Manpages

NAME

afsd, afsd.fuse - Initializes the Cache Manager and starts related daemons

SYNOPSIS

afsd [-afsdb] [-backuptree]
[-biods <number of bkg I/O daemons (aix vm)>]
[-blocks <1024 byte blocks in cache>]
[-cachedir <cache directory>]
[-chunksize <log(2) of chunk size>]
[-confdir <configuration directory>]
[-daemons <number of daemons to use>]
[-dcache <number of dcache entries>] [-debug]
[-dynroot] [-dynroot-sparse] [-enable_peer_stats]
[-enable_process_stats] [-fakestat] [-fakestat-all]
[-files <files in cache>]
[-files_per_subdir <log(2) of files per dir> ]
[-help] [-logfile <Place to keep the  CM  log>]
[-inumcalc] <method>
[-mem_alloc_sleep] [-memcache]
[-mountdir <mount location>] [-nomount]
[-nosettime]
[-prealloc <number of ’small’ preallocated blocks>]
[-rmtsys] [-rootvol <name of  AFS  root volume>]
[-rxbind] [-rxmaxmtu value for maximum  MTU  ]
[-rxpck value for rx_extraPackets ]
[-settime] [-shutdown]
[-splitcache < RW/RO  ratio>]
[-stat <number of stat entries>] [-verbose]
[-disable-dynamic-vcaches]
[-volumes <number of volume entries>]
[-waitclose] [-rxmaxfrags <max # of fragments>]
[-volume-ttl <vldb cache timeout>]

DESCRIPTION

The afsd command initializes the Cache Manager on an AFS client machine by transferring AFS-related configuration information into kernel memory and starting several daemons. afsd.fuse is an experimental variant that initializes a FUSE-based Cache Manager instead of one based on a kernel module.

The afsd command performs the following actions:

By default, the list of database server machines is transferred into the kernel from the /etc/openafs/CellServDB file. Alternatively, when the -afsdb option is used, the list of database server machines is taken from the DNS SRV or AFSDB records for each cell. After initialization, use the fs newcell command to change the kernel-resident list without having to reboot.

The second field in the /etc/openafs/cacheinfo file is the source for this name. The standard value is /usr/vice/cache. Use the -cachedir argument to override the value in the cacheinfo file.

For a memory cache, the following arguments to the afsd command override the value in the cacheinfo file:

For satisfactory memory cache performance, the specified value must leave enough memory free to accommodate all other processes and commands that can run on the machine. If the value exceeds the amount of memory available, the afsd program exits without initializing the Cache Manager and produces the following message on the standard output stream:

afsd: memCache allocation failure at <number> KB

where <number> is how many kilobytes were allocated just before the failure.

For a disk cache, use the -blocks argument to the afsd command to override the value in the cacheinfo file. The value specified in either way sets an absolute upper limit on cache size; values provided for other arguments (such as -dcache and -chunksize) never result in a larger cache. The afsd program rejects any setting larger than 95% of the partition size, and exits after generating an error message on the standard output stream, because the cache implementation itself requires a small amount of disk space and overfilling the partition can cause the client machine to panic.

To change the size of a disk cache after initialization without rebooting, use the fs setcachesize command; the setting persists until the afsd command runs again or the fs setcachesize command is reissued. The fs setcachesize command does not work for memory caches.

For a disk cache, a chunk is a Vn file and this parameter sets the maximum size to which each one can expand. For a memory cache, each chunk is a collection of contiguous memory blocks. The default for a disk cache is between 256 KB and 1 MB depending on the size of the cache. The default for a memory cache is 8 KB.

To override the default chunk size for either type of cache, use the -chunksize argument to provide an integer to be used as an exponent of two; see " OPTIONS" for details. For a memory cache, if total cache size divided by chunk size leaves a remainder, the afsd program rounds down the number of dcache entries, resulting in a slightly smaller cache.

•

Sets the number of dcache entries allocated in machine memory for storing information about the chunks in the cache.

For a disk cache, the /usr/vice/cache/CacheItems file contains one entry for each Vn file. By default, one half the number of these entries (but not more that 2,000) are duplicated as dcache entries in machine memory for quicker access.

For a memory cache, there is no CacheItems file so all information about cache chunks must be in memory as dcache entries. Thus, there is no default number of dcache entries for a memory cache; instead, the afsd program derives it by dividing the cache size by the chunk size.

