=head1 NAME

dafileserver - Initializes the File Server component of the dafs process

=head1 SYNOPSIS

=for html
<div class="synopsis">

B<dafileserver>
    S<<< [B<-auditlog> <I<path to log file>>] >>>
    S<<< [B<-audit-interface> (file | sysvmq)] >>>
    S<<< [B<-d> <I<debug level>>] >>>
    S<<< [B<-p> <I<number of processes>>] >>>
    S<<< [B<-spare> <I<number of spare blocks>>] >>>
    S<<< [B<-pctspare> <I<percentage spare>>] >>>
    S<<< [B<-b> <I<buffers>>] >>>
    S<<< [B<-l> <I<large vnodes>>] >>>
    S<<< [B<-s> <I<small vnodes>>] >>>
    S<<< [B<-vc> <I<volume cachesize>>] >>>
    S<<< [B<-w> <I<call back wait interval>>] >>>
    S<<< [B<-cb> <I<number of call backs>>] >>>
    S<<< [B<-banner>] >>>
    S<<< [B<-novbc>] >>>
    S<<< [B<-implicit> <I<admin mode bits: rlidwka>>] >>>
    S<<< [B<-readonly>] >>>
    S<<< [B<-hr> <I<number of hours between refreshing the host cps>>] >>>
    S<<< [B<-busyat> <I<< redirect clients when queue > n >>>] >>>
    S<<< [B<-nobusy>] >>>
    S<<< [B<-rxpck> <I<number of rx extra packets>>] >>>
    S<<< [B<-rxdbg>] >>>
    S<<< [B<-rxdbge>] >>>
    S<<< [B<-rxmaxmtu> <I<bytes>>] >>>
    S<<< [B<-nojumbo>] >>>
    S<<< [B<-jumbo>] >>>
    S<<< [B<-rxbind>] >>>
    S<<< [B<-allow-dotted-principals>] >>>
    S<<< [B<-L>] >>>
    S<<< [B<-S>] >>>
    S<<< [B<-k> <I<stack size>>] >>>
    S<<< [B<-realm> <I<Kerberos realm name>>] >>>
    S<<< [B<-udpsize> <I<size of socket buffer in bytes>>] >>>
    S<<< [B<-sendsize> <I<size of send buffer in bytes>>] >>>
    S<<< [B<-abortthreshold> <I<abort threshold>>] >>>
    S<<< [B<-enable_peer_stats>] >>>
    S<<< [B<-enable_process_stats>] >>>
    S<<< [B<-syslog> [<I< loglevel >>]] >>>
    S<<< [B<-mrafslogs>] >>>
    S<<< [B<-saneacls>] >>>
    S<<< [B<-help>] >>>
    S<<< [B<-vhandle-setaside> <I<fds reserved for non-cache io>>] >>>
    S<<< [B<-vhandle-max-cachesize> <I<max open files>>] >>>
    S<<< [B<-vhandle-initial-cachesize> <I<fds reserved for non-cache io>>] >>>
    S<<< [B<-vattachpar> <I<number of volume attach threads>>] >>>
    S<<< [B<-m> <I<min percentage spare in partition>>] >>>
    S<<< [B<-lock>] >>>
    S<<< [B<-fs-state-dont-save>] >>>
    S<<< [B<-fs-state-dont-restore>] >>>
    S<<< [B<-fs-state-verify>] (none | save | restore | both)] >>>
    S<<< [B<-vhashsize> <I<log(2) of number of volume hash buckets>>] >>>
    S<<< [B<-vlrudisable>] >>>
    S<<< [B<-vlruthresh> <I<minutes before eligibility for soft detach>>] >>>
    S<<< [B<-vlruinterval> <I<seconds between VLRU scans>>] >>>
    S<<< [B<-vlrumax> <I<max volumes to soft detach in one VLRU scan>>] >>>
    S<<< [B<-unsafe-nosalvage>] >>>

=for html
</div>

=head1 DESCRIPTION

The B<dafileserver> command initializes the File Server component of the
C<dafs> process. In the conventional configuration, its binary file is
located in the F</usr/afs/bin> directory on a file server machine.

