# 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_AUTO_UPDATE If set to no, disables the automatic update of file catalogs.
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_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_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_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_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_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 that shall be mountable under /cvmfs.
CVMFS_REPOSITORY_TAG Select a named repository snapshot that should be mounted instead of trunk.
CVMFS_ROOT_HASH Hash of the root file catalog, implies CVMFS_AUTO_UPDATE=no.
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_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.

## Server parameters¶

Parameter Meaning
CVMFS_CREATOR_VERSION The CernVM-FS version that was used to create this repository (do not change manually).
CVMFS_IGNORE_XDIR_HARDLINKS If set to yes, do not abort the publish operation when cross-directory hardlinks are found. Instead automatically break the hardlinks across directories.
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_SPOOL_DIR Location of the upstream spooler scratch directories; the read-only CernVM-FS moint point and copy-on-write storage reside here.
CVMFS_UPSTREAM_STORAGE Upstream spooler description defining the basic upstream storage type and configuration.
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_AUTO_REPAIR_MOUNTPOINT Set to true to enable automatic recovery from bogus server mount states.
CVMFS_UNION_DIR Mount point of the union file system between CernVM-FS and AUFS. 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 is fully supported)
CVMFS_AUFS_WARNING Set to false to silence AUFS kernel deadlock warning.
CVMFS_HASH_ALGORITHM Define which secure hash algorithm should be used by CernVM-FS for CAS objects
(supported are: sha1 and rmd160)
CVMFS_CATALOG_ENTRY_WARN_THRESHOLD Threshold of catalog entry count before triggering a warning message.
CVMFS_USER The user name that owns and manipulates the files inside the repository.
CVMFS_USE_FILE_CHUNKING Allows backend to split big files into small chunks (true | false)
CVMFS_MIN_CHUNK_SIZE Minimal size of a file chunk in bytes