nvlogpg - Displays the log file of an AdvFS domain
/sbin/advfs/nvlogpg log_id
/sbin/advfs/nvlogpg [-v | -B] log_id page [record_offset
[-f]]
/sbin/advfs/nvlogpg [-v | -B] log_id { -R | -a }
/sbin/advfs/nvlogpg [-v | -B] log_id { -s | -e }
[page_offset]
/sbin/advfs/nvlogpg domain_id | volume_id -d dump_file
/sbin/advfs/nvlogpg [-v | -B] volume_id -b block
Displays all the pages in the log file. Brief. Displays
only the transaction ID for each log file entry. Specifies
the logical block number of a disk block on an AdvFS
volume. Specifies the name of a file that will hold the
contents of the specified log file. Displays the last
active record in the log file--the end of the log file.
Displays all subtransactions following the parent transaction.
Displays the active records. Displays the first
active record in the log file--the start of the log file.
Verbose. Displays all the data in a specified log, page,
or record.
Specifies a log file in an AdvFS domain or a log file that
has been saved by the utility as a dump_file. Use the
following format: Specify the -F option to force the utility
to interpret the name you supply as a file name.
Specifies an AdvFS file domain using the following format:
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. Specifies an
AdvFS volume using the following format: 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. Specifies the name of
a file that contains the output from this utility.
Specifies the file page number of a file. Specifies
the offset relative to the start or the end of
the active region in the log file. Specifies a
byte offset in a page of the log file.
The nvlogpg command locates the log file of an AdvFS file
domain and displays records from it in various ways.
The log file for a domain is a bitfile, organized as an
array of 8 Kb disk pages. Each page consists of a fixedsize
header record, a number of variable-sized data
records, and a fixed-size trailer record. Each data record
consists of a fixed-size header and a variable amount of
data.
The log file for a domain contains the metadata, the log,
of each transaction. Before a transaction is written to
disk, its logged metadata is written to disk. Because the
log of a transaction contains the information necessary to
redo the transaction, the file system can maintain consistency
on disk and recover from system failures when they
occur. These transactions and the metadata they include
are used to replay transactions that did not complete, for
example if the system crashed, when the domain is next
activated.
Displaying a Summary [Toc] [Back]
You can specify a domain or volume name to display a summary
of the log file that includes its location, size, and
the location of its starting and ending records.
For example, to display a summary of the log file for
domain domain_1, enter the following command: #
/sbin/advfs/nvlogpg domain_1
Displaying Log File Pages and Records [Toc] [Back]
There are several ways you can specify log file pages and
records.
To display page five of a log file for a domain that you
know is on device rz5a, enter the following command: #
/sbin/advfs/nvlogpg rz5a 5
To display the record at byte offset 234 in page seven of
the log file in the domain named domain_1, enter the following
command: # /sbin/advfs/nvlogpg domain_1 7 234
You can use the command to find the start or the end of
the active log. The start of the log is the first record
whose data is not yet written to the metadata files. The
end of the log is the last record that has been written to
the log. For example, to display the first record in
domain domain_1 whose record is not yet written to metadata
files, enter the following command: #
/sbin/advfs/nvlogpg domain_1 -s
To display the end of the log in domain domain_1--the last
record that has been written to the log--enter the following
command: # /sbin/advfs/nvlogpg domain_1 -e
You can use the utility to display pages and records that
are after or before after the start or the end of the
active log. For example, to display the second page after
the start of the log file for domain_1, enter the following
command: # /sbin/advfs/nvlogpg domain_1 -s 2
To display the page before the end of the log for
domain_1, enter the following comand: #
/sbin/advfs/nvlogpg domain_1 -e -1
To display the record at byte offset 234 on the page of
the log that holds the last log record in the log file for
domain_1, enter the following command: #
/sbin/advfs/nvlogpg domain_1 -e 0 234
The page offset is relative to the page that contains the
start and end records of the log file. The record offset
is relative to the specified page.
Following a Transaction [Toc] [Back]
The utility can follow the log records that belong to one
transaction. For example, you can follow a set of log
records from one transaction by specifying a record and
the -f option.
Specify one particular log record and use the -f option.
For example, to display the log record at page 1, byte
offset 128, and all the following records that belong to
the same transaction, enter: # /sbin/advfs/nvlogpg
domain_1 1 128 -f
Because the -s option also specifies one record, the -f
option can be used with it. For example: #
/sbin/advfs/nvlogpg domain_1 -s -f
Saving and Examining the Log File [Toc] [Back]
You can use the nvlogpg command to write the log file to
another file, a dump_file, and later use the command to
examine it.
For example, you can extract the log file for domain
domain_1 and write it to a file named domain_1_log by
entering the following command: # /sbin/advfs/nvlogpg
domain_1 -d domain_1_log
Later, you can examine the log file you extracted. Use
the same command syntax on the file as you did for the log
in the domain, except you use the -F option to force the
utility to interpret the name as a file name, in case
there is a domain or volume with the same name.
For example, you can display a summary of the file,
domain_1_log by entering the following command: #
/sbin/advfs/nvlogpg -F domain_1_log
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.
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 nvlogpg utility
fails in this situation, run it again.
The utility returns a 0 (zero) on success, otherwise it
returns a nonzero value and an error diagnostic.
Specifies the command path. Specifies the volumes in the
domain.
Commands: nvbmtpg(8), nvfragpg(8), tag2name(8),
vfilepg(8), vsbmpg(8)
Files: advfs(4)
nvlogpg(8)
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