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nvfragpg(8)
NAME
nvfragpg - Displays the pages of an AdvFS frag file
SYNOPSIS
/sbin/advfs/nvfragpg [-v] [-f] frag_id
/sbin/advfs/nvfragpg [-v] [-f] frag_id page
/sbin/advfs/nvfragpg volume_id -b block [-v] [-f]
/sbin/advfs/nvfragpg domain_id fileset_id -d dump_file
OPTIONS
-b block
Specifies the logical block number of a disk block on an AdvFS volume.
-d dump_file
Specifies the name of a file that contains the output of this utility.
-f Displays the frag file free list.
-v Displays all the data in a frag file.
OPERANDS
frag_id
Specifies a frag file using the following format:
domain_id fileset_id | [-F] dump_file
The dump_file is a previously-saved copy of a frag file. Use the -F
option to force the utility to interpret the dump_file as a file
name when it has the same name as a domain 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 name, 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 fileset's tag
number, -T fileset_tag.
page
Specifies the file page number of a file.
DESCRIPTION
Use the nvfragpg utility to display information about frag file metadata.
Each fileset in an AdvFS domain has one frag file. Frag files are
collections of file fragments. The file fragments in a frag file are
grouped together by file fragment size into 16-page groups. File fragments
of 1 Kb or less are collected in one group; file fragments more than 1 Kb
up to 2 Kb are collected in another group; and so on, up to a group that
contains file fragments that are more than 6 Kb up to 7 Kb.
The first 1024 bytes of each group in a frag file contains the metadata for
the file fragments in the group.
A group is 128 Kb, so a group that collects 1 Kb fragments can hold at most
127 fragments, a group that collects 2 Kb fragments can hold at most 63
fragments, and so on. A group that collects 7 Kb fragments can hold, at
most, 18 fragments.
Displaying a Summary
The utility can display summary information about all pages in a frag file.
For example, you can display a summary of all the pages of the frag file
for domain_1 fileset_1 by entering the following command:
# /sbin/advfs/nvfragpg domain_1 fileset_1
The -f option displays which groups are on the free list for each frag
type. The -v option gives more information for the frag type of each
group. The following command displays the type of each group and the free
list for each frag type:
# /sbin/advfs/nvfragpg -v -f domain_1 fileset_1
Displaying One Frag File Page
You can specify that the utility display the metadata from a single group
of the frag file by specifying a page in the group. For example, you can
display the metadata from one group of the frag file for fileset_1 in
domain_1 by entering the following command:
# /sbin/advfs/nvfragpg domain_1 fileset_1 16
Because the metadata for the group is only on the first page of any 16-page
group, the page option is rounded down to the next lower multiple of 16.
Displaying Corrupted Volumes
If an AdvFS volume has become corrupted, the metadata needed to find the
frag file can be missing. However, you can specify a logical block number
(for a disk block) to display it, forcing the utility to interpret the
block as frag file metadata.
For example, to display the metadata on the frag page that contains
logical block number 1024 on volume 2 of AdvFS domain_1, use the following
command:
# /sbin/advfs/nvfragpg domain_1 2 -b 1024
If the specified block is not on a page boundary it is rounded down.
Saving a Frag File
Use the utility to read the frag file and save its metadata to another
file.
For example, to save the frag file metadata from a domain and volume index
domain 2 on a file named dump_domain.2, enter the following command:
# /sbin/advfs/nvfragpg domain 2 -d dump_domain.2
Later, you can examine the file dump_domain.2 to obtain a summary of its
frag file metadata by entering the following command:
# /sbin/advfs/nvfragpg dump_domain.2
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 filesets 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/nvfragpg
Specifies the command path.
/etc/fdmns/domain_name
Specifies the AdvFS volumes in domain_name.
SEE ALSO
Commands: nvbmtpg(8), nvlogpg(8), nvtagpg(8), vfilepg(8), vsbmpg(8)
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