Re: [Moosefs-users] nfs export of mfs mount point

[Jun C. P. <jun...@gm...>]

For those who are wondering how to export an MFS mount point as an NFS
mount point, I would like share my experience that uses a user space
NFS (unfs). Basically, I found a simple workaround with performance
degradation as expected (the use of NFS inherently hurts performance,
anyway).

Environment:
* CentOS 5.5
* unfs3-0.9.22
* mfs-1.6.15-2
* unfs server on 10.1.2.22

On user space NFS server:
# wget ftp://ftp.pbone.net/mirror/ftp.pramberger.at/systems/linux/contrib/rhel5/i386/unfs3-0.9.22-1.el5.pp.i386.rpm
# rpm -Uhv unfs3-0.9.22-1.el5.pp.i386.rpm
# cat /etc/exports (assuming 10.* private ip)
   /mnt/mfs 10.0.0.0/255.0.0.0(rw,no_root_squash)
# df | grep mfs
   mfs#10.1.2.22:9421   13020730816 428096384 12592634432   4% /mnt/mfs
# service nfs stop (if running)
# rpc.mountd
# portmap
# unfsd (if you want to debug, use -d)
# exportfs -a -v (if you want to add more exports)

On NFS client:
# cat /etc/fstab |grep mynfs (/mnt/mfs is an MFS mount point on the server)
10.1.2.22:/mnt/mfs /mnt/mynfs nfs rw,proto=tcp,nolock 0 0
# mount /mnt/mynfs

If you have iptables running, the following iptables rules need to be
added to have portmap and unfsd get along with firewall.

# PASS ICMP TYPE 3 PACKETS, INPUT AND OUTPUT
-A INPUT  -p icmp -m icmp --icmp-type 3 -j ACCEPT
-A OUTPUT  -p icmp -m icmp --icmp-type 3 -j ACCEPT

# PASS PORTMAP AT 111, INPUT AND OUTPUT, TCP AND UDP
-A INPUT -p tcp -m tcp --dport 111 -j ACCEPT
-A INPUT -p udp -m udp --dport 111 -j ACCEPT
-A OUTPUT -p tcp -m tcp --sport 111 -j ACCEPT
-A OUTPUT -p udp -m udp --sport 111 -j ACCEPT

# PASS NFS AT 2049, INPUT AND OUTPUT, TCP AND UDP
-A INPUT -p tcp -m tcp --dport 2049 -j ACCEPT
-A INPUT -p udp -m udp --dport 2049 -j ACCEPT
-A OUTPUT -p tcp -m tcp --sport 2049 -j ACCEPT
-A OUTPUT -p udp -m udp --sport 2049 -j ACCEPT

I hope this can help for anyone who needs it.

-Jun

On Thu, Dec 23, 2010 at 2:25 PM, Jun Cheol Park
<jun...@gm...> wrote:
> Hi,
>
> Using nfs (v4 on CentOS 5.5) on top of mfs is definitely silly.
> However, some applications that I plan to use can run only with nfs,
> so I tried to export mfs mount point as an nfs export. For easiness,
> right now I am not using any iptables rules on any node.
>
> On the nfs server (10.1.2.22, at the same time, as a mfs client):
>
> # cat /etc/exports
> /mnt/mfs 10.*(rw,no_root_squash)
>
> # df | grep mfs
> mfs#10.1.2.22:9421 on /mnt/mfs type fuse (rw,allow_other,default_permissions)
>
> On the nfs client (10.1.2.24):
>
> I got the following error.
>
> # mount -t nfs 10.1.2.22:/mnt/mfs /mnt/nfs_mfs/
> mount: 10.1.2.22:/mnt/mfs failed, reason given by server: Permission denied
>
> # tail /var/log/messages
> Dec 23 14:23:23 host1a mountd[17279]: authenticated mount request from
> 10.1.2.24:805 for /mnt/mfs (/mnt/mfs)
> Dec 23 14:23:23 host1a mountd[17279]: Cannot export /mnt/mfs, possibly
> unsupported filesystem or fsid= required
>
> Is there anyone who knows a workaround?
>
> Thanks,
>
> -Jun
>