# CernVM-FS Parameters¶

## Client parameters¶

Parameters recognized in configuration files under /etc/cvmfs:

Parameter Meaning
CVMFS_ALIEN_CACHE If set, use an alien cache at the given location
CVMFS_ALT_ROOT_PATH If set to yes, use alternative root catalog path. Only required for fixed catalogs (tag / hash) under the alternative path.
CVMFS_AUTO_UPDATE If set to no, disables the automatic update of file catalogs.
CVMFS_AUTHZ_HELPER Full path to an authz helper, overwrites the helper hint in the catalog.
CVMFS_AUTHZ_SEARCH_PATH Full path to the directory that contains the authz helpers.
CVMFS_BACKOFF_INIT Seconds for the maximum initial backoff when retrying to download data.
CVMFS_CACHE_BASE Location (directory) of the CernVM-FS cache.
CVMFS_CHECK_PERMISSIONS If set to no, disable checking of file ownership and permissions (open all files).
CVMFS_CLAIM_OWNERSHIP If set to yes, allows CernVM-FS to claim ownership of files and directories.
CVMFS_DEBUGLOG If set, run CernVM-FS in debug mode and write a verbose log the the specified file.
CVMFS_DEFAULT_DOMAIN The default domain will be automatically appended to repository names when given without a domain.
CVMFS_DNS_RETRIES Number of retries when resolving proxy names
CVMFS_DNS_TIMEOUT Timeout in seconds when resolving proxy names
CVMFS_EXTERNAL_FALLBACK_PROXY List of HTTP proxies similar to CVMFS_EXTERNAL_HTTP_PROXY. The fallback proxies are added to the end of the normal proxies, and disable DIRECT connections.
CVMFS_EXTERNAL_HTTP_PROXY Chain of HTTP proxy groups to be used when CernVM-FS is accessing external data
CVMFS_EXTERNAL_TIMEOUT Timeout in seconds for HTTP requests to an external-data server with a proxy server
CVMFS_EXTERNAL_TIMEOUT_DIRECT Timeout in seconds for HTTP requests to an external-data server without a proxy server
CVMFS_EXTERNAL_URL Semicolon-separated chain of webservers serving external data chunks.
CVMFS_FALLBACK_PROXY List of HTTP proxies similar to CVMFS_HTTP_PROXY. The fallback proxies are added to the end of the normal proxies, and disable DIRECT connections.
CVMFS_FOLLOW_REDIRECTS When set to yes, follow up to 4 HTTP redirects in requests.
CVMFS_HIDE_MAGIC_XATTRS If set to yes the client will not expose CernVM-FS specific extended attributes
CVMFS_HOST_RESET_AFTER See CVMFS_PROXY_RESET_AFTER.
CVMFS_HTTP_PROXY Chain of HTTP proxy groups used by CernVM-FS. Necessary. Set to DIRECT if you don’t use proxies.
CVMFS_IGNORE_SIGNATURE When set to yes, don’t verify CernVM-FS file catalog signatures.
CVMFS_INITIAL_GENERATION Initial inode generation. Used for testing.
CVMFS_IPFAMILY_PREFER Which IP protocol to prefer when connecting to proxies. Can be either 4 or 6.
CVMFS_KCACHE_TIMEOUT Timeout for path names and file attributes in the kernel file system buffers.
CVMFS_KEYS_DIR Directory containing *.pub files used as repository signing keys. If set, this parameter has precedence over CVMFS_PUBLIC_KEY.
CVMFS_LOW_SPEED_LIMIT Minimum transfer rate a server or proxy must provide.
CVMFS_MAX_IPADDR_PER_PROXY Limit the number of IP addresses a proxy names resolves into. From all registered addresses, up to the limit are randomly selected.
CVMFS_MAX_RETRIES Maximum number of retries for a given proxy/host combination.
