Janne Karhunen wrote:
Hi,
So effectively, it makes me sleep better. With it:
- I can rely on clients identifying the server correctly,
- I'm not exposing out anything that is not needed,
- Can tell by the address what this traffic is,
- Can be sure that packets are sent out via right interface
It might be even better if it would exit if -n is used when
no such interface is actually available. As I did it, it still
gambles here just as before.
After browsing thru "statd -n" flow, it is still not clear what will
happen if there are more than 2 interfaces used to export NFS shares ?
Using "statd -H", together with patches described in:
https://www.redhat.com/archives/cluster-devel/2007-April/msg00028.html ,
our cluster failover (with 4 IP interfaces per server) seemed to run
well without troubles. Note that 2/3 of the patch in 4-3 can be removed
*now* since it deals with moving server address from network header into
lockd internal structures - another similar patch (by Frank van
Maarseveen) was accepted into mainline kernel after our patch that has
the required functionality:
http://lkml.org/lkml/2007/7/10/553 .
So the following is our (-H) flow:
* Server dispatches statd with "-N" option that has a user mode script
(sample program fotest.c enclosed). It is expected the user mode script
could structure its nlm directory accordingly.
* Upon failover, the take-over server notifies clients with:
"/usr/sbin/sm-notify -f -v floating_ip_address -P an_sm_directory"
The advantages of "-H" approach over "-n" are (I think ?):
* It can handle multiple NFS export network interfaces.
* It knows which clients coming from which interfaces to allow selective
grace period for each interface.
In many ways, I would think "-n" should be obsolete ?
-- Wendy
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/stat.h> /* for mode_t */
void usage()
{
printf("\n");
printf(" check out \"man rpc.statd\":\n");
printf(" This callout program should receive callouts for\n");
printf(" NLM client monitor and unmonitor requests. It is\n");
printf(" run with 3 arguments: \n");
printf(" 1st: either add-client or del-client\n");
printf(" 2nd: the name of the client\n");
printf(" 3rd: the name of the server as known to the client.\n");
return;
}
int main (int argc, char* argv[])
{
char* file = "/tmp/NLM/from-ha";
mode_t rw_mode;
int rc, debug=0, i;
FILE *fd;
struct flock lock;
/* Open a file descriptor to the file. */
rw_mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH; /* 0644 */
fd = fopen(file, "a+");
fprintf(fd, "%s is invoked with %d arguments.\n", argv[0], argc - 1);
if (argc != 4) {
fprintf (fd, " error: invalid arguments\n");
debug = 1;
}
for (i = 1; i < argc; ++i)
fprintf (fd, " %s\n", argv[i]);
fclose(fd);
return 0;
}
