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nvbmtpg(8)
NAME
nvbmtpg - Display pages of an AdvFS BMT file
SYNOPSIS
/sbin/advfs/nvbmtpg [-R] [-v] { domain_id | bmt_id } [-f]
/sbin/advfs/nvbmtpg [-R] [-v] bmt_id page [-f]
/sbin/advfs/nvbmtpg [-R] [-v] bmt_id page mcell [-c]
/sbin/advfs/nvbmtpg [-R] [-v] bmt_id [-a]
/sbin/advfs/nvbmtpg [-R] [-v] domain_id fileset_id [file_id] [-c]
/sbin/advfs/nvbmtpg [-R] [-v] { domain_id | volume_id } -l
/sbin/advfs/nvbmtpg [-R] [-v] bmt_id -s b block [-c]
/sbin/advfs/nvbmtpg [-R] [-v] domain_id fileset_id -s f frag [-c]
/sbin/advfs/nvbmtpg [-R] [-v] { bmt_id | domain_id [fileset_id] } -s t tag
[-c]
/sbin/advfs/nvbmtpg [-R] [-v] volume_id -b block [mcell]
/sbin/advfs/nvbmtpg [-R] volume_id -d dump_file
OPTIONS
-a Display all the pages in the BMT.
-b block
Specifies the logical block number of a disk block on an AdvFS volume.
-c Display the entire chain of mcells. Alternatively, continue to search.
-d dump_file
Specifies the name of a file that will hold the contents of the
specified BMT file.
-f Display the number of free mcells.
-l Display the deferred delete list of mcells.
-R Specifies that information about the Reserved Bitmap Metadata Table
(RBMT) is to be displayed, instead of information about the BMT.
-s b block
Specifies the logical block number of a disk block on an AdvFS volume.
When you use this option, the utility searches the specified BMT file
for a mcell that has an extent record for a file that contains the
specified block.
-s f frag
Specifies the number of a file fragment in the frag file for a fileset.
When you use this option, the utility searches all BMT files (there is
one on each AdvFS volume) for a mcell that:
· Belongs to a file in the specified fileset
· Has an attribute record that indicates the file is using the
specified frag ID.
-s t tag
Specifies the file tag number. When you use this option, the utility
searches one or all of the BMT files for a mcell with this tag.
-v Display all the data in a specified mcell.
OPERANDS
bmt_id
Specifies the BMT file on an AdvFS volume or a BMT file that has been
saved by the utility as a dump_file. Use the following format:
volume_id | [-F] dump_file
Specify the -F option to force the utility to interpret the name
you supply as a file name.
domain_id
Specifies an AdvFS file domain using the following format:
[-r] [-D] domain
By default, the utility opens all volumes using block device
special files. Specify the -r option to operate on the raw device
(character device special file) of the domain instead of the block
device. Specify the [-D] option to force the utility to interpret
the name you supply in the domain argument as a domain name.
volume_id
Specifies an AdvFS volume using the following format:
[-V] volume | domain_id volume_index
Specify the -V option to force the utility to interpret the name
you supply in the volume argument as a volume name. The volume name
argument also can be a full or partial path for the volume, for
example /dev/disk/dsk12a or dsk12a. Specifying a partial path name
always opens the character device special file.
Alternatively, specify the volume by using arguments for its
domain, domain_id, and its volume index number, volume_index.
fileset_id
Specifies an AdvFS fileset using the following format:
[-S] fileset | -T fileset_tag
Specify the [-S] option to force the command to interpret the name
you supply as a fileset name. Specify the fileset by entering
either the name of the fileset, fileset, or the file's fileset tag
number, -T fileset_tag.
file_id
Specifies a file name in the following format:
file | [-t] file_tag
Specify the file by entering either the fileset relative pathname,
file, or the file's tag number, -t file_tag.
mcell
Specifies the number of a metadata cell (mcell) in a BMT file.
page
Specifies the file page number of the BMT file.
DESCRIPTION
The nvbmtpg utility formats, dumps, and displays pages of the Bitfile
Metadata Table (BMT) files.
For Tru64 UNIX Version 5.0 and beyond, the utility also formats, dumps, and
displays pages of the Reserved Bitfile Metadata Table (RBMT) files. RBMT
files are metadata structures that extend BMT files.
BMTs are composed of mcells. Each file in an AdvFS domain is described by
a collection of mcells. The mcells for each file are chained together.
The first mcell in a chain is called the primary mcell.
There is one BMT file on each volume of an AdvFS domain.
A BMT file is an array of 8 Kbyte file pages, each page containing a header
and an array of metadata cells (mcells). The purpose of a BMT file is to
contain all the metadata for all files that are stored on an AdvFS volume.
This utility has the following functions:
· Display a summary of the BMT on one AdvFS volume or a summary of all
the BMT files (there is one per volume) in a domain.
