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Index for Section 8 |
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Alphabetical listing for V |
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vdump(8)
NAME
vdump - performs full and incremental backups on mounted filesets
SYNOPSIS
/sbin/vdump -h
/sbin/vdump -V
/sbin/vdump -w
/sbin/vdump [-0..9] [-CDNUquv] [-F num_buffers] [-T tape_num] [-b size] [-f
device] [-x num_blocks] fileset
OPTIONS
-h Displays usage help for vdump.
-V Displays the current version of vdump.
-w Displays the filesets that have not been backed up within one week.
-0..9
Specifies the backup level. The value 0 for this option causes the
entire fileset to be backed up to the storage device. The default
backup level is 9.
-C Compresses the data as it is backed up, which minimizes the saveset
size.
-D Performs a level 0 backup on the specified subdirectory. This option
overrides any backup level specification in the command. If this option
is specified, the AdvFS user and group quota files and the fileset
quotas are not backed up.
-N Does not rewind the storage device, when it is a tape.
-U Does not unload the storage device, when it is a tape.
-q Displays only error messages; does not display information messages.
-u Updates the /etc/vdumpdates file with a timestamp entry from the
beginning of the backup.
-v Displays the names of the files being backed up.
-F num_buffers
Specifies the number of in-memory buffers to use. The valid range is 2
through 64 buffers; the default is 8 buffers. The size of the in-
memory buffers is determined by the value of the -b option.
-T tape_num
Specifies the starting number for the first tape. The default number is
1. The tape number is used only to prompt the operator to load another
tape in the drive.
-b size
Specifies the number of 1024-byte blocks per record in the saveset.
The valid range is 1 through 64 blocks; the default is 60 blocks per
record. The value of this option also determines the size of the in-
memory buffers.
-f device
Specifies the destination of the saveset, which can be a device, a
file, or, when the - (dash) character is specified, standard output.
-x num_blocks
Specifies an "exclusive or" (XOR) operation each time the blocks
specified by num_blocks are written to the saveset. The XOR operation
is performed on the blocks and the results written to the saveset as an
XOR block that immediately follows the blocks. Subsequently, you can
use the vrestore command to recover one of the blocks in the group
should a read error occur. The valid range is 1 through 32 blocks; the
default is 8 blocks. Using the -x option creates larger savesets and
increases the amount of time required to back up a file system, but
offers additional protection from saveset errors.
OPERANDS
fileset
Specifies the full path name of a mounted AdvFS fileset to be backed
up. Alternatively, specifies a mounted NFS or UFS file system. When
used with the -D option, specifies a subdirectory.
DESCRIPTION
The vdump command backs up files from a single mounted fileset or clone
fileset to a local storage device. The vdump command is the backup facility
for the AdvFS file system. However, the vdump command is file-system
independent, and you can use it to back up other file systems, such as UFS
and NFS.
The vdump command backs up all files in the specified fileset that are new
or changed since a certain date and produces a saveset on the storage
device. The date is determined by comparing the specified backup level to
previous backup levels recorded in the /etc/vdumpdates file. The default
storage device is /dev/rmt0h. You can specify an alternate storage device
by using the -f option.
The vdump command performs either an incremental backup, level 9 to 1, or a
full backup, level 0, depending on the desired level of backup and the
level of previous backups recorded in the /etc/vdumpdates file.
Note that an incremental dump only captures the files that have changed,
ignoring all others. This means that if you perform a level 0 dump and a
later incremental dump, deleted files are not marked as gone (deleted). If
you then do a complete restore with a level 0 saveset and incremental
backups, the deleted files will be restored. You must then delete these
files individually.
The vdump command backs up all files that are new or have changed since the
latest backup date of all backup levels that are lower than the backup
level being performed. If a backup level that is lower than the specified
level does not exist, the vdump command initiates a level 0 backup. A level
0 backup backs up all the files in the fileset.
After the backup operation is complete, you can use the vrestore -t command
to verify that the backup contains the files you wanted to save. The
vrestore -t command lists the name and size of each file in the saveset
without restoring them.
When you specify the -C option, the vdump command backs up the files with
compression. You cannot specify the compression ratio, it is determined by
the contents of the dump.
When you specify the -u option, the vdump command enters a time-stamp entry
of that fileset and its backup level into the /etc/vdumpdates file.
