mirror of
https://git.openafs.org/openafs.git
synced 2025-01-19 07:20:11 +00:00
6ef9f39335
The NAME heading for man pages can't contain a space in the program side or the man pages won't index with some man implementations.
245 lines
10 KiB
Plaintext
245 lines
10 KiB
Plaintext
=head1 NAME
|
|
|
|
fs_mkmount - Creates a mount point for a volume
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
=for html
|
|
<div class="synopsis">
|
|
|
|
B<fs mkmount> S<<< B<-dir> <I<directory>> >>> S<<< B<-vol> <I<volume name>> >>>
|
|
S<<< [B<-cell> <I<cell name>>] >>> [B<-rw>] [B<-fast>] [B<-help>]
|
|
|
|
B<fs mk> S<<< B<-d> <I<directory>> >>> S<<< B<-v> <I<volume name>> >>>
|
|
S<<< [B<-c> <I<cell name>>] >>> [B<-r>] [B<-f>] [B<-h>]
|
|
|
|
=for html
|
|
</div>
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
The B<fs mkmount> command creates a mount point for the volume named by
|
|
the B<-vol> argument at the location in the AFS file space specified by
|
|
the B<-dir> argument. The mount point looks like a standard directory
|
|
element, and serves as the volume's root directory, but is actually a
|
|
special file system object that refers to an AFS volume. When the Cache
|
|
Manager first encounters a given mount point during pathname traversal, it
|
|
contacts the VL Server to learn which file server machines house the
|
|
indicated volume, then fetches a copy of the volume's root directory from
|
|
the appropriate file server machine.
|
|
|
|
It is possible, although not recommended, to create more than one mount
|
|
point to a volume. The Cache Manager can become confused if a volume is
|
|
mounted in two places along the same path through the filespace.
|
|
|
|
The Cache Manager observes three basic rules as it traverses the AFS
|
|
filespace and encounters mount points:
|
|
|
|
=over 4
|
|
|
|
=item Rule 1: Access Backup and Read-only Volumes When Specified
|
|
|
|
When the Cache Manager encounters a mount point that specifies a volume
|
|
with either a C<.readonly> or a C<.backup> extension, it accesses that
|
|
type of volume only. If a mount point does not have either a C<.backup> or
|
|
C<.readonly> extension, the Cache Manager uses Rules 2 and 3.
|
|
|
|
For example, the Cache Manager never accesses the read/write version of a
|
|
volume if the mount point names the backup version. If the specified
|
|
version is inaccessible, the Cache Manager reports an error.
|
|
|
|
=item Rule 2: Follow the Read-only Path When Possible
|
|
|
|
If a mount point resides in a read-only volume and the volume that it
|
|
references is replicated, the Cache Manager attempts to access a read-only
|
|
copy of the volume; if the referenced volume is not replicated, the Cache
|
|
Manager accesses the read/write copy. The Cache Manager is thus said to
|
|
prefer a I<read-only path> through the filespace, accessing read-only
|
|
volumes when they are available.
|
|
|
|
The Cache Manager starts on the read-only path in the first place because
|
|
it always accesses a read-only copy of the B<root.afs> volume if it
|
|
exists; the volume is mounted at the root of a cell's AFS filespace (named
|
|
F</afs> by convention). That is, if the C<root.afs> volume is replicated,
|
|
the Cache Manager attempts to access a read-only copy of it rather than
|
|
the read/write copy. This rule then keeps the Cache Manager on a read-only
|
|
path as long as each successive volume is replicated. The implication is
|
|
that both the C<root.afs> and C<root.cell> volumes must be replicated for
|
|
the Cache Manager to access replicated volumes mounted below them in the
|
|
AFS filespace. The volumes are conventionally mounted at the F</afs> and
|
|
F</afs/I<cellname>> directories, respectively.
|
|
|
|
=item Rule 3: Once on a Read/write Path, Stay There
|
|
|
|
If a mount point resides in a read/write volume and the volume name does
|
|
not have a C<.readonly> or a C<.backup> extension, the Cache Manager
|
|
attempts to access only the a read/write version of the volume. The access
|
|
attempt fails with an error if the read/write version is inaccessible,
|
|
even if a read-only version is accessible. In this situation the Cache
|
|
Manager is said to be on a I<read/write path> and cannot switch back to
|
|
the read-only path unless mount point explicitly names a volume with a
|
|
C<.readonly> extension. (Cellular mount points are an important exception
|
|
to this rule, as explained in the following discussion.
|
|
|
|
=back
|
|
|
|
There are three types of mount points, each appropriate for a different
|
|
purpose because of the manner in which the Cache Manager interprets them.
|
|
|
|
=over 4
|
|
|
|
=item *
|
|
|
|
When the Cache Manager crosses a I<regular> mount point, it obeys all
|
|
three of the mount point traversal rules previously described. To create a
|
|
regular mount point, include only the required B<-dir> and B<-vol>
|
|
arguments to the B<fs mkmount> command.
|
|
|
|
=item *
|
|
|
|
When the Cache Manager crosses a I<read/write> mount point, it attempts to
|
|
access only the volume version named in the mount point. If the volume
|
|
name is the base (read/write) form, without a C<.readonly> or C<.backup>
|
|
extension, the Cache Manager accesses the read/write version of the
|
|
volume, even if it is replicated. In other words, the Cache Manager
|
|
disregards the second mount point traversal rule when crossing a
|
|
read/write mount point: it switches to the read/write path through the
|
|
filespace.
