Hello,
what should it be in 3.2 the version of NFS default ISO created on engine?
Can I change it afterwards
During engine setup I was only requested if I wanted it or not:

(f18 with ovirt-nightly repo and 3.2.0-1.20130113.gitc954518)
Configure NFS share on this server to be used as an ISO Domain? ['yes'| 'no']  [yes] : 
Local ISO domain path  [/var/lib/exports/iso] : /ISO

ok

Current situation on engine regarding iptables

[root@f18engine ~]# iptables -L -n
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           
ACCEPT     icmp --  0.0.0.0/0            0.0.0.0/0            icmptype 255
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            ctstate RELATED,ESTABLISHED
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW tcp dpt:22
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW tcp dpt:80
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW tcp dpt:443
ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW udp dpt:111
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW tcp dpt:111
ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW udp dpt:892
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW tcp dpt:892
ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW udp dpt:875
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW tcp dpt:875
ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW udp dpt:662
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW tcp dpt:662
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW tcp dpt:2049
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW tcp dpt:32803
ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0            ctstate NEW udp dpt:32769
REJECT     all  --  0.0.0.0/0            0.0.0.0/0            reject-with icmp-host-prohibited

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         


ANd regarding nfs:
[root@f18engine ~]# ps -ef|grep [n]fs
root      1134     2  0 Jan15 ?        00:00:00 [nfsd4]
root      1135     2  0 Jan15 ?        00:00:00 [nfsd4_callbacks]
root      1136     2  0 Jan15 ?        00:00:00 [nfsd]
root      1137     2  0 Jan15 ?        00:00:00 [nfsd]
root      1138     2  0 Jan15 ?        00:00:00 [nfsd]
root      1139     2  0 Jan15 ?        00:00:00 [nfsd]
root      1140     2  0 Jan15 ?        00:00:00 [nfsd]
root      1141     2  0 Jan15 ?        00:00:00 [nfsd]
root      1142     2  0 Jan15 ?        00:00:00 [nfsd]
root      1143     2  0 Jan15 ?        00:00:00 [nfsd]

[root@f18engine ~]# systemctl status rpcbind.service
rpcbind.service - RPC bind service
 Loaded: loaded (/usr/lib/systemd/system/rpcbind.service; enabled)
 Active: active (running) since Tue, 2013-01-15 13:38:46 CET; 1 day and 2h ago
Process: 1098 ExecStart=/sbin/rpcbind -w ${RPCBIND_ARGS} (code=exited, status=0/SUCCESS)
Main PID: 1128 (rpcbind)
 CGroup: name=systemd:/system/rpcbind.service
 └ 1128 /sbin/rpcbind -w

Jan 15 13:38:46 f18engine.ceda.polimi.it systemd[1]: Started RPC bind service.

When host tries to attach ISO it fails
host is f18 with ovirt-nightly and  
vdsm-4.10.3-0.78.gitb005b54.fc18.x86_64

I noticed 
[root@f18ovn03 ]# ps -ef|grep mount
root      1692     1  0 14:39 ?        00:00:00 /usr/sbin/rpc.mountd
root      6616  2334  0 15:17 ?        00:00:00 /usr/bin/sudo -n /usr/bin/mount -t nfs -o soft,nosharecache,timeo=600,retrans=6,nfsvers=3 f18engine:/ISO /rhev/data-center/mnt/f18engine:_ISO
root      6617  6616  0 15:17 ?        00:00:00 /usr/bin/mount -t nfs -o soft,nosharecache,timeo=600,retrans=6,nfsvers=3 f18engine:/ISO /rhev/data-center/mnt/f18engine:_ISO
root      6618  6617  0 15:17 ?        00:00:00 /sbin/mount.nfs f18engine:/ISO /rhev/data-center/mnt/f18engine:_ISO -o rw,soft,nosharecache,timeo=600,retrans=6,nfsvers=3
root      6687  4147  0 15:17 pts/0    00:00:00 grep --color=auto mount

The problem here is option 
nfsvers=3

in fact if I manually run on node

[root@f18ovn03 ]# mount -t nfs -o nfsvers=4 f18engine:/ISO  /p
--> OK

and
[root@f18ovn03 ]# mount
...
f18engine:/ISO on /p type nfs4 (rw,relatime,vers=4.0,rsize=524288,wsize=524288,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=10.4.4.59,local_lock=none,addr=10.4.4.60)

while
# mount -t nfs -o nfsvers=3 f18engine:/ISO  /p
--> KO 
stalled

What should I change, engine or host or both?

Thanks in advance,
Gianluca