nvlogpg(8)nvlogpg(8)NAMEnvlogpg - Displays the log file of an AdvFS domain
SYNOPSIS
/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 } [-f]
/sbin/advfs/nvlogpg [-v | -B] log_id { -s | -e } page_offset
[record_offset [-f]]
/sbin/advfs/nvlogpg { domain_id | volume_id } -d dump_file
/sbin/advfs/nvlogpg [-v | -B] log_id -i fixid [-f]
/sbin/advfs/nvlogpg [-v | -B] volume_id -b block
OPTIONS
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. Dis‐
plays all subtransactions following the parent transaction. Specifies
the transaction ID to be displayed. Displays the active records. Dis‐
plays 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.
OPERANDS
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 for‐
mat: By default, the utility opens all volumes using block device spe‐
cial files. Specify the -r option to operate on the raw device (charac‐
ter 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.
DESCRIPTION
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 fixed-size header record, a num‐
ber 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 meta‐
data 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
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
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 fol‐
lowing 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 speci‐
fied page.
To display the parent transaction for transaction ID 456 in the file
domain domain_l, enter the following command: # /sbin/advfs/nvlogpg
domain_l -i 456
Following a Transaction
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 fol‐
lowing 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
To display the parent transaction and all of the subtransactions that
make up transaction ID 456 in the file domain domain_l, enter the fol‐
lowing command: # /sbin/advfs/nvlogpg domain_l -i 456 -f
Saving and Examining the Log File
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 com‐
mand 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
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 file‐
sets 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 con‐
secutive reads of the same file page may return unpredictable or con‐
tradictory 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 run‐
ning. The daemon, as it runs, activates the domain for a brief time.
If the nvlogpg 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
Specifies the command path. Specifies the volumes in the domain.
SEE ALSO
Commands: nvbmtpg(8), nvfragpg(8), tag2name(8), vfilepg(8), vsbmpg(8)
Files: advfs(4)nvlogpg(8)
