voliod(1M) Volume Manager Utilities voliod(1M)
NAME
voliod - Starts, stops, and reports Volume Manager kernel
daemons
SYNOPSIS
voliod
voliod [ -f ] start [ count ]
voliod stop
voliod [ -fn ] logio volume ...
voliod stoplogio volume ...
DESCRIPTION
The voliod utility starts, stops, or reports on Volume
Manager error daemons and volume log I/O daemons. An error
daemon is a process that the volume driver (see vol(7)) uses
for extended error-recovery operations. At least one error
daemon is required by the volume driver to process these
recovery operations, with each error daemon serially
processing one operation at a time. A volume log I/O daemon
is used by the virtual disk driver to schedule writes for
volumes that require logging.
OPERATION
When invoked with no arguments, voliod prints the current
number of volume error daemons on the standard output. This
is determined by opening the /dev/voliod device and issuing
the VOLIODAEMONCNT ioctl.
When invoked with the start keyword, one or more volume
error daemons are started. If no count is specified, then
one error daemon is started; otherwise, the requested number
of daemons are started. This number is silently truncated
to 10. Each error daemon is started by using fork(2) to
create an asynchronously-running process, which detaches
itself from the controlling terminal and issues the
VOLIODAEMON ioctl on the /dev/voliod device to become a
volume error daemon. The voliod utility does not wait for
these processes to complete.
When invoked with the keyword stop, voliod stops all
currently running error daemons that were started with the
voliod utility. The ps(1M) utility is used to find the
process ID for all voliod processes that are not attached to
a terminal.
When invoked with the keyword logio, voliod creates a volume
log I/O daemon for each of the volumes named in the operand
list. Each log I/O daemon is started by using fork(2) to
create an asynchronously running process, which detaches
itself from the controlling terminal and issues the
VOLLOGIODAEMON ioctl on the /dev/voliod device.
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voliod(1M) Volume Manager Utilities voliod(1M)
When invoked with the keyword stoplogio, voliod kills any
logging daemons associated with the named volumes.
OPTIONS
The following options are used by voliod:
-n Do not print error messages that may be generated
as a result of starting a logio daemon twice on
the same volume.
-f Create daemons in foreground rather than
background. Only one foreground daemon process
can be created in a single invocation of voliod.
EXIT CODES
The voliod utility prints a diagnostic on the standard
error, and exits if an error is encountered. If an error
occurs within a forked error daemon process, then the error
is not reflected in the exit status for voliod. Otherwise,
voliod returns a nonzero exit status on errors.
Usage errors result in an exit status of 1 and a usage
message. If the requested number of daemons cannot be
created, then the exit status is 2, and the number of
daemons that were successfully started is reported. If any
other error occurs, the exit status is 3.
FILES
/dev/voliod
The device used to report on and start volume I/O
daemon processes.
CAVEATS
Because a simple method is used to scan the output of ps,
the stop operation kills all utilities called voliod that
are detached from a terminal, even if they are not really
volume error daemons.
NOTE
Volume log I/O daemons are created automatically by vold
when they are needed, and are killed automatically when they
are no longer needed. Log I/O daemons cannot be killed
directly through the use of signals.
SEE ALSO
ps(1M), fork(2), volintro(1M), voliod(7), and vol(7).
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