The B<dafileserver> command is not normally issued at the command shell
prompt, but rather placed into a database server machine's
F</usr/afs/local/BosConfig> file with the B<bos create> command. If it is
ever issued at the command shell prompt, the issuer must be logged onto a
file server machine as the local superuser C<root>.

The File Server creates the F</usr/afs/logs/FileLog> log file as it
initializes, if the file does not already exist. It does not write a
detailed trace by default, but the B<-d> option may be used to
increase the amount of detail. Use the B<bos getlog> command to
display the contents of the log file.

The command's arguments enable the administrator to control many aspects
of the File Server's performance, as detailed in L<OPTIONS>.  By default
the File Server sets values for many arguments that are suitable
for a medium-sized file server machine. To set values suitable for a small
or large file server machine, use the B<-S> or B<-L> flag
respectively. The following list describes the parameters and
corresponding argument for which the File Server sets default
values, and the table below summarizes the setting for each of the three
machine sizes.

=over 4

=item *

The maximum number of lightweight processes (LWPs) or pthreads 
the File Server uses to handle requests for data; corresponds to the 
B<-p> argument. The File Server always uses a minimum of 32 KB of 
memory for these processes.

=item *

The maximum number of directory blocks the File Server caches in memory;
corresponds to the B<-b> argument. Each cached directory block (buffer)
consumes 2,092 bytes of memory.

=item *

The maximum number of large vnodes the File Server caches in memory for
tracking directory elements; corresponds to the B<-l> argument. Each large
vnode consumes 292 bytes of memory.

=item *

The maximum number of small vnodes the File Server caches in memory for
tracking file elements; corresponds to the B<-s> argument.  Each small
vnode consumes 100 bytes of memory.

=item *

The maximum volume cache size, which determines how many volumes the File
Server can cache in memory before having to retrieve data from disk;
corresponds to the B<-vc> argument.

=item *

The maximum number of callback structures the File Server caches in
memory; corresponds to the B<-cb> argument. Each callback structure
consumes 16 bytes of memory.

=item *

The maximum number of Rx packets the File Server uses; corresponds to the
B<-rxpck> argument. Each packet consumes 1544 bytes of memory.

=back

The default values are:

  Parameter (Argument)               Small (-S)     Medium   Large (-L)
  ---------------------------------------------------------------------
  Number of LWPs (-p)                        6           9          128
  Number of cached dir blocks (-b)          70          90          120
  Number of cached large vnodes (-l)       200         400          600
  Number of cached small vnodes (-s)       200         400          600
  Maximum volume cache size (-vc)          200         400          600
  Number of callbacks (-cb)             20,000      60,000       64,000
  Number of Rx packets (-rxpck)            100         150          200

To override any of the values, provide the indicated argument (which can
be combined with the B<-S> or B<-L> flag).

The amount of memory required for the File Server varies. The approximate
default memory usage is 751 KB when the B<-S> flag is used (small
configuration), 1.1 MB when all defaults are used (medium configuration),
and 1.4 MB when the B<-L> flag is used (large configuration). If
additional memory is available, increasing the value of the B<-cb> and
B<-vc> arguments can improve File Server performance most directly.

By default, the File Server allows a volume to exceed its quota by 1 MB
when an application is writing data to an existing file in a volume that
is full. The File Server still does not allow users to create new files in
a full volume. To change the default, use one of the following arguments:

=over 4

=item *

Set the B<-spare> argument to the number of extra kilobytes that the File
Server allows as overage. A value of C<0> allows no overage.

=item *

Set the B<-pctspare> argument to the percentage of the volume's quota the
File Server allows as overage.

=back

By default, the File Server implicitly grants the C<a> (administer) and
C<l> (lookup) permissions to system:administrators on the access control
list (ACL) of every directory in the volumes stored on its file server
machine. In other words, the group's members can exercise those two
permissions even when an entry for the group does not appear on an ACL. To
change the set of default permissions, use the B<-implicit> argument.

The File Server maintains a I<host current protection subgroup> (I<host
CPS>) for each client machine from which it has received a data access
request. Like the CPS for a user, a host CPS lists all of the Protection
Database groups to which the machine belongs, and the File Server compares
the host CPS to a directory's ACL to determine in what manner users on the
machine are authorized to access the directory's contents. When the B<pts
adduser> or B<pts removeuser> command is used to change the groups to
which a machine belongs, the File Server must recompute the machine's host
CPS in order to notice the change. By default, the File Server contacts
the Protection Server every two hours to recompute host CPSs, implying
that it can take that long for changed group memberships to become
effective. To change this frequency, use the B<-hr> argument.

