FS_SETSERVERPREFS(1) AFS Command Reference FS_SETSERVERPREFS(1)NAMEfs_setserverprefs - Sets the preference ranks for file servers or VL
servers
SYNOPSIS
fs setserverprefs [-servers <fileserver names and ranks>+]
[-vlservers <VL server names and ranks>+]
[-file <input from named file>] [-stdin] [-help]
fs sets [-se <fileserver names and ranks>+]
[-vl <VL server names and ranks>+]
[-f <input from named file>] [-st] [-h]
fs sp [-se <fileserver names and ranks>+]
[-vl <VL server names and ranks>+]
[-f <input from named file>] [-st] [-h]
DESCRIPTION
The fs setserverprefs command sets the local Cache Manager's preference
ranks for one or more file server machine interfaces or, if the
-vlserver argument is provided, for Volume Location (VL) Server
machines. For file server machines, the numerical ranks determine the
order in which the Cache Manager attempts to contact the interfaces of
machines that are housing a volume. For VL Server machines, the ranks
determine the order in which the Cache Manager attempts to contact a
cell's VL Servers when requesting VLDB information.
The fs getserverprefs reference page explains how the Cache Manager
uses preference ranks when contacting file server machines or VL Server
machines. The following paragraphs explain how the Cache Manager
calculates default ranks, and how to use this command to change the
defaults.
Calculation of Default Preference Ranks
The Cache Manager stores a preference rank in kernel memory as a paired
IP address and numerical rank. If a file server machine is multihomed,
the Cache Manager assigns a distinct rank to each of the machine's
addresses (up to the number of addresses that the VLDB can store per
machine). Once calculated, a rank persists until the machine reboots,
or until this command is used to change it.
The Cache Manager sets default VL Server preference ranks as it
initializes, randomly assigning a rank from the range 10,000 to 10,126
to each of the machines listed in the local /usr/vice/etc/CellServDB
file. If DNS is used to locate VL Servers, the Cache Manager will
assign a rank to every server configured in an AFSDB or SRV record for
that cell. Currently, the priority and weight information from SRV
records is not used. Machines from different cells can have the same
rank, but this does not present a problem because the Cache Manager
consults only one cell's ranks at a time.
The Cache Manager sets default preference ranks for file server machine
as it fetches volume location information from the VLDB. Each time it
learns about file server machine interfaces for which it has not
already set ranks, it assigns a rank to each interface. If the local
client machine has only one IP address, the Cache Manager compares it
to the server interface's IP address and sets a rank according to the
following algorithm. If the client machine is multihomed, the Cache
Manager applies the algorithm to each of the client machine's addresses
and assigns to the file server machine interface the lowest rank that
results.
· If the local machine is a file server machine, the base rank for
each of its interfaces is 5,000.
· If the file server machine interface is on the same subnetwork as
the client interface, its base rank is 20,000.
· If the file server machine interface is on the same network as the
client interface, or is at the distant end of a point-to-point link
with the client interface, its base rank is 30,000.
· If the file server machine interface is on a different network than
the client interface, or the Cache Manager cannot obtain network
information about it, its base rank is 40,000.
After assigning a base rank to a file server machine interface, the
Cache Manager adds to it a number randomly chosen from the range 0
(zero) to 14. As an example, a file server machine interface in the
same subnetwork as the local machine receives a base rank of 20,000,
but the Cache Manager records the actual rank as an integer between
20,000 and 20,014. This process reduces the number of interfaces that
have exactly the same rank. As with VL Server machine ranks, it is
possible for file server machine interfaces from foreign cells to have
the same rank as interfaces in the local cell, but this does not
present a problem. Only the relative ranks of the interfaces that house
a given volume are relevant, and AFS only supports storage of a volume
in one cell at a time.
Setting Non-default Preference Ranks
Use the fs setserverprefs command to reset an existing preference rank,
or to set the initial rank of a file server machine interface or VL
Server machine for which the Cache Manager has no rank. To make a rank
persist across a reboot of the local machine, place the appropriate fs
setserverprefs command in the machine's AFS initialization file.
Specify each preference rank as a pair of values separated by one or
more spaces:
· The first member of the pair is the fully-qualified hostname (for
example, "fs1.abc.com"), or the IP address in dotted decimal
format, of a file server machine interface or VL Server machine
· The second member of the pair is an integer. The possible ranks
range from 1 through 65535.
As with default ranks, the Cache Manager adds a randomly chosen integer
to a rank specified by this command. For file server machine
interfaces, the integer is from the range 0 (zero) to 14; for VL Server
machines, it is from the range 0 (zero) to 126. For example, if the
administrator assigns a rank of 15,000 to a file server machine
interface, the Cache Manager stores an integer between 15,000 to
15,014.
There are several ways to provide ranks for file server machine
interfaces (but not for VL Server machines):
· On the command line, following the -servers argument.
· In a file named by the -file argument. Place each pair on its own
line in the file. Directing the output from the fs getserverprefs
command to a file automatically generates a file with the proper
format.
· Via the standard input stream, by providing the -stdin flag. This
method enables the issuer to feed in values directly from a program
or script that generates preference ranks by using an algorithm
appropriate to the local cell. The AFS distribution does not
include such programs or scripts.
