topic Re: Ntp problem in Operating System - HP-UX

Ntp problem

mark_150 — Thu, 17 Oct 2002 07:54:32 GMT

Hi all
I configured my system to use local ntp server using its internal clock.I installed patch phne_19710. My system contains one ntp server and three ntp clients. All hpux 10.20. I moved time on ntp server 2 minutes forward and after 10 minutes all clients
was synchronized to the server's time. But synchronization occurs immediately i.e. client's clock jumps 2 minutes in one second and this may cause application problem.
If this is correct?
Why ntp client doesn't correct its time slowly as in command ntpdate -B server?

Re: Ntp problem

John Bolene — Thu, 17 Oct 2002 12:06:21 GMT

Xntpd does it now with not much slew time.
Your NTP server should not vary much.

If you need to slew clock time, here is a C program that I use.

#include
#include
#include

int call_adjtime(delta, olddelta)
struct timeval *delta;
struct timeval *olddelta;
{
int retval;

retval = adjtime(delta, olddelta);
if(retval != 0) {
perror("adjtime");
}
return(retval);
}

main(argc, argv)
int argc;
char **argv;
{
char *prog;
struct timeval delta, olddelta;
int retval;

if((prog = (char *)rindex(*argv, '/')) == NULL) {
prog = *argv;
}
else {
prog++;
}

if(argc != 2) {
fprintf(stderr, "Usage: %s seconds\n", prog);
exit(1);
}

delta.tv_sec = atoi(argv[1]);
delta.tv_usec = 0;
olddelta.tv_sec = 0;
olddelta.tv_usec = 0;

retval = 1;
while(retval != 0) {
retval = call_adjtime(δ, &olddelta);
}
for(;;) {
delta.tv_sec = olddelta.tv_sec;
delta.tv_usec = olddelta.tv_usec;
call_adjtime(NULL, &olddelta);
if(olddelta.tv_sec == 0 && olddelta.tv_usec == 0) {
if(delta.tv_sec == 0 && labs(delta.tv_usec) < 100000) {
break;
}
else {
call_adjtime(δ, &olddelta);
call_adjtime(NULL, &olddelta);
}
}
printf("remained %d.%06d\n", olddelta.tv_sec, labs(olddelta.tv_usec));
sleep(1);
}
}

Re: Ntp problem

T G Manikandan — Thu, 17 Oct 2002 12:37:00 GMT

check what James has to tell here

http://bizforums.itrc.hp.com/cm/QuestionAnswer/1,,0x1e80e78d8c50d611abdb0090277a778c,00.html

Thanks

Re: Ntp problem

mark_150 — Thu, 17 Oct 2002 13:26:01 GMT

Thanks for all.

Re: Ntp problem

Sean OB_1 — Thu, 17 Oct 2002 13:31:55 GMT

my understanding is that the NTP client will sync with whatever the server says. Think of it this way. When daylight savings time comes around and you bump up your ntp server 1 hour, do you want the clients to make that same change immediately or spread it out slowly over the entire day?

If you need to adjust it slowly adjust the server slowly via the "date -a" command.

Re: Ntp problem

rick jones — Fri, 18 Oct 2002 17:26:54 GMT

whether a client slews time or does a stepwise adjustment depends on the settings and patches on the _client_ not the server, so you need to make sure that the client's have the slew patch installed and enabled.