The File Server stores volumes in partitions. A partition is a
filesystem or directory on the server machine that is named C</vicepX>
or C</vicepXX> where XX is "a" through "z" or "aa" though "iv". Up to
255 partitions are allowed. The File Server expects that the /vicepXX
directories are each on a dedicated filesystem. The File Server will
only use a /vicepXX if it's a mountpoint for another filesystem,
unless the file C</vicepXX/AlwaysAttach> exists. The data in the
partition is a special format that can only be access using OpenAFS
commands or an OpenAFS client.

The File Server generates the following message when a partition is nearly
full:

   No space left on device

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

=head1 CAUTIONS

There are two strategies the File Server can use for attaching AFS volumes
at startup and handling volume salvages.  The traditional method assumes
all volumes are salvaged before the File Server starts and attaches all
volumes at start before serving files.  The newer demand-attach method
attaches volumes only on demand, salvaging them at that time as needed,
and detaches volumes that are not in use.  A demand-attach File Server can
also save state to disk for faster restarts. The B<dafileserver> implements
the demand-attach method, while B<fileserver> uses the traditional method.

The choice of traditional or demand-attach File Server changes the
required setup in F<BosConfig>. When changing from a traditional File
Server to demand-attach or vice versa, you will need to stop and remove
the C<fs> or C<dafs> node in F<BosConfig> and create a new node of the
appropriate type. See L<bos_create(8)> for more information.

Do not use the B<-k> and B<-w> arguments, which are intended for use
by the OpenAFS developers only. Changing them from their default
values can result in unpredictable File Server behavior.  In any case,
on many operating systems the File Server uses native threads rather
than the LWP threads, so using the B<-k> argument to set the number of
LWP threads has no effect.

Do not specify both the B<-spare> and B<-pctspare> arguments. Doing so
causes the File Server to exit, leaving an error message in the
F</usr/afs/logs/FileLog> file.

Options that are available only on some system types, such as the B<-m>
and B<-lock> options, appear in the output generated by the B<-help>
option only on the relevant system type.

Currently, the maximum size of a volume quota is 2 terabytes (2^41 bytes)
and the maximum size of a /vicepX partition on a fileserver is 2^64
kilobytes. The maximum partition size in releases 1.4.7 and earlier is
2 terabytes (2^31 bytes). The maximum partition size for 1.5.x
releases 1.5.34 and earlier is 2 terabytes as well.

The maximum number of directory entries is 64,000 if all of the entries
have names that are 15 octets or less in length. A name that is 15 octets
long requires the use of only one block in the directory. Additional
sequential blocks are required to store entries with names that are longer
than 15 octets. Each additional block provides an additional length of 32
octets for the name of the entry. Note that if file names use an encoding
like UTF-8, a single character may be encoded into multiple octets.

In real world use, the maximum number of objects in an AFS directory
is usually between 16,000 and 25,000, depending on the average name
length.

=head1 OPTIONS

=over 4

=item B<-auditlog> <I<log path>>

Turns on audit logging, and sets the path for the audit log.  The audit
log records information about RPC calls, including the name of the RPC
call, the host that submitted the call, the authenticated entity (user)
that issued the call, the parameters for the call, and if the call
succeeded or failed.

=item B<-audit-interface> (file | sysvmq)

Specifies what audit interface to use. The C<file> interface writes audit
messages to the file passed to B<-auditlog>. The C<sysvmq> interface
writes audit messages to a SYSV message (see L<msgget(2)> and
L<msgrcv(2)>). The message queue the C<sysvmq> interface writes to has the
key C<ftok(path, 1)>, where C<path> is the path specified in the
B<-auditlog> option.

Defaults to C<file>.

=item B<-d> <I<debug level>>

Sets the detail level for the debugging trace written to the
F</usr/afs/logs/FileLog> file. Provide one of the following values, each
of which produces an increasingly detailed trace: C<0>, C<1>, C<5>, C<25>,
and C<125>. The default value of C<0> produces only a few messages.

