtool restore on the target architecture |
| Integrity | No built-in checksums or data integrity verification in the file format |
| Typical file size | 50 KB-50 MB (fixed at creation; never changes during the file's lifetime) |
| Encoding | Binary; IEEE 754 doubles for data values; platform-native integer sizes |
| Monitoring integrations | Native storage for Cacti, Smokeping, Nagios (performance data), and ntopng |
| Released | 1999 (RRDtool 1.0, by Tobias Oetiker) |
| Latest version | RRDtool 1.8.0 (2022) |
| Open standard | Yes · royalty-free |
| Specification | oss.oetiker.ch |
RRD conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about RRD files.