To set the number of dcache entries, use the -dcache argument; the specified value can exceed the default limit of 2,000. Using this argument is not recommended for either type of cache. Increasing the number of dcache entries for a disk cache sometimes improves performance (because more entries are retrieved from memory rather than from disk), but only marginally. Using this argument for a memory cache requires the issuer to calculate the cache size by multiplying this value by the chunk size.

In addition to setting cache configuration parameters, the afsd program starts the following daemons. (On most system types, these daemons appear as nameless entries in the output of the UNIX ps command.)

•

One cache-truncation daemon, which flushes the cache when free space is required, by writing cached data and status information to the File Server.

The default number of background daemons is two, enough to service at least five simultaneous users of the machine. To increase the number, use the -daemons argument. A value greater than six is not generally necessary.

•

afsd.fuse is a variant of afsd that, instead of initializing a Cache Manager implemented as a kernel module, initializes a FUSE-based AFS client. FUSE (Filesystem in USErspace) is a Linux-only mechanism for providing a file system through a purely user-space daemon without a kernel module component. afsd.fuse takes all of the same options as afsd.

This command does not use the syntax conventions of the AFS command suites. Provide the command name and all option names in full.

CAUTIONS

Before using the -shutdown parameter, use the standard UNIX umount command to unmount the AFS root directory (by convention, /afs). On Linux, unloading the AFS kernel module and then loading it again before restarting AFS after -shutdown is recommended.

AFS has for years had difficulties with being stopped and restarted without an intervening reboot. While most of these issues have been ironed out, stopping and restarting AFS is not recommended unless necessary and rebooting before restarting AFS is still the safest course of action. This does not apply to Linux; it should be safe to restart the AFS client on Linux without rebooting.

In contrast to many client-server applications, not all communication is initiated by the client. When the AFS client opens a file, it registers a callback with the AFS server. If the file changes, the server notifies the client that the file has changed and that all cached copies should be discarded. In order to enable full functionality on the AFS client, including all command-line utilities, the following UDP ports must be open on an firewalls between the client and the server:

fileserver 7000/udp
cachemanager 7001/udp (OpenAFS client. Arla uses 4711/udp)
ptserver 7002/udp
vlserver 7003/udp
kaserver 7004/udp (not needed with Kerberos v5)
volserver 7005/udp
reserved 7006/udp (for future use)
bosserver 7007/udp

Clients will also need to be able to contact your Kerberos KDC to authenticate. If you are using kaserver and klog, you need to allow inbound and outbound UDP on ports >1024 (probably 1024<port<2048 would suffice depending on the number of simultaneous klogs).

Be sure to set the UDP timeouts on the firewall to be at least twenty minutes for the best callback performance.

afsd.fuse was first introduced in OpenAFS 1.5.74. It is only available if OpenAFS was built with the "--enable-fuse-client" configure switch. It should be considered experimental.

OPTIONS

-afsdb

Enable afsdb support. This will use DNS to lookup the SRV or AFSDB records and use that for the database servers for each cell instead of the values in the CellServDB file. This has the advantage of only needing to update one set of DNS records to reconfigure the AFS clients for a new database server as opposed to touching all of the clients, and also allows one to access a cell without preconfiguring its database servers in CellServDB. The format of SRV records is defined in RFC 5864, and the AFSDB record format is in RFC 1183.

-backuptree

Prefer backup volumes for mountpoints in backup volumes. This option means that the AFS client will prefer to resolve mount points to backup volumes when a parent of the current volume is a backup volume. This is similar to the standard behaviour of preferring read-only volumes over read-write volumes when the parent volume is a read-only volume.

-biods <number of I/O daemons>

Sets the number of VM daemons dedicated to performing I/O operations on a machine running a version of AIX with virtual memory ( VM ) integration. If both this argument and the -daemons argument are omitted, the default is five. If this argument is omitted but the -daemons argument is provided, the number of VM daemons is set to twice the value of the -daemons argument.

-blocks <blocks in cache>

Specifies the number of kilobyte blocks to be made available for caching in the machine’s cache directory (for a disk cache) or memory (for a memory cache), overriding the default defined in the third field of the /etc/openafs/cacheinfo file. For a disk cache, the value cannot exceed 95% of the space available in the cache partition. If using a memory cache, do not combine this argument with the -dcache argument, since doing so can possibly result in a chunk size that is not an exponent of 2.