=item B<-p> <I<number of processes>>

Sets the number of threads (or LWPs) to run. Provide a positive integer. 
The File Server creates and uses five threads for special purposes, 
in addition to the number specified (but if this argument specifies 
the maximum possible number, the File Server automatically uses five 
of the threads for its own purposes).

The maximum number of threads can differ in each release of OpenAFS.
Consult the I<OpenAFS Release Notes> for the current release.

=item B<-spare> <I<number of spare blocks>>

Specifies the number of additional kilobytes an application can store in a
volume after the quota is exceeded. Provide a positive integer; a value of
C<0> prevents the volume from ever exceeding its quota. Do not combine
this argument with the B<-pctspare> argument.

=item B<-pctspare> <I<percentage spare>>

Specifies the amount by which the File Server allows a volume to exceed
its quota, as a percentage of the quota. Provide an integer between C<0>
and C<99>. A value of C<0> prevents the volume from ever exceeding its
quota. Do not combine this argument with the B<-spare> argument.

=item B<-b> <I<buffers>>

Sets the number of directory buffers. Provide a positive integer.

=item B<-l> <I<large vnodes>>

Sets the number of large vnodes available in memory for caching directory
elements. Provide a positive integer.

=item B<-s> <I<small nodes>>

Sets the number of small vnodes available in memory for caching file
elements. Provide a positive integer.

=item B<-vc> <I<volume cachesize>>

Sets the number of volumes the File Server can cache in memory.  Provide a
positive integer.

=item B<-w> <I<call back wait interval>>

Sets the interval at which the daemon spawned by the File Server performs
its maintenance tasks. Do not use this argument; changing the default
value can cause unpredictable behavior.

=item B<-cb> <I<number of callbacks>>

Sets the number of callbacks the File Server can track. Provide a positive
integer.

=item B<-banner>

Prints the following banner to F</dev/console> about every 10 minutes.

   File Server is running at I<time>.

=item B<-novbc>

Prevents the File Server from breaking the callbacks that Cache Managers
hold on a volume that the File Server is reattaching after the volume was
offline (as a result of the B<vos restore> command, for example). Use of
this flag is strongly discouraged.

=item B<-implicit> <I<admin mode bits>>

Defines the set of permissions granted by default to the
system:administrators group on the ACL of every directory in a volume
stored on the file server machine. Provide one or more of the standard
permission letters (C<rlidwka>) and auxiliary permission letters
(C<ABCDEFGH>), or one of the shorthand notations for groups of permissions
(C<all>, C<none>, C<read>, and C<write>). To review the meaning of the
permissions, see the B<fs setacl> reference page.

=item B<-readonly>

Don't allow writes to this fileserver.

=item B<-hr> <I<number of hours between refreshing the host cps>>

Specifies how often the File Server refreshes its knowledge of the
machines that belong to protection groups (refreshes the host CPSs for
machines). The File Server must update this information to enable users
from machines recently added to protection groups to access data for which
those machines now have the necessary ACL permissions.

=item B<-busyat> <I<< redirect clients when queue > n >>>

Defines the number of incoming RPCs that can be waiting for a response
from the File Server before the File Server returns the error code
C<VBUSY> to the Cache Manager that sent the latest RPC. In response, the
Cache Manager retransmits the RPC after a delay. This argument prevents
the accumulation of so many waiting RPCs that the File Server can never
process them all. Provide a positive integer.  The default value is
C<600>.

=item B<-rxpck> <I<number of rx extra packets>>

Controls the number of Rx packets the File Server uses to store data for
incoming RPCs that it is currently handling, that are waiting for a
response, and for replies that are not yet complete. Provide a positive
integer.

=item B<-rxdbg>

Writes a trace of the File Server's operations on Rx packets to the file
F</usr/afs/logs/rx_dbg>.

=item B<-rxdbge>

Writes a trace of the File Server's operations on Rx events (such as
retransmissions) to the file F</usr/afs/logs/rx_dbg>.

=item B<-rxmaxmtu> <I<bytes>>

Defines the maximum size of an MTU.  The value must be between the
minimum and maximum packet data sizes for Rx.

