[unix-history] / usr / src / usr.sbin / update / update.8

.\"	@(#)update.8	6.1 (Berkeley) %G%
.\"
.TH UPDATE 8 ""
.AT 3
.SH NAME
update \- periodically update the super block
.SH SYNOPSIS
.B /etc/update
.SH DESCRIPTION
.I Update
is a program that executes
the
.IR sync (2)
primitive every 30 seconds.
This insures that the file system
is fairly up to date in case of a crash.
This command should not be executed directly,
but should be executed out of the
initialization shell command file.
.SH "SEE ALSO"
sync(2), sync(8), init(8), rc(8)
.SH BUGS
With
.I update
running,
if the CPU is
halted just as
the
.I sync
is executed,
a file system can be damaged.
This is partially due to DEC hardware that
writes zeros when NPR requests fail.
A fix would be to have
.IR sync (8)
temporarily increment the system time by at
least 30 seconds to trigger the execution of
.I update.
This would give 30 seconds grace to halt the CPU.
Commit	Line	Data
6f65d36d	1	.\" @(#)update.8 6.1 (Berkeley) %G%
1f137805	2	.\"
6f65d36d	3	.TH UPDATE 8 ""
1f137805 KM	4	.AT 3
	5	.SH NAME
	6	update \- periodically update the super block
	7	.SH SYNOPSIS
	8	.B /etc/update
	9	.SH DESCRIPTION
	10	.I Update
	11	is a program that executes
	12	the
	13	.IR sync (2)
	14	primitive every 30 seconds.
	15	This insures that the file system
	16	is fairly up to date in case of a crash.
	17	This command should not be executed directly,
	18	but should be executed out of the
	19	initialization shell command file.
	20	.SH "SEE ALSO"
b2319459	21	sync(2), sync(8), init(8), rc(8)
1f137805 KM	22	.SH BUGS
	23	With
	24	.I update
	25	running,
	26	if the CPU is
	27	halted just as
	28	the
	29	.I sync
	30	is executed,
	31	a file system can be damaged.
	32	This is partially due to DEC hardware that
	33	writes zeros when NPR requests fail.
	34	A fix would be to have
b2319459	35	.IR sync (8)
1f137805 KM	36	temporarily increment the system time by at
	37	least 30 seconds to trigger the execution of
	38	.I update.
	39	This would give 30 seconds grace to halt the CPU.