Use this documentation with care! It describes
the outdated version 7, which was actively
developed around 2014 and is considered dead by the
This documentation reflects the latest update of the v7-stable branch. It describes the 7.6.8 version, which was never released. As such, it contains some content that does not apply to any released version.
To obtain the doc that properly matches your installed v7 version, obtain the doc set from your distro. Each version of rsyslog contained the version that exactly matches it.
As general advise, it is strongly suggested to upgrade to the current version supported by the rsyslog project. The current version can always be found on the right-hand side info box on the rsyslog web site.
Note that there is only limited rsyslog community support available for the outdated v7 version (officially we do not support it at all, but we usually are able to answer simple questions). If you need to stick with v7, it probably is best to ask your distribution for support.
Type: global configuration directive
This directive specifies the maximum size of the cache for dynamically-generated file names. Selector lines with dynamic files names (‘?’ indicator) support writing to multiple files with a single selector line. This setting specifies how many open file handles should be cached. If, for example, the file name is generated with the hostname in it and you have 100 different hosts, a cache size of 100 would ensure that files are opened once and then stay open. This can be a great way to increase performance. If the cache size is lower than the number of different files, the least recently used one is discarded (and the file closed). The hardcoded maximum is 10,000 - a value that we assume should already be very extreme. Please note that if you expect to run with a very large number of files, you probably need to reconfigure the kernel to support such a large number. In practice, we do NOT recommend to use a cache of more than 1,000 entries. The cache lookup would probably require more time than the open and close operations. The minimum value is 1.
Numbers are always in decimal. Leading zeros should be avoided (in some later version, they may be mis-interpreted as being octal). Multiple directives may be given. They are applied to selector lines based on order of appearance.
$DynaFileCacheSize 100 # a cache of 100 files at most