NAME
fs_checkservers - Displays the status of server machines
SYNOPSIS
fs checkservers [-cell <cell to check>] [-all] [-fast]
[-interval <seconds between probes>] [-help]
fs checks [-c <cell to check>] [-a] [-f]
[-i <seconds between probes>] [-h]
DESCRIPTION
The fs checkservers command reports whether certain AFS server machines
are accessible from the local client machine. The machines belong to
one of two classes, and the Cache Manager maintains a list of them in
kernel memory:
· The database server machines in every cell listed in the local
/etc/openafs/CellServDB file, plus any machines added to the memory
list by the fs newcell command since the last reboot.
· All file server machines the Cache Manager has recently contacted,
and which it probably needs to contact again soon. In most cases,
the Cache Manager holds a callback on a file or volume fetched from
the machine.
If the Cache Manager is unable to contact the vlserver process on a
database server machine or the fileserver process on a file server
machine, it marks the machine as inaccessible. (Actually, if a file
server machine is multihomed, the Cache Manager attempts to contact all
of the machine’s interfaces, and only marks the machine as down if the
fileserver fails to reply via any of them.) The Cache Manager then
periodically (by default, every three minutes) sends a probe to each
marked machine, to see if it is still inaccessible. If a previously
inaccessible machine responds, the Cache Manager marks it as accessible
and no longer sends the periodic probes to it.
The fs checkservers command updates the list of inaccessible machines
by having the Cache Manager probe a specified set of them:
· By default, only machines that are marked inaccessible and belong
to the local cell (the cell listed in the local
/etc/openafs/ThisCell file).
· If the -cell argument is included, only machines that are marked
inaccessible and belong to the specified cell.
· If the -all flag is included, all machines marked inaccessible.
If the -fast flag is included, the Cache Manager does not probe any
machines, but instead reports the results of the most recent previous
probe.
To set the interval between probes rather than produce a list of
inaccessible machines, use the -interval argument. The non-default
setting persists until the machine reboots; to preserve it across
reboots, put the appropriate fs checkservers command in the machine’s
AFS initialization files.
CAUTIONS
The command can take quite a while to complete, if a number of machines
do not respond to the Cache Manager’s probe. The Cache Manager probes
machines sequentially and waits a standard timeout period before
marking the machine as unresponsive, to allow for slow network
communication. To make the command shell prompt return quickly, put the
command in the background. It is harmless to interrupt the command by
typing Ctrl-C or another interrupt signal.
Note that the Cache Manager probes only server machines marked
inaccessible in its memory list. A server machine’s absence from the
output does not necessarily mean that it is functioning, because it
possibly is not included in the memory list at all (if, for example,
the Cache Manager has not contacted it recently). For the same reason,
the output is likely to vary on different client machines.
Unlike most fs commands, the fs checkservers command does not refer to
the AFSCELL environment variable.
OPTIONS
-cell <cell to check>
Names each cell in which to probe server machines marked as
inaccessible. Provide the fully qualified domain name, or a
shortened form that disambiguates it from the other cells listed in
the local /etc/openafs/CellServDB file. Combine this argument with
the -fast flag if desired, but not with the -all flag. Omit both
this argument and the -all flag to probe machines in the local cell
only.
-all
Probes all machines in the Cache Manager’s memory list that are
marked inaccessible. Combine this argument with the -fast flag if
desired, but not with the -cell argument. Omit both this flag and
the -cell argument to probe machines in the local cell only.
-fast
Displays the Cache Manager’s current list of machines that are
inaccessible, rather than sending new probes. The output can as old
as the current setting of the probe interval (by default three
minutes, and maximum ten minutes).
-interval <seconds between probes>
Sets or reports the number of seconds between the Cache Manager’s
probes to machines in the memory list that are marked inaccessible:
· To set the interval, specify a value from the range between 1
and 600 (10 minutes); the default is 180 (three minutes). The
issuer must be logged in as the local superuser "root". The
altered setting persists until again changed with this command,
or until the machine reboots, at which time the setting returns
to the default.
· Provide a value of 0 (zero) to display the current interval
setting. No privilege is required. Do not combine this argument
with any other.
-help
Prints the online help for this command. All other valid options
are ignored.
OUTPUT
If there are no machines marked as inaccessible, or if all of them now
respond to the Cache Manager’s probe, the output is:
All servers are running.
Note that this message does not mean that all server machines in each
relevant cell are running. The output indicates the status of only
those machines that the Cache Manager probes.
If a machine fails to respond to the probe within the timeout period,
the output begins with the string
These servers unavailable due to network or server problems:
and lists the hostname of each machine on its own line. The Cache
Manager stores machine records by Internet address, so the format of
each hostname (uppercase or lowercase letters, or an Internet address
in dotted decimal format) depends on how the local cell’s name service
translates it at the time the command is issued. If a server machine is
multihomed, the output lists only one of its interfaces (usually, the
currently most preferred one).
If the -interval argument is provided with a value between 1 and 600,
there is no output. If the value is 0, the output reports the probe
interval as follows:
The current down server probe interval is <interval> secs
EXAMPLES
The following command displays the Cache Manager’s current list of
unresponsive machines in the local cell, rather than probing them
again. The output indicates that if there were any machines marked
inaccessible, they all responded to the previous probe.
% fs checkservers -fast
All servers are running.
The following example probes machines in the Cache Manager’s memory
list that belong to the "stateu.edu" cell:
% fs checkservers -cell stateu.edu
All servers are running.
The following example probes all server machines in the Cache Manager’s
memory list. It reports that two machines did not respond to the probe.
% fs checkservers -all
These servers unavailable due to network or server problems:
fs1.abc.com SV3.STATE.EDU.
PRIVILEGE REQUIRED
To set the probe interval, the issuer must be logged in as the local
superuser "root". Otherwise, no privilege is required.
SEE ALSO
CellServDB(5), ThisCell(5), fs_newcell(1)
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.