CVMFS_MAX_TTL Maximum file catalog TTL in minutes. Can overwrite the TTL stored in the catalog.
CVMFS_MEMCACHE_SIZE Size of the CernVM-FS meta-data memory cache in Megabyte.
CVMFS_MOUNT_RW Mount CernVM-FS as a read/write file system. Write operations will fail but this option can workaround faulty open() flags.
CVMFS_NFILES Maximum number of open file descriptors that can be used by the CernVM-FS process.
CVMFS_NFS_SOURCE If set to yes, act as a source for the NFS daemon (NFS export).
CVMFS_NFS_SHARED If set a path, used to store the NFS maps in an SQlite database, instead of the usual LevelDB storage in the cache directory.
CVMFS_PAC_URLS Chain of URLs pointing to PAC files with HTTP proxy configuration information.
CVMFS_OOM_SCORE_ADJ Set the Linux kernel’s out-of-memory killer priority for the CernVM-FS client [-1000 - 1000].
CVMFS_PROXY_RESET_AFTER Delay in seconds after which CernVM-FS will retry the primary proxy group in case of a fail-over to another group.
CVMFS_PROXY_TEMPLATE Overwrite the default proxy template in Geo-API calls. Only needed for debugging.
CVMFS_PUBLIC_KEY Colon-separated list of repository signing keys.
CVMFS_QUOTA_LIMIT Soft-limit of the cache in Megabyte.
CVMFS_REPOSITORIES Comma-separated list of fully qualified repository names, used for default list by support tools such as cvmfs-talk.
CVMFS_REPOSITORY_DATE A timestamp in ISO format (e.g. 2007-03-01T13:00:00Z). Selects the repository state as of the given date.
CVMFS_REPOSITORY_TAG Select a named repository snapshot that should be mounted instead of trunk.
CVMFS_CONFIG_REPO_REQUIRED If set to yes, no repository can be mounted unless the config repository is available.
CVMFS_ROOT_HASH Hash of the root file catalog, implies CVMFS_AUTO_UPDATE=no.
CVMFS_SERVER_CACHE_MODE Enable special cache semantics for a client used as a release manager repository base line.
CVMFS_SERVER_URL Semicolon-separated chain of Stratum~1 servers.
CVMFS_SHARED_CACHE If set to no, makes a repository use an exclusive cache.
CVMFS_STRICT_MOUNT If set to yes, mount only repositories that are listed in CVMFS_REPOSITORIES.
CVMFS_SYSLOG_FACILITY If set to a number between 0 and 7, uses the corresponding LOCAL$n$ facility for syslog messages.
CVMFS_SYSLOG_LEVEL If set to 1 or 2, sets the syslog level for CernVM-FS messages to LOG_DEBUG or LOG_INFO respectively.
CVMFS_SYSTEMD_NOKILL If set to yes, modify the command line to @vmfs2 ... in order to act as a systemd lowlevel storage manager.
CVMFS_TIMEOUT Timeout in seconds for HTTP requests with a proxy server.
CVMFS_TIMEOUT_DIRECT Timeout in seconds for HTTP requests without a proxy server.
CVMFS_TRACEFILE If set, enables the tracer and trace file system calls to the given file.
CVMFS_USE_GEOAPI Request order of Stratum 1 servers and fallback proxies via Geo-API.
CVMFS_USER Sets the gid and uid mount options. Don’t touch or overwrite.
CVMFS_USYSLOG All messages that normally are logged to syslog are re-directed to the given file. This file can grow up to 500kB and there is one step of log rotation. Required for $mu$CernVM.
CVMFS_WORKSPACE Set the local directory for storing special files (defaults to the cache directory).

