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fs_getserverprefs - Online in the Cloud

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This is the command fs_getserverprefs that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator

PROGRAM:

NAME


fs_getserverprefs - Displays preference ranks for file servers or VL servers

SYNOPSIS


fs getserverprefs [-file <output to named file>]
[-numeric] [-vlservers] [-help]

fs gets [-f <output to named file>] [-n] [-v] [-h]

fs gp [-f <output to named file>] [-n] [-v] [-h]

DESCRIPTION


The fs getserverprefs command displays preference ranks for file server machine interfaces
(file server machines run the fs process) or, if the -vlserver flag is provided, for
Volume Location (VL) Server machines (which run the vlserver process). For file server
machines, the Cache Manager tracks up to 15 interfaces per machine and assigns a separate
rank to each interface. The ranks indicate the order in which the local Cache Manager
attempts to contact the interfaces of machines that are housing a volume when it needs to
fetch data from the volume. For VL Server machines, the ranks indicate the order in which
the Cache Manager attempts to contact a cell's VL Servers when requesting VLDB
information. For both types of rank, lower integer values are more preferred.

The Cache Manager stores ranks in kernel memory. Once set, a rank persists until the
machine reboots, or until the fs setserverprefs command is used to change it.
fs_setserverprefs(1) explains how the Cache Manager sets default ranks, and how to use
that command to change the default values.

Default VL Server ranks range from 10,000 to 10,126. The Cache Manager assigns ranks to
every machine listed in its copy of the /etc/openafs/CellServDB file or found via DNS
AFSDB or SRV records for the cell when it initializes. When the Cache Manager needs to
fetch VLDB information from a cell, it compares the ranks for the VL Server machines
belonging to that cell, and attempts to contact the VL Server with the lowest integer
rank. If the Cache Manager cannot reach the VL Server (because of server process, machine
or network outage), it tries to contact the VL Server with the next lowest integer rank,
and so on. If all of a cell's VL Server machines are unavailable, the Cache Manager cannot
fetch data from the cell.

Default file server ranks range from 5,000 to 40,000, excluding the range used for VL
Servers (10,000 to 10,126); the maximum possible rank is 65,534. When the Cache Manager
needs to fetch data from a volume, it compares the ranks for the interfaces of machines
that house the volume, and attempts to contact the interface that has the lowest integer
rank. If it cannot reach the fileserver process via that interface (because of server
process, machine or network outage), it tries to contact the interface with the next
lowest integer rank, and so on. If it cannot reach any of the interfaces for machines that
house the volume, it cannot fetch data from the volume.

For both file server machines and VL Server machines, it is possible for a machine or
interface in a foreign cell to have the same rank as a machine or interface in the local
cell. This does not present a problem, because the Cache Manager only ever compares ranks
for machines belonging to one cell at a time.

OPTIONS


-file <output file>
Specifies the full pathname of a file to which to write the preference ranks. If the
specified file already exists, the command overwrites its contents. If the pathname is
invalid, the command fails. If this argument is not provided, the preference ranks
appear on the standard output stream.

-numeric
Displays the IP addresses of file server machine interfaces or VL Server machines,
rather than their hostnames. If this argument is not provided, the fs command
interpreter has the IP addresses translated to hostnames such as "fs1.abc.com".

-vlservers
Displays preference ranks for VL Server machines rather than file server machine
interfaces.

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

OUTPUT


The output consists of a separate line for each file server machine interface or VL Server
machine, pairing the machine's hostname or IP address with its rank. The Cache Manager
stores IP addresses in its kernel list of ranks, but the command by default identifies
interfaces by hostname, by calling a translation routine that refers to either the cell's
name service (such as the Domain Name Server) or the local host table. If an IP address
appears in the output, it is because the translation attempt failed. To bypass the
translation step and display IP addresses rather than hostnames, include the -numeric
flag. This can significantly speed the production of output.

By default, the command writes to the standard output stream. Use the -file argument to
write the output to a file instead.

EXAMPLES


The following example displays the local Cache Manager's preference ranks for file server
machines. The local machine belongs to the AFS cell named abc.com, and in this example the
ranks of file server machines in its local cell are lower than the ranks of file server
machines from the foreign cell, "def.com". It is not possible to translate the IP
addresses of two machines on the 138.255 network.

% fs getserverprefs
fs2.abc.com 20007
fs3.abc.com 30002
fs1.abc.com 20011
fs4.abc.com 30010
server1.def.com 40002
138.255.33.34 40000
server6.def.com 40012
138.255.33.37 40005

The following example shows hows the output displays IP addresses when the -numeric flag
is included, and illustrates how network proximity determines default ranks (as described
on the fs setserverprefs reference page). The local machine has IP address 192.12.107.210,
and the two file server machines on its subnetwork have ranks of 20,007 and 20,011. The
two file server machines on a different subnetwork of the local machine's network have
higher ranks, 30,002 and 30,010, whereas the ranks of the remaining machines range from
40,000 to 40,012 because they are in a completely different network.

% fs getserverprefs -numeric
192.12.107.214 20007
192.12.105.99 30002
192.12.107.212 20011
192.12.105.100 30010
138.255.33.41 40002
138.255.33.34 40000
138.255.33.36 40012
138.255.33.37 40005

The example shows how the -vlservers flag displays preference ranks for VL Server
machines:

% fs getserverprefs -vlservers
fs2.abc.com 10052
fs3.abc.com 10113
fs1.abc.com 10005

PRIVILEGE REQUIRED


None

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