Cannot copy over 7MB file to Samba cluster on Centos 6.5

Question

I have followed these instructions (with lots of updates since it's old) to get working two nodes Samba cluster in my VirtualBox lab. It's almost done, but I experience strange issue and does not know where to search for solution:

I cannot copy files bigger than 7MB from Windows desktop to this share. Smaller ones I copy with no issue. Error is "There is a problem accessing \192.168.1.128\public" "Make sure you are connected to the network and try again".

UPDATE: I just restarted VirtualBox host and power on both CentOs VMs. Using Windows desktop I managed to create a new folder and to copy 1Gb file to the share successfully. After copy is finished I cannot copy big file again (batch of small ones are copied ok).

UPDATE 2: I just realized I'm able to copy files to share root (public) but not to folders I created from clients (Windows 7 and Ubuntu which) UPDATE 2a: I was wrong, I did managed to copy more gigabytes on root share (public) from Windows before I start hitting the same error, from Ubuntu file is always copied until end, but with error message at the very end (Invalid argument)

Any ideas?

[root@smb1 ~]# testparm -s
Load smb config files from /etc/samba/smb.conf
rlimit_max: increasing rlimit_max (1024) to minimum Windows limit (16384)
WARNING: The "idmap backend" option is deprecated
Processing section "[public]"
Loaded services file OK.
Server role: ROLE_STANDALONE
[global]
    map to guest = Bad Password
    private dir = /clusterdata/ctdb
    max protocol = SMB2
    use mmap = No
    clustering = Yes
    fileid:mapping = fsname
    idmap config * : backend = tdb2
    ea support = Yes

[public]
    comment = public share
    path = /clusterdata/public
    read only = No
    guest only = Yes
    guest ok = Yes


[root@smb2 ~]# cat /etc/sysconfig/ctdb
 CTDB_RECOVERY_LOCK="/clusterdata/ctdb.lock"
 CTDB_PUBLIC_INTERFACE=eth0
 CTDB_PUBLIC_ADDRESSES=/etc/ctdb/public_addresses
 CTDB_MANAGES_SAMBA=yes
 ulimit -n 10000
 CTDB_NODES=/etc/ctdb/nodes
 CTDB_LOGFILE=/var/log/log.ctdb
 CTDB_DEBUGLEVEL=2
 CTDB_PUBLIC_NETWORK="192.168.1.0/24"
 CTDB_PUBLIC_GATEWAY="192.168.1.1"

Jan 14 19:01:12 smb2 smbd[17637]: [2014/01/14 19:01:12.908248,  0] locking/locking.c:887(share_mode_lock_destructor)
Jan 14 19:01:12 smb2 smbd[17637]:   delete_rec returned NT_STATUS_UNSUCCESSFUL
Jan 14 19:01:12 smb2 smbd[17637]: [2014/01/14 19:01:12.908417,  0] lib/util.c:1117(smb_panic)
Jan 14 19:01:12 smb2 smbd[17637]:   PANIC (pid 17637): could not delete share entry: NT_STATUS_UNSUCCESSFUL

[root@smb1 ~]# rpm -qa | grep samba
samba-winbind-3.6.9-167.el6_5.x86_64
samba-3.6.9-167.el6_5.x86_64
samba-common-3.6.9-167.el6_5.x86_64
samba-winbind-clients-3.6.9-167.el6_5.x86_64