If a file-system entry with a specific backup level does not already exist
in the /etc/vdumpdates file, the vdump command appends the file with a new
vdump record; otherwise, the vdump command overwrites the existing record,
changing the backup date to reflect the most current backup session. This
occurs after all files in the named fileset have been successfully backed
up.
The vdump and vrestore commands save and restore AdvFS sparse files.
However, sparse files that have been striped are still handled in the
fashion of releases earlier than DIGITAL UNIX Version 4.0D: they are
allocated disk space and filled with zeros.
You do not have to be the root user to use the vdump command. The AdvFS
quota files and fileset quotas in the fileset are included in a saveset
when you are the root user and a full fileset is saved. AdvFS quota files
and fileset quotas can only be backed up for locally-mounted filesets.
Under normal usage, the vdump command uses a small amount of additional
space on the storage device, typically less than 1 percent, when a fileset
is backed up. If the -x option is used, the amount of additional space used
to back up the fileset increases.
RESTRICTIONS
The vdump command does not back up filesets that are not mounted.
Filesets backed up by using the vdump command must be restored by using the
vrestore command. The vdump command is not interchangeable with the dump
command. Similarly, the vrestore command is not interchangeable with the
restore command.
The vrestore command in versions earlier than DIGITAL UNIX Version 4.0
cannot be used to restore savesets produced by the vdump command in DIGITAL
UNIX Version 4.0 or higher systems.
The /etc/vdumpdates file is written in ASCII and consists of a single
record per line. You must be the root user to update this file or to
change any record field.
Caution
If you edit the /etc/vdumpdates file, be certain that all records
follow the correct format. An incorrectly formatted record in this
file may make the file inaccessible for updates or reads.
EXAMPLES
1. A typical /etc/vdumpdates file includes entries like the following,
defining the fileset name, last backup level, and date:
dmn2#set2 8 wed Mar 3 07:40:35 1993
dmn2#set2 9 Thu Mar 4 07:20:42 1993
dmn2#set2 3 Fri Mar 5 07:47:37 1993
dmn2#set2 7 Thu Mar 4 08:23:05 1993
/dev/rz0g 0 Mon Mar 8 12:11:42 1993
In this example, dmn2#set2 represents an AdvFS fileset; /dev/rz0g
represents a UFS file system. If you perform a level 8 backup of the
dmn2#set2, using this /etc/vdumpdates file, you can expect the
following results:
·
The vdump command ignores the /dev/rz0g entry, because it does not
match the specified fileset, dmn2#set2.
·
The vdump command ignores the level 8 and 9 entries, because these
entries are equal to or higher than the level 8 backup you
requested. This leaves only the level 3 and 7 entries.
·
Of the two remaining entries, the vdump command chooses the entry
with the most recent dump date, which is the level 3 entry.
·
The vdump command backs up all files that were created or modified
after the dump date of the level 3 entry.
·
The vdump command modifies the access time of each file in the
fileset.
2. To perform a full level 0 backup, enter a command similar to the
following:
% vdump -0 -u -f /dev/rmt1h /fs1
In this example, -0 specifies that all files in the fileset /fs1 will
be backed up to /dev/rmt1h; -u specifies vdump to update the
/etc/vdumpdates after a successful backup of the fileset.
3. When the backup saveset device is the character - (dash), the vdump
command writes to standard output. Thus, the vdump and vrestore
commands may be used in a pipeline expression to copy filesets. The
following are typical commands, both are equivalent:
# vdump -0 -f - /usr | (cd /mnt; vrestore -x -f -)
# vdump -0f - /usr | vrestore -xf - -D /mnt
4. For weekly tape backups, a set of 5 tapes per backed up fileset can be
used on a cyclical basis. Each month a level 0 backup is taken on a
set of fresh tapes that are saved until the next level 0 backup.
The following is a guideline for the level of backup to perform during
weekly, biweekly, and monthly periods.
______________________________
M Tu W Th F
______________________________
Weekly 0 3 2 5 4
Biweekly 0 3 2 5 4
0 9 8 9 9
Monthly 0 3 2 5 4
1 9 8 9 9
1 3 2 5 4
1 9 8 9 9
______________________________
FILES
/sbin/vdump
Specifies the vdump command path.
/etc/vdumpdates
Contains a list of filesets that were backed up, the date that each
file system was backed up, and the backup level.
/etc/fstab
Contains the full path names and mount points of filesets.
SEE ALSO
vrestore(8), mount(8), umount(8)