-cachedir <cache directory>

Names the local disk directory to be used as the cache. This value overrides the default defined in the second field of the /etc/openafs/cacheinfo file.

-chunksize <chunk size>

Sets the size of each cache chunk. The integer provided, which must be from the range 0 to 30, is used as an exponent on the number 2. If not supplied, a default chunksize will be determined based on the cache type and cache size, and will range from 13 (8KB) for memory cache and 18 to 20 (256 KB to 1MB) for disk cache. A value of 0 or less, or greater than 30, sets chunk size to the appropriate default. Values less than 10 (which sets chunk size to a 1 KB ) are not recommended. Combining this argument with the -dcache argument is not recommended because it requires that the issuer calculate the cache size that results.

-chunksize is an important option when tuning for performance. Setting this option to larger values can increase performance when dealing with large files.

-confdir <configuration directory>

Names a directory other than the /etc/openafs directory from which to fetch the cacheinfo, ThisCell, and CellServDB configuration files.

-daemons <number of daemons to use>

Specifies the number of background daemons to run on the machine. These daemons improve efficiency by doing prefetching and background writing of saved data. This value overrides the default of 2, which is adequate for a machine serving up to five users. Values greater than 6 are not generally more effective than 6.

Note: On AIX machines with integrated virtual memory ( VM ), the number of VM daemons is set to twice the value of this argument, if it is provided and the -biods argument is not. If both arguments are omitted, there are five VM daemons.

-dcache <number of dcache entries>

Sets the number of dcache entries in memory, which are used to store information about cache chunks. For a disk cache, this overrides the default, which is 50% of the number of Vn files (cache chunks). For a memory cache, this argument effectively sets the number of cache chunks, but its use is not recommended, because it requires the issuer to calculate the resulting total cache size (derived by multiplying this value by the chunk size). Do not combine this argument with the -blocks argument, since doing so can possibly result in a chunk size that is not an exponent of 2.

-debug

Generates a highly detailed trace of the afsd program’s actions on the standard output stream. The information is useful mostly for debugging purposes.

-dynroot

The standard behaviour of the AFS client without the -dynroot option is to mount the root.afs volume from the default cell on the /afs path. The /afs folder and root.afs volume traditionally shows the folders for ThisCell and other cells as configured by the AFS cell administrator.

The -dynroot option changes this. Using this option, the AFS client does not mount the root.afs volume on /afs. Instead it uses the contents of the CellServDB file to populate the listing of cells in /afs. This is known as a DYNamic ROOT. A cell is not contacted until the path /afs/cellname if accessed. This functions similarly to an automounter. The main advantage of using -dynroot is that the AFS client will start properly even without network access, whereas the client not using -dynroot will freeze upon startup if cannot contact the default cell specified in ThisCell and mount the root.afs volume. Dynamic root mode is also sometimes called travelling mode because it works well for laptops which don’t always have network connectivity.

Two advantages of not using dynroot are that listing /afs will usually be faster because the contents of /afs are limited to what the AFS administrator decides and that symbolic links are traditionally created by the AFS administrator to provide a short name for the cell (i.e. cellname.domain.com is aliased to cellname). However, with dynroot, the local system administrator can limit the default contents of /afs by installing a stripped-down CellServDB file, and if dynroot is in effect, the CellAlias file can be used to provide shortname for common AFS cells which provides equivalent functionality to the most commonly used symbolic links.

When the dynamic root (-dynroot, -dynroot-sparse) and the fake stat (-fakestat, -fakestat-all) modes are in effect, the cache manager provides a special directory named /afs/.:mount which allows access to volumes by volume name or ID. The /afs/.:mount directory appears to be empty, but any name in the form of cell:volume will be resolved as a read-write mount point to the specified volume. For example, the user.jdoe volume in the example.com cell would be accessible at the following path: /afs/.:mount/example.com:user.jdoe. This dynamic mount feature is recommended only for temporary access to a volume. Linux-based cache managers provide this dynamic mount feature even when dynamic root (-dynroot, -dynroot-sparse) is not in effect.

-dynroot-sparse

In addition to operating in the manner described for dynroot above, cells other than the local cell are not shown by default until a lookup occurs. Cell aliases as set in the CellAliases file are shown as normal, although they may appear to be dangling links until traversed.

