NAME
fileserver - Initializes the File Server component of the fs process
SYNOPSIS
fileserver [-auditlog <path to log file>]
[-d <debug level>]
[-p <number of processes>]
[-spare <number of spare blocks>]
[-pctspare <percentage spare>] [-b <buffers>]
[-l <large vnodes>] [-s <small vnodes>]
[-vc <volume cachesize>] [-w <call back wait interval>]
[-cb <number of call backs>] [-banner] [-novbc]
[-implicit <admin mode bits: rlidwka>] [-readonly]
[-hr <number of hours between refreshing the host cps>]
[-busyat <redirect clients when queue > n>]
[-nobusy] [-rxpck <number of rx extra packets>]
[-rxdbg] [-rxdbge] [-rxmaxmtu <bytes>]
[-allow-dotted-principals] [-jumbo] [-nojumbo]
[-rxbind <address to bind the Rx socket to>]
[-vattachpar <number of volume attach threads>]
[-m <min percentage spare in partition>]
[-lock] [-L] [-S] [-k <stack size>]
[-realm <Kerberos realm name>]
[-udpsize <size of socket buffer in bytes>]
[-sendsize <size of send buffer in bytes>]
[-abortthreshold <abort threshold>]
[-enable_peer_stats] [-enable_process_stats] [-help]
DESCRIPTION
The fileserver command initializes the File Server component of the
"fs" process. In the conventional configuration, its binary file is
located in the /usr/lib/openafs directory on a file server machine.
The fileserver command is not normally issued at the command shell
prompt, but rather placed into a database server machine’s
/etc/openafs/BosConfig file with the 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 "root".
The File Server creates the /var/log/openafs/FileLog log file as it
initializes, if the file does not already exist. It does not write a
detailed trace by default, but the -d option may be used to increase
the amount of detail. Use the 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 OPTIONS. By
default the fileserver command 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 -S or -L flag
respectively. The following list describes the parameters and
corresponding argument for which the fileserver command sets default
values, and the table below summarizes the setting for each of the
three machine sizes.
· The maximum number of lightweight processes (LWPs) the File Server
uses to handle requests for data; corresponds to the -p argument.
The File Server always uses a minimum of 32 KB of memory for these
processes.
· The maximum number of directory blocks the File Server caches in
memory; corresponds to the -b argument. Each cached directory block
(buffer) consumes 2,092 bytes of memory.
· The maximum number of large vnodes the File Server caches in memory
for tracking directory elements; corresponds to the -l argument.
Each large vnode consumes 292 bytes of memory.
· The maximum number of small vnodes the File Server caches in memory
for tracking file elements; corresponds to the -s argument. Each
small vnode consumes 100 bytes of memory.
· 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 -vc argument.
· The maximum number of callback structures the File Server caches in
memory; corresponds to the -cb argument. Each callback structure
consumes 16 bytes of memory.
· The maximum number of Rx packets the File Server uses; corresponds
to the -rxpck argument. Each packet consumes 1544 bytes of memory.
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 -S or -L flag).
The amount of memory required for the File Server varies. The
approximate default memory usage is 751 KB when the -S flag is used
(small configuration), 1.1 MB when all defaults are used (medium
configuration), and 1.4 MB when the -L flag is used (large
configuration). If additional memory is available, increasing the value
of the -cb and -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:
· Set the -spare argument to the number of extra kilobytes that the
File Server allows as overage. A value of 0 allows no overage.
· Set the -pctspare argument to the percentage of the volume’s quota
the File Server allows as overage.
By default, the File Server implicitly grants the "a" (administer) and
"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 -implicit argument.
The File Server maintains a host current protection subgroup (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 pts adduser or 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 -hr argument.
The File Server stores volumes in partitions. A partition is a
filesystem or directory on the server machine that is named "/vicepX"
or "/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 "/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.
CAUTIONS
Do not use the -k and -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 -k argument to set the number of LWP threads
has no effect.
Do not specify both the -spare and -pctspare arguments. Doing so causes
the File Server to exit, leaving an error message in the
/var/log/openafs/FileLog file.
Options that are available only on some system types, such as the -m
and -lock options, appear in the output generated by the -help option
only on the relevant system type.
Currently, the maximum size of a volume is 2 terabytes (2^31 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.
OPTIONS
-auditlog <log path>
Set and enable auditing.
-d <debug level>
Sets the detail level for the debugging trace written to the
/var/log/openafs/FileLog file. Provide one of the following values,
each of which produces an increasingly detailed trace: 0, 1, 5, 25,
and 125. The default value of 0 produces only a few messages.
-p <number of processes>
Sets the number of threads 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 OpenAFS Release Notes for the current
release.
-spare <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 0 prevents the volume from ever exceeding its
quota. Do not combine this argument with the -pctspare argument.
-pctspare <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 0 and 99. A value of 0 prevents the volume from ever
exceeding its quota. Do not combine this argument with the -spare
argument.
-b <buffers>
Sets the number of directory buffers. Provide a positive integer.
-l <large vnodes>
Sets the number of large vnodes available in memory for caching
directory elements. Provide a positive integer.
-s <small nodes>
Sets the number of small vnodes available in memory for caching
file elements. Provide a positive integer.
-vc <volume cachesize>
Sets the number of volumes the File Server can cache in memory.
Provide a positive integer.
-w <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.
-cb <number of callbacks>
Sets the number of callbacks the File Server can track. Provide a
positive integer.
-banner
Prints the following banner to /dev/console about every 10 minutes.
File Server is running at I<time>.
-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 vos restore command, for
example). Use of this flag is strongly discouraged.
-implicit <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 ("rlidwka") and auxiliary
permission letters ("ABCDEFGH"), or one of the shorthand notations
for groups of permissions ("all", "none", "read", and "write"). To
review the meaning of the permissions, see the fs setacl reference
page.
-hr <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.
-busyat <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 "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 600.
-rxpck <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.
-rxdbg
Writes a trace of the File Server’s operations on Rx packets to the
file /var/log/openafs/rx_dbg.
-rxdbge
Writes a trace of the File Server’s operations on Rx events (such
as retransmissions) to the file /var/log/openafs/rx_dbg.
-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 disabled this check by starting the server with this
option.
-m <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 0 and 30; the default is 8%. A value of 0 means that
the partition can become completely full, which can have serious
negative consequences.
-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.
-L Sets values for many arguments in a manner suitable for a large
file server machine. Combine this flag with any option except the
-S flag; omit both flags to set values suitable for a medium-sized
file server machine.
-S Sets values for many arguments in a manner suitable for a small
file server machine. Combine this flag with any option except the
-L flag; omit both flags to set values suitable for a medium-sized
file server machine.
-k <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 24.
-realm <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 /etc/openafs/server/ThisCell file.
-udpsize <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.
-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.
-nojumbo
Deprecated; jumbograms are disabled by default.
-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.
-abortthreshold <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.
-help
Prints the online help for this command. All other valid options
are ignored.
EXAMPLES
The following bos create command creates an fs process on the file
server machine "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 fs -type fs \
-cmd "/usr/lib/openafs/fileserver -pctspare 10 \
-L" /usr/lib/openafs/volserver /usr/lib/openafs/salvager
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 "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 noticable 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
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 FileLog log in /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 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.
PRIVILEGE REQUIRED
The issuer must be logged in as the superuser "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 bos
create command.
SEE ALSO
BosConfig(5), FileLog(5), bos_create(8), bos_getlog(8), fs_setacl(1),
salvager(8), volserver(8), vos_examine(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.