=item B<-jumbo>

Allows the server to send and receive jumbograms. A jumbogram is
a large-size packet composed of 2 to 4 normal Rx data packets that share
the same header. The fileserver does not use jumbograms by default, as some
routers are not capable of properly breaking the jumbogram into smaller
packets and reassembling them.

=item B<-nojumbo>

Deprecated; jumbograms are disabled by default.

=item B<-rxbind>

Force the fileserver to only bind to one IP address.

=item B<-allow-dotted-principals>

By default, the RXKAD security layer will disallow access by Kerberos
principals with a dot in the first component of their name. This is to avoid
the confusion where principals user/admin and user.admin are both mapped to the
user.admin PTS entry. Sites whose Kerberos realms don't have these collisions 
between principal names may disable this check by starting the server
with this option.

=item B<-L>

Sets values for many arguments in a manner suitable for a large file
server machine. Combine this flag with any option except the B<-S> flag;
omit both flags to set values suitable for a medium-sized file server
machine.

=item B<-S>

Sets values for many arguments in a manner suitable for a small file
server machine. Combine this flag with any option except the B<-L> flag;
omit both flags to set values suitable for a medium-sized file server
machine.

=item B<-k> <I<stack size>>

Sets the LWP stack size in units of 1 kilobyte. Do not use this argument,
and in particular do not specify a value less than the default of C<24>.

=item B<-realm> <I<Kerberos realm name>>

Defines the Kerberos realm name for the File Server to use. If this
argument is not provided, it uses the realm name corresponding to the cell
listed in the local F</usr/afs/etc/ThisCell> file.

=item B<-udpsize> <I<size of socket buffer in bytes>>

Sets the size of the UDP buffer, which is 64 KB by default. Provide a
positive integer, preferably larger than the default.

=item B<-sendsize> <I<size of send buffer in bytes>>

Sets the size of the send buffer, which is 16384 bytes by default.

=item B<-abortthreshold> <I<abort threshold>>

Sets the abort threshold, which is triggered when an AFS client sends
a number of FetchStatus requests in a row and all of them fail due to
access control or some other error. When the abort threshold is
reached, the file server starts to slow down the responses to the
problem client in order to reduce the load on the file server.

The throttling behaviour can cause issues especially for some versions
of the Windows OpenAFS client. When using Windows Explorer to navigate
the AFS directory tree, directories with only "look" access for the
current user may load more slowly because of the throttling. This is
because the Windows OpenAFS client sends FetchStatus calls one at a
time instead of in bulk like the Unix Open AFS client.

Setting the threshold to 0 disables the throttling behavior. This
option is available in OpenAFS versions 1.4.1 and later.

=item B<-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.

=item B<-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.

=item B<-syslog [<loglevel>]

Use syslog instead of the normal logging location for the fileserver
process.  If provided, log messages are at <loglevel> instead of the
default LOG_USER.

=item B<-mrafslogs>

Use MR-AFS (Multi-Resident) style logging.  This option is deprecated.

=item B<-saneacls>

Offer the SANEACLS capability for the fileserver.  This option is
currently unimplemented.

=item B<-help>

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

=item B<-vhandle-setaside> <I<fds reserved for non-cache io>>

Number of file handles set aside for I/O not in the cache. Defaults to 128.

=item B<-vhandle-max-cachesize> <I<max open files>>

Maximum number of available file handles.

=item B<-vhandle-initial-cachesize> <I<initial open file cache>>

Number of file handles set aside for I/O in the cache. Defaults to 128.

=item B<-vattachpar> <I<number of volume attach threads>>

The number of threads assigned to attach and detach volumes.  The default
is 1.  Warning: many of the I/O parallelism features of Demand-Attach
Fileserver are turned off when the number of volume attach threads is only
1.

This option is only meaningful for a file server built with pthreads
support.

=item B<-m> <I<min percentage spare in partition>>

Specifies the percentage of each AFS server partition that the AIX version
of the File Server creates as a reserve. Specify an integer value between
C<0> and C<30>; the default is 8%. A value of C<0> means that the
partition can become completely full, which can have serious negative
consequences.  This option is not supported on platforms other than AIX.

=item B<-lock>

Prevents any portion of the fileserver binary from being paged (swapped)
out of memory on a file server machine running the IRIX operating system.
This option is not supported on platforms other than IRIX.