-enable_peer_stats

Activates the collection of Rx statistics and allocates memory for their storage. For each connection with a specific UDP port on another machine, a separate record is kept for each type of RPC (FetchFile, GetStatus, and so on) sent or received. To display or otherwise access the records, use the Rx Monitoring API.

-enable_process_stats

Activates the collection of Rx statistics and allocates memory for their storage. A separate record is kept for each type of RPC (FetchFile, GetStatus, and so on) sent or received, aggregated over all connections to other machines. To display or otherwise access the records, use the Rx Monitoring API.

-fakestat

Return fake values for stat calls on cross-cell mounts. This option makes an "ls -l" of /afs much faster since each cell isn’t contacted, and this and the -fakestat-all options are useful on Mac OS X so that the Finder program doesn’t try to contact every AFS cell the system knows about.

Note that, for the purposes of -fakestat, local cellular mounts count as "cross-cell" mounts. That is, if the local cell is "localcell", a mount for "localcell:root.cell" will count as a "cross-cell" mount and so stat calls for it will be faked with -fakestat. In practice, local cellular mounts are rare and generally discouraged, so this should not generally make a difference.

-fakestat-all

Return fake values for stat calls on all mounts, not just cross-cell mounts. This and the -fakestat options are useful on Mac OS X so that the Finder program doesn’t hang when browsing AFS directories.

-files <files in cache>

Specifies the number of Vn files to create in the cache directory for a disk cache, overriding the default that is calculated as described in " DESCRIPTION" . Each Vn file accommodates a chunk of data, and can grow to a maximum size of 64 KB by default. Do not combine this argument with the -memcache argument.

-files_per_subdir <files per cache subdirectory>

Limits the number of cache files in each subdirectory of the cache directory. The value of the option should be the base-two log of the number of cache files per cache subdirectory (so 10 for 1024 files, 14 for 16384 files, and so forth).

-help

Prints the online help for this command. All other valid options are ignored.

-logfile <log file location>

This option is obsolete and no longer has any effect.

-inumcalc <method>

Specifies the method used by the Cache Manager to generate inode numbers for files, directories, and symlinks in the AFS filesystem. Valid methods are "compat" and "md5". The default method is "compat".

When the "compat" method is in effect, the Cache Manager generates inode numbers for a given inode by multiplying the AFS volume number by 65536, adding the result to the AFS vnode number, and finally truncating the result to a signed 32 bit integer.

When the "md5" method is in effect, the Cache Manager generates inode numbers for a given inode by calculating the MD5 digest of a combination of the cell number, volume number, and vnode number. The result is truncated to a signed 32 bit integer. The "md5" method is computationally more expensive but greatly reduces the chance for inode number collisions, especially when volumes from multiple cells are mounted within the AFS filesystem.

-mem_alloc_sleep

This option is obsolete and no longer has any effect.

-memcache

Initializes a memory cache rather than a disk cache. Do not combine this flag with the -files argument.

-mountdir <mount location>

Names the local disk directory on which to mount the root of the AFS filespace. This value overrides the default defined in the first field of the /etc/openafs/cacheinfo file. If a value other than the /afs directory is used, the machine cannot access the filespace of cells that do use that value.

-nomount

Do not mount AFS on startup. The afs global mount must be mounted via some other means. This is useful on Mac OS X where /afs is sometimes mounted in /Network/afs like other network file systems.

-nosettime

This option is obsolete and no longer has any effect. The operating system provided time keeping daemons should be used to maintain the system time.

-prealloc <number of preallocated blocks>

Specifies the number of pieces of memory to preallocate for the Cache Manager’s internal use. The default initial value is 400, but the Cache Manager dynamically allocates more memory as it needs it.

-rmtsys

Initializes an additional daemon to execute AFS-specific system calls on behalf of NFS client machines. Use this flag only if the machine is an NFS/AFS translator machine serving users of NFS client machines who execute AFS commands.

-rootvol <name of AFS root volume>

Names the read/write volume corresponding to the root directory for the AFS file tree (which is usually the /afs directory). This value overrides the default of the "root.afs" volume. This option is ignored if -dynroot is given.

-rxbind

Bind the Rx socket (one interface only).

