voliod - Starts, stops, and reports on Logical Storage
Manager kernel I/O daemons
/sbin/voliod [-f] set count
Force the kill of the last I/O daemon. Without this
option, the I/O daemons can only be reduced to one. See
NOTES for an exception.
Sets the number of daemons to count.
The voliod utility starts, stops, or reports on Logical
Storage Manager kernel I/O daemons. When invoked with no
arguments, voliod prints the current number of volume I/O
daemons on the standard output. When invoked with the set
keyword, creates the number of daemons specified by count.
If more volume I/O daemons exist than are specified by
count, then the excess daemons will be terminated. If more
than the maximum number (64) are specified, the specified
number will be silently limited to that maximum.
The number of daemons necessary for general I/O handling
depends on system load and usage. One daemon for each CPU
on the system (or a minimum of two) is generally adequate,
unless volume recovery seems unusually slow.
Each I/O daemon starts in the background, creates an asynchronously
running kernel thread, and becomes a volume I/O
daemon. The voliod utility does not wait for these threads
Logical Storage Manager (LSM) automatically sets the number
of I/O daemons when the system starts, so it is usually
not necessary to set or change the number of I/O daemons
with this command.
On systems where the system attribute Max_LSM_IO_PERFORMANCE
is set to 1 (default is 0), the force option will
not allow you to kill the last daemon. You can reduce the
number of daemons to 1 but not 0. Attempts to kill the
last daemon will result in an error message like the following,
and will leave the number of daemons unchanged: #
voliod -f set 0 lsm:voliod: ERROR: VOL_IO_DAEMON_SET
failed: Permission denied
See sys_attrs_lsm(5) for more information.
LSM I/O daemons cannot be stopped directly through the use
The number of Logical Storage Manager I/O daemons currently
running can be determined only by running voliod;
I/O daemons do not appear in the list of processes
produced by the ps(1) command.
The voliod utility displays a diagnostic on the standard
error and exits if an error is encountered. If an I/O
error occurs within a spawned I/O daemon thread, then the
I/O is not reflected in the exit status for voliod. Otherwise,
voliod returns a nonzero exit status on errors, as
follows: Usage errors. voliod displays a usage message.
The requested number of daemons cannot be started, and
voliod reports the number that were successfully started.
All other errors.
The device used to start and report on volume I/O daemon
Commands: vold(8), voldctl(8)
Functions: fork(2), pthread(3)
Other: sys_attrs_lsm(5), volintro(8)
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