=item B<-fs-state-dont-save>

When present, fileserver state will not be saved during shutdown.  Default
is to save state.

=item B<-fs-state-dont-restore>

When present, fileserver state will not be restored during startup.
Default is to restore state on startup.

=item B<-fs-state-verify> (none | save | restore | both)

This argument controls the behavior of the state verification mechanism.
A value of C<none> turns off all verification.  A value of C<save> only
performs the verification steps prior to saving state to disk.  A value
of C<restore> only performs the verification steps after restoring state
from disk.  A value of C<both> performs all verifications steps both
prior to save and following a restore.

The default is C<both>.

=item B<-vhashsize <I<size>>

The log(2) number of of volume hash buckets.  Default is 8 (i.e., by
default, there are 2^8 = 256 volume hash buckets). The minimum that can
be specified is 6 (64 hash buckets). In OpenAFS 1.5.77 and earlier, the
maximum that can be specified is 14 (16384 buckets). After 1.5.77, the
maximum that can be specified is 28 (268435456 buckets).

=item B<-vlruthresh <I<minutes>>

The number of minutes of inactivity before a volume is eligible for soft
detachment.  Default is 120 minutes.

=item B<-vlruinterval <I<seconds>>

The number of seconds between VLRU candidate queue scan.  The default is
120 seconds.

=item B<-vlrumax <I<positive integer>>

The maximum number of volumes which can be soft detached in a single pass
of the scanner.  Default is 8 volumes.

=item B<-unsafe-nosalvage>

This option causes the fileserver to bypass the normal safety check when
attaching volumes that checks the inUse field in the volume header. With
this option, volumes that were in use at the time of an unclean shutdown
will not be salvaged immediately the next time they are accessed, and thus
risk (possibly silent and/or irrevocable) corruption. Volumes will still
be salvaged when an internal inconsistency is detected or other cases
where a salvage would normally occur.

Due to the increased risk of data corruption, the use of this flag is
strongly discouraged. Only use it if you really know what you are doing.

=back

=head1 EXAMPLES

The following B<bos create> command creates a dafs process on
the file server machine C<fs2.abc.com> that uses the large configuration
size, and allows volumes to exceed their quota by 10%. Type the command on
a single line:

   % bos create -server fs2.abc.com -instance dafs -type dafs \
                -cmd "/usr/afs/bin/dafileserver -pctspare 10 -L" \
                /usr/afs/bin/davolserver \
                /usr/afs/bin/salvageserver \
                /usr/afs/bin/dasalvager

=head1 TROUBLESHOOTING

Sending process signals to the File Server Process can change its
behavior in the following ways:

  Process          Signal       OS     Result
  ---------------------------------------------------------------------

  File Server      XCPU        Unix    Prints a list of client IP
                                       Addresses.

  File Server      USR2      Windows   Prints a list of client IP
                                       Addresses.

  File Server      POLL        HPUX    Prints a list of client IP
                                       Addresses.

  Any server       TSTP        Any     Increases Debug level by a power
                                       of 5 -- 1,5,25,125, etc.
                                       This has the same effect as the
                                       -d XXX command-line option.

  Any Server       HUP         Any     Resets Debug level to 0

  File Server      TERM        Any     Run minor instrumentation over
                                       the list of descriptors.

  Other Servers    TERM        Any     Causes the process to quit.

  File Server      QUIT        Any     Causes the File Server to Quit.
                                       Bos Server knows this.

The basic metric of whether an AFS file server is doing well is the number
of connections waiting for a thread,
which can be found by running the following command:

   % rxdebug <server> | grep waiting_for | wc -l

Each line returned by C<rxdebug> that contains the text "waiting_for"
represents a connection that's waiting for a file server thread.

If the blocked connection count is ever above 0, the server is having
problems replying to clients in a timely fashion.  If it gets above 10,
roughly, there will be noticeable slowness by the user.  The total number of
connections is a mostly irrelevant number that goes essentially
monotonically for as long as the server has been running and then goes back
down to zero when it's restarted.

The most common cause of blocked connections rising on a server is some
process somewhere performing an abnormal number of accesses to that server
and its volumes.  If multiple servers have a blocked connection count, the
most likely explanation is that there is a volume replicated between those
servers that is absorbing an abnormally high access rate.

