[Linux-cluster] Problems with SAMBA server on Centos 51 virtual xen guest with iSCSI SAN

[Paolo Marini]

I have implemented a cluster of a few xen guest with a shared GFS 
filesystem residing on a SAN build with openfiler to support iSCSI storage.

Physical servers are 3 machines implementing a physical cluster, each 
one equipped with quad xeon and 4 G RAM. The network interface is based 
on channel bonding with LACP (on the physical hosts) having an aggregate 
of 2 gigabits ethernet per physical host, the switch supports LACP and 
has been configured accordingly.

Virtual servers are based on xen nodes on top of the physical server 
with shared storage on iSCSI and GFS.

The networking is based on a cluster private network (for cluster 
heartbeat and cluster communication + iSCSI) and an ethernet alias for 
the LAN to which the users are connected.

One of the cluster xen nodes is used for implementing a samba PDC (no 
failover of the service, plain samba, single samba server on the LAN) 
plus ldap server; samba works with ldap for users authentication. 
Storage for the samba server is on the SAN.

I continue to receive complaints from my users due to the fact that 
sometimes copying file generates errors, plus problems related to office 
usage (we still use the old Office 97 on some machines). The samba 
configuration is more or less the same as that correctly working on the 
previous physical machine, on which those problems were not present.

The problems generate these log entries on /var/log/samba/smbd:

[2008/04/02 19:00:50, 0] lib/util_sock.c:get_peer_addr(1232)
  getpeername failed. Error was Transport endpoint is not connected
[2008/04/02 19:05:32, 0] lib/util_sock.c:get_peer_addr(1232)
  getpeername failed. Error was Transport endpoint is not connected
[2008/04/02 19:05:32, 0] lib/util_sock.c:get_peer_addr(1232)
  getpeername failed. Error was Transport endpoint is not connected

And on the client machine log also on /var/log/samba

[2008/04/02 19:04:34, 0] lib/util_sock.c:read_data(534)
  read_data: read failure for 4 bytes to client 192.168.13.240. Error = 
Connection reset by peer
[2008/04/02 19:04:34, 1] smbd/service.c:close_cnum(1230)
  amhwq53p (192.168.13.240) closed connection to service tmp
[2008/04/02 19:04:34, 1] smbd/service.c:close_cnum(1230)
  amhwq53p (192.168.13.240) closed connection to service stock
[2008/04/02 19:04:34, 0] lib/util_sock.c:write_data(562)
  write_data: write failure in writing to client 192.168.13.240. Error 
Broken pipe
[2008/04/02 19:04:34, 0] lib/util_sock.c:send_smb(769)
  Error writing 75 bytes to client. -1. (Broken pipe)
[2008/04/02 19:04:34, 1] smbd/service.c:make_connection_snum(1033)

They seem similar to problems related to poor connectivity or problem in 
the network; however, these problems are new and were never found before 
switching to the clustered architecture. Also no problem have been found 
so far on the other xen nodes serving the same GFS filesystem (different 
dirs !) for NFS or other services.

Also putting the option

posix locking = no

on the smb.conf file did not help.

Any idea from someone else facing the same problems ?

thanks, Paolo