|
|
|
|
To create a read/write mount point, include the B<-rw> flag on the B<fs
|
|
mkmount> command. It is conventional to create only one read/write mount
|
|
point in a cell's filespace, using it to mount the cell's C<root.cell>
|
|
volume just below the AFS filespace root (by convention,
|
|
F</afs/.I<cellname>>). See the I<IBM AFS Quick Beginnings> for
|
|
instructions and the chapter about volume management in the I<IBM AFS
|
|
Administration Guide> for further discussion.
|
|
|
|
Creating a read/write mount point for a read-only or backup volume is
|
|
acceptable, but unnecessary. The first rule of mount point traversal
|
|
already specifies that the Cache Manager accesses them if the volume name
|
|
in a regular mount point has a C<.readonly> or C<.backup> extension.
|
|
|
|
=item *
|
|
|
|
When the Cache Manager crosses a I<cellular> mount point, it accesses the
|
|
indicated volume in the specified cell, which is normally a foreign
|
|
cell. (If the mount point does not name a cell along with the volume, the
|
|
Cache Manager accesses the volume in the cell where the mount point
|
|
resides.) The Cache Manager disregards the third mount point traversal
|
|
rule when crossing a regular cellular mount point: it accesses a read-only
|
|
version of the volume if it is replicated, even if the volume that houses
|
|
the mount point is read/write. Switching to the read-only path in this way
|
|
is designed to avoid imposing undue load on the file server machines in
|
|
foreign cells.
|
|
|
|
To create a regular cellular mount point, include the B<-cell> argument on
|
|
the B<fs mkmount> command. It is conventional to create cellular mount
|
|
points only at the second level in a cell's filespace, using them to mount
|
|
foreign cells' B<root.cell> volumes just below the AFS filespace root (by
|
|
convention, at F</afs/I<foreign_cellname>>). The mount point enables local
|
|
users to access the foreign cell's filespace, assuming they have the
|
|
necessary permissions on the ACL of the volume's root directory and that
|
|
there is an entry for the foreign cell in each local client machine's
|
|
F</usr/vice/etc/CellServDB> file. In the output of the B<fs lsmount>
|
|
command, the cell name and a colon (C<:>) appear between the initial
|
|
number sign and the volume name in a regular cellular mount point name.
|
|
|
|
=back
|
|
|
|
=head1 OPTIONS
|
|
|
|
=over 4
|
|
|
|
=item B<-dir> <I<directory>>+
|
|
|
|
Names the directory to create as a mount point. The directory must not
|
|
already exist. Relative pathnames are interpreted with respect to the
|
|
current working directory.
|
|
|
|
Specify the read/write path to the directory, to avoid the failure that
|
|
results from attempting to create a new mount point in a read-only
|
|
volume. By convention, the read/write path is indicated by placing a
|
|
period before the cell name at the pathname's second level (for example,
|
|
F</afs/.abc.com>). For further discussion of the concept of read/write and
|
|
read-only paths through the filespace, see L<DESCRIPTION>.
|
|
|
|
=item B<-vol> <I<volume name>>
|
|
|
|
Specifies the name or volume ID number of the volume to mount. If
|
|
appropriate, add the C<.readonly> or C<.backup> extension to the name, or
|
|
specify the appropriate volume ID number.
|
|
|
|
=item B<-cell> <I<cell name>>
|
|
|
|
Names the cell in which the volume resides (creates a cellular mount
|
|
point). Provide the fully qualified domain name, or a shortened form that
|
|
disambiguates it from the other cells listed in the local
|
|
F</usr/vice/etc/CellServDB> file.
|
|
|
|
If this argument is omitted, no cell indicator appears in the mount
|
|
point. When the Cache Manager interprets it, it assumes that the volume
|
|
named in the mount point resides in the same cell as the volume that
|
|
houses the mount point.
|
|
|
|
=item B<-rw>
|
|
|
|
Creates a read/write mount point. Omit this flag to create a regular mount
|
|
point.
|
|
|
|
=item B<-fast>
|
|
|
|
Prevents the Volume Location (VL) Server from checking that the volume has
|
|
a VLDB entry and printing a warning message if it does not. Whether or not
|
|
this flag is included, the File Server creates the mount point even when
|
|
the volume has no VLDB entry.
|
|
|
|
=item B<-help>
|
|
|
|
Prints the online help for this command. All other valid options are
|
|
ignored.
|
|
|
|
=back
|
|
|
|
=head1 EXAMPLES
|
|
|
|
The following command creates a regular mount point, mounting the volume
|
|
C<user.smith> at F</afs/abc.com/usr/smith>:
|
|
|
|
% cd /afs/abc.com/usr
|
|
% fs mkmount -dir smith -vol user.smith
|
|
|
|
The following commands create a read/write mount point and a regular mount
|
|
point for the ABC Corporation cell's C<root.cell> volume in that cell's
|
|
file tree. The second command follows the convention of putting a period
|
|
at the beginning of the read/write mount point's name.
|
|
|
|
% fs mkmount -dir /afs/abc.com -vol root.cell
|
|
% fs mkmount -dir /afs/.abc.com -vol root.cell -rw
|
|
|
|
The following command mounts the State University cell's C<root.cell>
|
|
volume in the ABC Corporation cell's file tree, creating a regular
|
|
cellular mount point called F</afs/stateu.edu>. When a ABC Corporation
|
|
Cache Manager encounters this mount point, it crosses into the State
|
|
University cell on a read-only path.
|
|
|
|
% fs mkmount -dir /afs/stateu.edu -vol root.cell -c stateu.edu
|
|
|
|
=head1 PRIVILEGE REQUIRED
|
|
|
|
The issuer must have the C<i> (insert) and C<a> (administer) permissions
|
|
on the ACL of the directory that is to house the mount point.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<CellServDB(5)>,
|
|
L<fs_lsmount(1)>,
|
|
L<fs_rmmount(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.
|