## Server parameters¶

Parameter Meaning
CVMFS_AUFS_WARNING Set to false to silence AUFS kernel deadlock warning.
CVMFS_AUTO_GC Enables the automatic garbage collection on publish and snapshot
CVMFS_AUTO_GC_TIMESPAN Date-threshold for automatic garbage collection
(For example: 3 days ago, 1 week ago, ...)
CVMFS_AUTO_REPAIR_MOUNTPOINT Set to true to enable automatic recovery from bogus server mount states.
CVMFS_AUTO_TAG Creates a generic revision tag for each published revision (if set to true).
CVMFS_AUTO_TAG_TIMESPAN Date-threshold for automatic tags, after which auto tags get removed (For example: 4 days ago)
CVMFS_AUTOCATALOGS Enable/disable automatic catalog management using autocatalogs.
CVMFS_AUTOCATALOGS_MAX_WEIGHT Maximum number of entries in an autocatalog to be considered overflowed. Default value: 100000
CVMFS_AUTOCATALOGS_MIN_WEIGHT Minimum number of entries in an autocatalog to be considered underflowed. Default value: 1000
CVMFS_AVG_CHUNK_SIZE Desired Average size of a file chunk in bytes
CVMFS_CATALOG_ALT_PATHS Enable/disable generation of catalog bootstrapping shortcuts during publishing. (Useful when backend directory /data is not publicly accessible)
CVMFS_COMPRESSION_ALGORITHM Compression algorithm to be used during publishing
(currently either ‘default’ or ‘none’)
CVMFS_CREATOR_VERSION The CernVM-FS version that was used to create this repository (do not change manually).
CVMFS_DONT_CHECK_OVERLAYFS_VERSION Disable checking of OverlayFS version before usage. (see Requirements for a new Repository)
CVMFS_ENFORCE_LIMITS Set to true to cause exceeding *LIMIT variables to be fatal to a publish instead of a warning
CVMFS_EXTERNAL_DATA Set to true to mark repository to contain external data that is served from an external HTTP server
CVMFS_FILE_MBYTE_LIMIT Maximum number of megabytes for a published file, default value: 1024
CVMFS_FORCE_REMOUNT_WARNING Enable/disable warning through wall and grace period before forcefully remounting a CernVM-FS repository on the release managere machine.
CVMFS_GARBAGE_COLLECTION Enables repository garbage collection
(Stratum~0 only | if set to true)
CVMFS_GENERATE_LEGACY_BULK_CHUNKS Set to false to disable generation of whole-file objects for large files. Requires clients >= 2.1.7.
CVMFS_GC_DELETION_LOG Log file path to track all garbage collected objects during sweeping for bookkeeping or debugging
CVMFS_HASH_ALGORITHM Define which secure hash algorithm should be used by CernVM-FS for CAS objects
(supported are: sha1, rmd160 and shake128)
CVMFS_IGNORE_SPECIAL_FILES Set to true to skip special files during publish without aborting.
CVMFS_IGNORE_XDIR_HARDLINKS If set to true, do not abort the publish operation when cross-directory hardlinks are found. Instead automatically break the hardlinks across directories.
CVMFS_INCLUDE_XATTRS Set to true to process extended attributes
CVMFS_MAX_CHUNK_SIZE Maximal size of a file chunk in bytes
CVMFS_MAXIMAL_CONCURRENT_WRITES Maximal number of concurrently processed files during publishing.
CVMFS_MIN_CHUNK_SIZE Minimal size of a file chunk in bytes
CVMFS_NESTED_KCATALOG_LIMIT Maximum thousands of files allowed in nested catalogs, default 500
CVMFS_NUM_WORKERS Maximal number of concurrently downloaded files during a Stratum1 pull operation (Stratum~1 only).
CVMFS_PUBLIC_KEY Path to the public key file of the repository to be replicated. (Stratum 1 only).
CVMFS_REPLICA_ACTIVE Stratum1-only: Set to no to skip this Stratum1 when executing cvmfs_server snapshot -a
CVMFS_REPOSITORY_NAME The fully qualified name of the specific repository.
CVMFS_REPOSITORY_TYPE Defines if the repository is a master copy (stratum0) or a replica (stratum1).
CVMFS_REPOSITORY_TTL The frequency in seconds of client lookups for changes in the repository. Defaults to 4 minutes.
CVMFS_ROOT_KCATALOG_LIMIT Maximum thousands of files allowed in root catalogs, default 200
CVMFS_SPOOL_DIR Location of the upstream spooler scratch directories; the read-only CernVM-FS moint point and copy-on-write storage reside here.
CVMFS_STRATUM0 URL of the master copy (stratum0) of this specific repository.
CVMFS_STRATUM1 URL of the Stratum1 HTTP server for this specific repository.
CVMFS_UNION_DIR Mount point of the union file system for copy-on-write semantics of CernVM-FS. Here, changes to the repository are performed (see CernVM-FS Repository Creation and Updating).
CVMFS_UNION_FS_TYPE Defines the union file system to be used for the repository.
(currently aufs and overlayfs are fully supported)
CVMFS_UPSTREAM_STORAGE Upstream spooler description defining the basic upstream storage type and configuration.
CVMFS_USE_FILE_CHUNKING Allows backend to split big files into small chunks (true | false)
CVMFS_USER The user name that owns and manipulates the files inside the repository.
CVMFS_VIRTUAL_DIR Set to true to enable the hidden, virtual .cvmfs/snapshots directory containing entry points to all named tags.
CVMFS_VOMS_AUTHZ Membership requirement (e.g. VOMS authentication) to be added into the file catalogs

## Tiered Cache Parameters¶

The following parameters are used to configure a tiered cache manager instance.

Parameter Meaning
CVMFS_CACHE_$name_UPPER Name of the upper layer cache instance CVMFS_CACHE_$name_LOWER Name of the lower layer cache instance
CVMFS_CACHE_LOWER_READONLY Set to true to avoid populating the lower layer

## External Cache Plugin Parameters¶

The following parameters are used to configure an external cache plugin as a cache manager instance.

Parameter Meaning
CVMFS_CACHE_$name_CMDLINE If the client should start the plugin, the executable and command line parameters of the plugin, separated by comma. CVMFS_CACHE_$name_LOCATOR The address of the socket used for communication with the plugin.

## In-memory Cache Plugin Parameters¶

The following parameters are interpreted from the configuration file provided to the in-memory cache plugin (see Section Example).

Parameter Meaning
CVMFS_CACHE_PLUGIN_DEBUGLOG If set, run CernVM-FS in debug mode and write a verbose log the the specified file.
CVMFS_CACHE_PLUGIN_LOCATOR The address of the socket used for client communication
CVMFS_CACHE_PLUGIN_SIZE The amount of RAM in megabyte used by the plugin for caching.