When setting file server machine preference ranks, it is legal to
combine the -servers, -file, and -stdin options on a single command
line. If different options specify a different rank for the same
interface, the Cache Manager stores and uses the rank assigned with the
-servers argument.
The -vlservers argument is the only way to assign VL Server machine
ranks. It can be combined with one or more of the -servers, -file, and
-stdin options, but the Cache Manager applies the values provided for
those options to file server machine ranks only.
The fs command interpreter does not verify hostnames or IP addresses,
and so assigns preference ranks to invalid machine names or addresses.
The Cache Manager never uses such ranks unless the same incorrect
information is in the VLDB.
OPTIONS-servers <file server names and ranks>+
Specifies one or more file server machine preference ranks. Each
rank pairs the fully-qualified hostname or IP address (in dotted
decimal format) of a file server machine's interface with an
integer rank, separated by one or more spaces; also separate each
pair with one or more spaces. Acceptable values for the rank range
from 1 through 65521; a lower value indicates a greater preference.
Providing ranks outside this range can have unpredictable results.
Providing a value no larger than 65521 guarantees that the rank
does not exceed the maximum possible value of 65,535 even if the
largest random factor (14) is added.
This argument can be combined with the -file argument, -stdin flag,
or both. If more than one of the arguments sets a rank for the same
interface, the rank set by this argument takes precedence. It can
also be combined with the -vlservers argument, but does not
interact with it.
-vlservers <VL server names and ranks>+
Specifies one or more VL Server preference ranks. Each rank pairs
the fully-qualified hostname or IP address (in dotted decimal
format) of a VL Server machine with an integer rank, separated by
one or more spaces; also separate each pair with one or more
spaces. Acceptable values for the rank range from 1 through 65521;
a lower value indicates a greater preference. Providing ranks
outside this range can have unpredictable results. Providing a
value no larger than 65521 guarantees that the rank does not exceed
the maximum possible value of 65,535 even if the largest random
factor (14) is added.
This argument can be combined with the -servers argument, -file
argument, -stdin flag, or any combination of the three, but does
not interact with any of them. They apply only to file server
machine ranks.
-file <input file>
Specifies the full pathname of a file from which to read pairs of
file server machine interfaces and their ranks, using the same
notation and range of values as for the -servers argument. In the
file, place each pair on its own line and separate the two parts of
each pair with one or more spaces.
This argument can be combined with the -servers argument, -stdin
flag, or both. If more than one of the arguments sets a rank for
the same interface, the rank set by the -server argument takes
precedence. It can also be combined with the -vlservers argument,
but does not interact with it.
-stdin
Reads pairs of file server machine interface and integer rank from
the standard input stream. The intended use is to accept input
piped in from a user-defined program or script that generates ranks
in the appropriate format, but it also accepts input typed to the
shell. Format the interface and rank pairs as for the -file
argument. If typing at the shell, type Ctrl-D after the final
newline to complete the input.
This argument can be combined with the -servers argument, the -file
argument, or both. If more than one of the arguments sets a rank
for the same interface, the rank set by the -server argument takes
precedence. It can also be combined with the -vlservers argument,
but does not interact with it.
-help
Prints the online help for this command. All other valid options
are ignored.
EXAMPLES
The following command sets the Cache Manager's preference ranks for the
file server machines named "fs3.abc.com" and "fs4.abc.com", the latter
of which is specified by its IP address, 192.12.105.100. The machines
reside in another subnetwork of the local machine's network, so their
default base rank is 30,000. To increase the Cache Manager's preference
for these machines, the issuer assigns a rank of 25000, to which the
Cache Manager adds an integer in the range from 0 to 15.
# fs setserverprefs -servers fs3.abc.com 25000 192.12.105.100 25000
The following command uses the -servers argument to set the Cache
Manager's preference ranks for the same two file server machines, but
it also uses the -file argument to read a collection of preference
ranks from a file that resides in the local file /etc/fs.prefs:
# fs setserverprefs -servers fs3.abc.com 25000 192.12.105.100 25000 \
-file /etc/fs.prefs
The /etc/fs.prefs file has the following contents and format:
192.12.108.214 7500
192.12.108.212 7500
138.255.33.41 39000
138.255.33.34 39000
128.0.45.36 41000
128.0.45.37 41000
The following command uses the -stdin flag to read preference ranks
from the standard input stream. The ranks are piped to the command from
a program, calc_prefs, which was written by the issuer to calculate
preferences based on values significant to the local cell.
# calc_prefs | fs setserverprefs -stdin
The following command uses the -vlservers argument to set the Cache
Manager's preferences for the VL server machines named "fs1.abc.com",
"fs3.abc.com", and "fs4.abc.com" to base ranks of 1, 11000, and 65521,
respectively:
# fs setserverprefs -vlservers fs1.abc.com 1 fs3.abc.com 11000 \
fs4.abc.com 65521
PRIVILEGE REQUIRED
The issuer must be logged in as the local superuser root.
SEE ALSOfs_getserverprefs(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.
OpenAFS 2013-10-09 FS_SETSERVERPREFS(1)