· Display a page of mcells or one mcell or a chain of mcells. The page
can be specified by a BMT page number or a volume block number. An
mcell can be specified by a number or by specifying the primary mcell
of a file.
· Search for an mcell. The search can be for an extent that maps a
volume block or a file that uses a given frag ID.
Display a Summary of BMTs
By specifying just a domain and (possibly) the -f option, you cause the
utility to display a summary of the BMT on all volumes in the domain.
Without the -f option, the summary shows how long the BMT is, in pages.
With the -f option, the summary also displays how many free mcells are in
the BMT for each volume.
For example, the following command causes the utility to read BMT page 0
(zero) in every volume of the domain and display the number of pages in
each BMT, the number of extents used to describe the BMT, and the number of
free mcells in BMT page 0:
# /sbin/advfs/nvbmtpg -r my_domain
For example, the following command causes the utility to read the entire
BMT in every volume of the domain and display the number of pages in each
BMT, the number of extents use, and the number of free mcells in BMT page
0. In addition, the utility displays the number of free mcells not on page
0:
# /sbin/advfs/nvbmtpg my_domain -f
Specifying just a volume (and possibly the -f option) displays a summary
for the BMT on that volume. Two examples are:
# /sbin/advfs/nvbmtpg -D my_domain 1 -f
# /sbin/advfs/nvbmtpg dsk12c
Displaying a BMT Page
The utility can display information from a specified BMT page. It can
display the whole page or one mcell on a page. It can also display all
the mcells on an AdvFS volume.
Each AdvFS volume contains its own BMT file, so you must specify the volume
and the page to get the page you want to display. For example, to display
the first page (page 0) of the BMT on volume /dev/disk/dsk5a, you would
enter the following command:
# /sbin/advfs/nvbmtpg /dev/disk/dsk5a 0
The volume can also be specified by domain name and volume index. For
example, to display page 0 or volume 1 of the domain_1 domain, enter the
following command:
# /sbin/advfs/nvbmtpg domain_1 1 0
You can specify a single mcell to display. For example, you could display
mcell 5 on page 4 of the third AdvFS volume in the file domain domain_1 by
entering the following command:
# /sbin/advfs/nvbmtpg domain_1 3 4 5
To display all the mcells on dsk5a, enter the following command:
# /sbin/advfs/nvbmtpg /dev/disk/dsk5a -a
Note
This use of the command can generate megabytes of output: use it
carefully.
Displaying Primary mcells
The primary mcell of a file in an AdvFS domain is the first mcell in a
chain of mcells that describe the file. The primary mcell for a fileset in
an AdvFS domain is the first mcell in a chain of mcells that describes the
fileset. Use this utility to locate and display the primary mcell of a file
or a fileset.
To locate the primary mcell (for either a file or a fileset) you must
uniquely identify it in the command line. A fileset can be uniquely
identified by its domain and fileset names. A file can be uniquely
identified by its domain, fileset, fileset relative path name.
For example, you can display the primary mcell for a file file_1 in a
directory dir_1 in a fileset fileset_1 in a domain domain_i by entering the
following command:
# /sbin/advfs/nvbmtpg domain_1 fileset_1 dir_1/file_1
You can also display the primary mcell by its tag number. For example, if
the file_1 had a tag number of 5, the command to display the primary mcell
for the file would be:
# /sbin/advfs/nvbmtpg domain_1 fileset_1 -t 5
Note
If there is no danger of confusing tag 5 with a file named 5 in the
root directory, then the -t option is optional.
Displaying mcell Chains
The mcells that describe one BMT file are chained, and are not necessarily
contiguous. Use the [-c] option to display these mcell chains. For
example, display the entire chain of mcells that describe the file named
file_1 in the root directory of the fileset named fileset_1 in the domain
named domain_1, enter the following command:
# /sbin/advfs/nvbmtpg domain_1 fileset_1 file_1 -c
Displaying the Deferred Delete List
Each volume in a domain has a linked list of mcells which represent storage
to be freed. The -l option displays the mcells in this list. If just the
domain is specified, the option displays the deferred delete list for every
volume in the domain. For example:
# /sbin/advfs/nvbmtpg domain_1 -l
If an AdvFS volume is specified, the option displays the deferred delete
list for that volume. For example:
# /sbin/advfs/nvbmtpg dsk5c -l
Displaying Corrupted Volumes
If the volume is corrupted, the metadata structure needed to find specific
mcells can be missing. In this case, you can specify a disk block and the
utility displays a page containing the specified disk block.