To get an access count on all the volumes on a server, run:

   % vos listvol <server> -long

and save the output in a file.  The results will look like a bunch of B<vos
examine> output for each volume on the server.  Look for lines like:

   40065 accesses in the past day (i.e., vnode references)

and look for volumes with an abnormally high number of accesses.  Anything
over 10,000 is fairly high, but some volumes like root.cell and other
volumes close to the root of the cell will have that many hits routinely.
Anything over 100,000 is generally abnormally high.  The count resets about
once a day.

Another approach that can be used to narrow the possibilities for a
replicated volume, when multiple servers are having trouble, is to find all
replicated volumes for that server.  Run:

   % vos listvldb -server <server>

where <server> is one of the servers having problems to refresh the VLDB
cache, and then run:

   % vos listvldb -server <server> -part <partition>

to get a list of all volumes on that server and partition, including every
other server with replicas.

Once the volume causing the problem has been identified, the best way to
deal with the problem is to move that volume to another server with a low
load or to stop any runaway programs that are accessing that volume
unnecessarily.  Often the volume will be enough information to tell what's
going on.

If you still need additional information about who's hitting that server,
sometimes you can guess at that information from the failed callbacks in the
F<FileLog> log in F</var/log/afs> on the server, or from the output of:

   % /usr/afsws/etc/rxdebug <server> -rxstats

but the best way is to turn on debugging output from the file server.
(Warning: This generates a lot of output into FileLog on the AFS server.)
To do this, log on to the AFS server, find the PID of the fileserver
process, and do:

    kill -TSTP <pid>

where <pid> is the PID of the file server process.  This will raise the
debugging level so that you'll start seeing what people are actually doing
on the server.  You can do this up to three more times to get even more
output if needed.  To reset the debugging level back to normal, use (The
following command will NOT terminate the file server):

    kill -HUP <pid>

The debugging setting on the File Server should be reset back to normal when
debugging is no longer needed.  Otherwise, the AFS server may well fill its
disks with debugging output.

The lines of the debugging output that are most useful for debugging load
problems are:

    SAFS_FetchStatus,  Fid = 2003828163.77154.82248, Host 171.64.15.76
    SRXAFS_FetchData, Fid = 2003828163.77154.82248

(The example above is partly truncated to highlight the interesting
information).  The Fid identifies the volume and inode within the volume;
the volume is the first long number.  So, for example, this was:

   % vos examine 2003828163
   pubsw.matlab61                   2003828163 RW    1040060 K  On-line
       afssvr5.Stanford.EDU /vicepa 
       RWrite 2003828163 ROnly 2003828164 Backup 2003828165 
       MaxQuota    3000000 K 
       Creation    Mon Aug  6 16:40:55 2001
       Last Update Tue Jul 30 19:00:25 2002
       86181 accesses in the past day (i.e., vnode references)

       RWrite: 2003828163    ROnly: 2003828164    Backup: 2003828165
       number of sites -> 3
          server afssvr5.Stanford.EDU partition /vicepa RW Site 
          server afssvr11.Stanford.EDU partition /vicepd RO Site 
          server afssvr5.Stanford.EDU partition /vicepa RO Site 

and from the Host information one can tell what system is accessing that
volume.

Note that the output of L<vos_examine(1)> also includes the access count, so
once the problem has been identified, vos examine can be used to see if the
access count is still increasing.  Also remember that you can run vos
examine on the read-only replica (e.g., pubsw.matlab61.readonly) to see the
access counts on the read-only replica on all of the servers that it's
located on.

=head1 PRIVILEGE REQUIRED

The issuer must be logged in as the superuser C<root> on a file server
machine to issue the command at a command shell prompt.  It is conventional
instead to create and start the process by issuing the B<bos create>
command.

=head1 SEE ALSO

L<BosConfig(5)>,
L<FileLog(5)>,
L<bos_create(8)>,
L<bos_getlog(8)>,
L<fs_setacl(1)>,
L<msgget(2)>,
L<msgrcv(2)>,
L<salvager(8)>,
L<volserver(8)>,
L<vos_examine(1)>

=head1 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.