-rxmaxfrags <max # of fragments>

Set a limit for the maximum number of UDP fragments Rx will send per Rx packet, and the maximum number of fragments Rx thinks it can receive when advertising its receive size to peers. Practically speaking, setting this option means that you will not see Rx data packets that are broken into more than N fragments, where N is the value specified for this option. Setting this option to 1 effectively prevents fragmentation, and can be useful when dealing with networking equipment that does not properly handle UDP fragments.

Note that this option just specifies a maximum. The actual number of fragments seen on the wire may be less than what is specified, depending on the configuration of the peer.

-rxmaxmtu <value for maximum MTU >

Set a limit for the largest maximum transfer unit (network packet size) that the AFS client on this machine will be willing to transmit. This switch can be used where an artificial limit on the network precludes packets as large as the discoverable MTU from being transmitted successfully.

-rxpck <value for rx_extraPackets>

Set rx_extraPackets to this value. This sets the number of extra Rx packet structures that are available to handle Rx connections. This value should be increased if the "rxdebug 127.0.0.1 -port 7001 -rxstats" command shows no free Rx packets. Increasing this value may improve OpenAFS client performance in some circumstances.

-settime

This option is obsolete and no longer has any effect. The operating system provided time keeping daemons should be used to maintain the system time.

-shutdown

Shuts down the Cache Manager. Before calling afsd with this option, unmount the AFS file system with umount.

-splitcache < RW/RO Ratio>

This allows the user to set a certain percentage of the AFS cache be reserved for read/write content and the rest to be reserved for read-only content. The ratio should be written as a fraction. For example, "-splitcache 75/25" devotes 75% of your cache space to read/write content and 25% to read-only.

-stat <number of stat entries>

Specifies the number of entries to allocate in the machine’s memory for recording status information about the AFS files in the cache. If this value is not specified, the number of stat entires will be autotuned based on the size of the disk cache.

-verbose

Generates a detailed trace of the afsd program’s actions on the standard output stream.

-volumes <number of volume entries>

Specifies the number of memory structures to allocate for storing volume location information. The default value is 200.

-disable-dynamic-vcaches

By default, dynamic vcache overrides the -stat option by using the value of -stat (or the default) as the initial size of the stat (or vcache) pool and increases the pool dynamically as needed on supported platforms. This flag will disable this new functionality and honor the ’-stat’ setting.

-waitclose

Has no effect on the operation of the Cache Manager. The behavior it affected in previous versions of the Cache Manager, to perform synchronous writes to the File Server, is now the default behavior. To perform asynchronous writes in certain cases, use the fs storebehind command.

-volume-ttl

Specifies the maximum amount of time the Cache Manager will cache volume information retrieved from VL Servers.

By default, the Cache Manager will cache read-only volume information as long as a volume callback is held for that volume. The callback may be held as long as files in the read-only volume are being accessed, with no upper limit. For read/write volumes, by default the Cache Manager will cache volume information forever, until a fileserver returns a volume-level error in response to accessing files in that volume.

Use the -volume-ttl option to specify the maximum amount of time in seconds that volume information will be cached, regardless of connectivity to the fileservers. Lowering this value can make the Cache Manager recover more quickly from certain volume/fileserver errors, but will increase the load on the VL Servers for contacted cells.

A typical value is 7200 seconds (2 hours), which is the same as the default callback duration for read-only volumes. The minimum valid value is 600 seconds (10 minutes).

EXAMPLES

The afsd command is normally included in the machine’s AFS initialization file, rather than typed at the command shell prompt. For most disk caches, the appropriate form is

% /etc/openafs/afsd

The following command is appropriate when enabling a machine to act as an NFS/AFS Translator machine serving more than five users.

% /etc/openafs/afsd -daemons 4 -rmtsys

The following command initializes a memory cache and sets chunk size to 16 KB (2^14).

% /etc/openafs/afsd -memcache -chunksize 14

PRIVILEGE REQUIRED

The issuer must be logged in as the local superuser root.

SEE ALSO

fs_newcell(1), afs_cache(5), CellServDB(5), cacheinfo(5)

RFC 5864 <http://www.ietf.org/rfc/rfc5864.txt>; RFC 1183 <http://www.ietf.org/rfc/rfc1183.txt>;

COPYRIGHT

IBM Corporation 2000. <http://www.ibm.com/>; All Rights Reserved.

This documentation is covered by the IBM Public License Version 1.0. It was converted from HTML to POD by software written by Chas Williams and Russ Allbery, based on work by Alf Wachsmann and Elizabeth Cassell.