Hi All!
I am a really newbie in samba (in english too).
Problem:
So I installed a Samba 3.0.4 (ADS member server) in the sun box with two
ADS. Everything work great, but if
the primary ADS (lower IP) is crashed, then the wbinfo -t, wbinfo -u ...
answers has a very long
timeout (~8-9 min).
Descriptions (after a lot of debugging):
* The Sun box has same time for initialize a TCP connection (SYN_SENT) if
the destination host not running.
- Try on linux how much is yours machine with "# date; telnet
192.168.0.1; date" (IP must good on your network and not exist on it)
* Samba has a cache for the unavailable ADS (KDC) (but this expire after
30 seconds)
- the samba has an ordered list for the KDC (ordered by IP)
Problem continue:
So, if the primary ADS (lower IP) will be crash, then the samba will do
this (if somebody want something from the Samba server):
* Get the ordered list which is int the /etc/krb5/krb5.conf (kdc = ...,
kdc = ...)
* Trying the connect to the ADS:389 (first pass from the ordered list
and approx 8-9minute )
- if cannot connect to it, then put this ADS into the
"failed_connection_cache" (but if it is expired (30sec) then remove
from
cache)
So this allways try to connect to the first ADS because the cache
expire time is allways expired. This is a typical deadlock syndrome.
Solutions:
1. tuning TCP stack on Sun box to 35 sec (on linux I don't know how must
do it)
ndd -set /dev/tcp tcp_rexmit_interval_extra 0
ndd -set /dev/tcp tcp_rexmit_interval_initial 500
ndd -set /dev/tcp tcp_ip_abort_interval 20000
ndd -set /dev/tcp tcp_ip_abort_cinterval 20000
2. Setup the FAILED_CONNECTION_CACHE_TIMEOUT constant
- #define FAILED_CONNECTION_CACHE_TIMEOUT 30 /* Seconds between
attempts */
+ #define FAILED_CONNECTION_CACHE_TIMEOUT 3600 /* One hour, it is
enough I think */
Problem with the solutions:
If the all ADS will be crash, then you must restart the samba after the
ADS's come back because we has
a very long cache expire time.
So, I hope this article help for everybody who has same problem...
Pal
