Интерактивная система просмотра системных руководств (man-ов)
syncer (4)
>> syncer (4) ( FreeBSD man: Специальные файлы /dev/* )
BSD mandoc
NAME
syncer
- file system synchronizer kernel process
SYNOPSIS
DESCRIPTION
The
kernel process helps protect the integrity of disk volumes
by flushing volatile cached file system data to disk.
The kernel places all
vnode(9)Ns's
in a number of queues.
The
process works through the queues
in a round-robin fashion,
usually processing one queue per second.
For each
vnode(9)
on that queue,
the
process forces a write out to disk of its dirty buffers.
The usual delay between the time buffers are dirtied
and the time they are synced
is controlled by the following
sysctl(8)
tunable variables:
Variable Ta Default Ta Description
kern.filedelay Ta 30 Ta time to delay syncing files
kern.dirdelay Ta 29 Ta time to delay syncing directories
kern.metadelay Ta 28 Ta time to delay syncing metadata
The
process is a descendant of the
`update'
command, which appeared in
AT&T System
v6 ,
and was usually started by
/etc/rc
when the system went multi-user.
A kernel initiated
`update'
process first appeared in
Fx 2.0 .
BUGS
It is possible on some systems that a
sync(2)
occurring simultaneously with a crash may cause
file system damage.
See
fsck(8).