For example: you have a corrupted AdvFS domain, but you have the logical
block number of a BMT page. To display logical block number 1024 on AdvFS
volume /dev/disk/dsk5c in AdvFS domain domain, forcing it to be formatted
as a BMT page, you use the following command:
# /sbin/advfs/nvbmtpg dsk5c -b 1024
For example: you have a corrupted AdvFS domain, but you have a domain and
an index number and the logical block number of a BMT page. To display
logical block number 1024 on AdvFS volume 2 in AdvFS domain domain, forcing
it to be formatted as a BMT page, you use the following command:
# /sbin/advfs/nvbmtpg domain 2 -b 1024
Saving a BMT File
Use the utility to read the BMT file and save it to another file. Later,
you can use the utility to display information from this dump_file.
For example, to save the BMT file from volume index 2 in a domain named
domain_1 to a file named dump_domain.2 in the current working directory,
enter the following command:
# /sbin/advfs/nvbmtpg domain_1 2 -d dump_domain.2
Later, you can examine the file dump_domain.2 to obtain a summary of its
BMT pages, by entering the following command:
# /sbin/advfs/nvbmtpg dump_domain.2
You can also use the utility to display other information from the
dump_file, such as: any mcell, a page of mcells, or the mcell free list in
a page of mcells.
Searching for Disk Blocks
You can determine which file is using a logical block number by searching
for and displaying the mcell that contains a file extent that includes that
block. The mcell contains the fileset tag and the file tag number of the
file that includes that block. Use the tag2name utility to find the file
name.
For example, you can search for a mcell record that describes the use of a
disk block on an AdvFS volume. If you want to determine which file was
using logical block number 1234 on AdvFS volume dsk12c, you can enter the
following command:
# /sbin/advfs/nvbmtpg dsk12c -s b 1234
A given block should only appear in one mcell. However, a corrupted volume
may have two or more extents describing the same block. Therefore, if you
want to find the disk block shown above and continue the command, searching
for any files that also have a file extent that includes block 1234, you
can enter the following command:
# /sbin/advfs/nvbmtpg dsk12c -s b 1234 -c
Searching for Fragment Files
AdvFS creates one fragment file for each fileset in an AdvFS file domain.
You can determine the file that is using a given file fragment ID and
display the primary mcell for that file.
For example, if you want to determine which file in domain domain and
fileset fileset was using the fragment id 1234, you can enter the following
command:
# /sbin/advfs/nvbmtpg domain fileset -s f 1234
A given fragment ID can only be used by one file in a fileset. However, a
corrupted fileset may have a given fragment ID used by two or more files.
Therefore, if you want to find the fragment file ID above and continue the
command, searching for any additional files that own the file fragment, you
can enter the command:
# /sbin/advfs/nvbmtpg domain fileset -s f 1234 -c
Searching for a Specified Tag
If you specify a domain, a fileset and a file tag (as shown before in the
section on displaying primary mcells) the utility uses other metadata files
in the domain to find the primary mcell in the BMT. However, the utility
can also search for a mcell with a given tag without using any other
metadata files if you specify the -s t option.
This option searches a saved BMT file, or the BMT on one volume, or all the
BMT files in a domain for an mcell with the tag you specify. If you specify
a domain and fileset, the utility narrows the search to mcells that belong
to the fileset. However, if you specify a fileset, the utility must use
other metadata files in the domain. In this case, the search syntax
displays the first mcell it finds that contains the specifed tag. This
mcell could be (but may not be) the primary mcell for the file. To
continue the search and display all mcells for the specified tag, add the
-c option.
The following example searches all BMT files for mcells with tag 123:
# /sbin/advfs/nvbmtpg domain_1 -s t 123 -c
The following example searches a saved BMT file for mcells that belong to
file tag 456:
# /sbin/advfs/nvbmtpg save_bmt -s t 456 -c
NOTES
An active domain, which is a domain with one or more of its filesets
mounted, has all of its volumes opened using block device special files.
These devices cannot be opened a second time without first being unmounted.
However, the character device special files for the volumes can be opened
more than once while still mounted.
It can be misleading to use this utility on a domain with mounted filesets
because the utility does not synchronize its read requests with AdvFS file
domain read and write requests.
For example, the AdvFS can be writing to the disk as the utility is reading
from the disk. Therefore, when you run the utility, metadata may not have
been flushed in time for the utility to read it and consecutive reads of
the same file page may return unpredictable or contradictory results. [The
domain is not harmed.]
To avoid this problem, unmount all the fileset in the domain before using
this utility.
RESTRICTIONS
The utility can fail to open a block device, even when there are no
filesets mounted for the domain and the AdvFS daemon, advfsd is running.
The daemon, as it runs, activates the domain for a brief time. If the
utility fails in this situation, run it again.
EXIT STATUS
The utility returns a 0 (zero) on success, otherwise it returns a nonzero
value and an error diagnostic.
FILES
/sbin/advfs/nvbmtpg
Specifies the command path.
/etc/fdmns/domain_name
Specifies the AdvFS volumes in domain_name
SEE ALSO
Commands: vfilepg(8), nvfragpg(8), nvlogpg(8), vsbmpg(8), nvtagpg(8),
tag2name(8)
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