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The following documentation lists all documented options for MSE4. Any additional undocumented configuration variables are subject to change, and should only be applied after consulting with Varnish Software’s support services.
These are the different value types used by the configuration keys and their expected value format.
Unquoted unsigned number.
Unquoted floating point number.
true or false.
Quoted string.
Quoted string where the first character has to be a letter.
Quoted string containing an integer number, optionally followed by a unit
like m.
Takes a configuration group. Each key in the group can itself be a child
category group. Keys named as *<property-name>* set properties on
the category.
Category properties:
*memory_weight*
Sets the memory weight of the category
*subdivisions*
Set the number of subdivisions to apply to this category.
*stores*
Set the list of stores belonging to this category.
*store_select*
Specify the algorithm to use when selecting a store from the available stores in this category.
See Categories for more information.
Takes a list of configuration groups, where each group defines a book instance.
Takes a list of configuration groups, where each group defines a store instance.
Ephemeral object memory chunk size
The maximum size of the memory chunks allocated for ephemeral object fragments.
Varylib table size
Size of table chunk used for vary library
Require all file devices
Require that all configured file devices (books and sores) are available when starting the Varnish daemon.
Default number category subdivisions
Category subdivisions used when the MSE4 configuration file does not specify a specific subdivision for the category.
Default store selection algorithm
Default algorithm to use in categories that do not specify a specific store selection algorithm for the category.
Default object category
Default category to assign new objects when VCL does not set a category. The value ‘fail’ will cause object creation failure.
Category definition tree
Category definition tree. See Categories for more information
List of books
List of books defined in this environment.
Book id
Symbolic ID of this book.
Book filename
The full path filename of the book file that will hold persisted object metadata.
Book size
The size of the book in bytes.
Require file devices
Require that this book is available when starting the Varnish daemon.
Ban journal size
The size of the book ban journal in bytes.
Size of the slot journal
Length of journal slot commit lineup
Number of slots to line up for journal commit before new submissions are queued.
Attempt using hugepages for the slot table
If true, an attempt at allocating the slot table using reserved hugepages will be made, with fallback to regular pages.
Mark slot table for use with transparent hugepages
Mark slot table allocation for use with transparent hugepages.
Attempt using hugepages for the quickslot table
If true, an attempt at allocating the quickslot table using reserved hugepages will be made, with fallback to regular pages.
Mark quickslot table for use with transparent hugepages
Mark quickslot table allocation for use with transparent hugepages.
Persisted object Ykey search tree key bits
Number of key bits used in the persisted object Ykey search tree root selection. This setting is closely related to the ykey_slot_bits, and the number of roots in use is two to the power of the sum of the settings. Note that the sum is not allowed to exceed 20.
Persisted object Ykey search tree slot bits
Number of bits from the slot number used in the persisted object Ykey search tree root selection. This setting is closely related to the ykey_key_bits setting, and the number of roots in use is two to power of the sum of the settings. Note that the sum is not allowed to exceed 20.
Engine to use for book writing
Engine to use for asynchronous writing to the book. Valid values are ‘auto’, ‘iouring’ and ‘classic’.
The maximum number of outstanding AIO requests for writing to the slot table.
The maximum number of outstanding AIO requests for writing to the quickslot table.
Batch size to use when evicting objects to free slots
The number of objects to batch up when evicting objects to increase the number of free slots in the book.
The percentage of slots to be kept in reserve
When the number of unused slots goes below this percentage of the total number of available slots in the book, objects will start to be evicted to free up slots.
Apply extra alloc related debug
Apply extra alloc related debug operations. This comes at a cost.
List of stores
List of stores defined in this book.
Store id
Symbolic ID of this store.
Storage file name
The full path filename of the storage file that will hold the persisted objects.
Store size
The size of the store in bytes.
Require file devices
Require that this store is available when starting the Varnish daemon.
Store segment size
The size of the segments the store is divided into and used to track allocations. The actual selected segment size will be subject to rounding internally.
Minimum size of a free chunk to be counted towards the free reserve
See Persisted Caching for a description on how the background task for freeing up space in the store and how reserve_size is interpreted.
The target allocation chunk size for persisted objects
This setting determines the size of the chunks to break down large persisted objects into.
Segment low fill level remap threshold
Fill level threshold below which segments will be considered for remapping available space, making it available again for future allocations.
Fraction of store objects painted as candidates for store purges
This fraction of the objects on the store LRU will be painted as candidates for store purge when there is too little space available for new objects in the cache. The painted objects are all eligeble for purging, and which object is purged is based on the location they occupy in the store so that continous free areas may be created.
Engine to use for store reading and writing
Engine to use for asynchronous reading and writing to and from the store. Valid values are ‘auto’, ‘iouring’ and ‘classic’.
Number of simultaneous AIO requests to schedule on the store
Number of simultaneous AIO requests to schedule on the store.
Number of AIO requests to queue before blocking
Number of AIO requests to queue before blocking.
Produce checksum of store writes
Produce checksum of store writes.
Verify checksum on store reads
Verify checksum on store reads.
Checksum algorithm
Which checksum algorithm to use for the store. Valid values are ‘xxh3’.