Dell Unity: NFS hosts utilizing Netgroup are unable to connect to NFS Share. (Dell Correctable)

Summary: NFS hosts are not able to connect to Unity NFS Shares via 'Netgroup', however, NFS is working when using explicit Unity NAS Server IP address, or hostname without issue. When the same hosts attempt to connect to the Unity NFS Share via a 'netgroup', this results in server not responding : RPC: Timed out and loss of access to the NFS Share ...

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Symptoms

Implemented netgroups after upgrading Unity to Unity Version:    4.0.1.8404134

NFS Host unable to access Unity NFS Shares via 'netgroups'.  Same NFS Host is able to directly attach to the Unity NFS Shares via Unity NAS Server IP Address, or via Unity NAS Server 'hostname', however, if same NFS Host attempts to attach to Unity NAS Server NFS share via a 'netgroup', this results in a loss of access to the Unity NFS Share.

An Alert appears on the Unity Unisphere GUI, in the 'alerts' section: "The Network Information Service (NIS) configured for the NAS server was unable to provide user mapping information and is not responding. Check the availability of the NIS server, and ensure that the domain name and addresses used for the server are accurate."


Similar alert can be viewed and observed via Unity CLI :

21:08:58 root@(none) spa:/home/service> uemcli /event/alert/hist show
Storage system address: 127.0.0.1
Storage system port: 443
HTTPS connection

1:    ID           = alert_804
      Time         = 2016-09-26 21:07:59.088
      Message      = NAS server n125d061: There is no NIS server on-line for the domain nb-engr.
      Description  = "The Network Information Service (NIS) configured for the NAS server was unable to provide user mapping information and is not responding. Check the availability of the NIS server, and ensure that the domain name and addresses used for the server are accurate."
      Severity     = error
      Acknowledged = no

2:    ID           = alert_803
      Time         = 2016-09-26 21:07:44.102
      Message      = NAS server n125d061: There is no NIS server on-line for the domain nb-engr.
      Description  = "The Network Information Service (NIS) configured for the NAS server was unable to provide user mapping information and is not responding. Check the availability of the NIS server, and ensure that the domain name and addresses used for the server are accurate."
      Severity     = error
      Acknowledged = no

3:    ID           = alert_802
      Time         = 2016-09-26 21:07:29.174
      Message      = NAS server n125d061: There is no NIS server on-line for the domain nb-engr.
      Description  = "The Network Information Service (NIS) configured for the NAS server was unable to provide user mapping information and is not responding. Check the availability of the NIS server, and ensure that the domain name and addresses used for the server are accurate."
      Severity     = error
      Acknowledged = no


A check on whether rpc.d is running on the Unity NAS Server, indicates, that rpc.mountd, rpc,nfsd, and rpc.portmapper are running.

root@spa:/cores/service>/sbin/rpcinfo -p 10.#.#.##
   program vers proto   port  service
    100000    4   udp    111  portmapper
    100000    3   udp    111  portmapper
    100000    2   udp    111  portmapper
    100000    4   tcp    111  portmapper
    100000    3   tcp    111  portmapper
    100000    2   tcp    111  portmapper
    100003    4   tcp   2049  nfs
    100005    1   udp   1234  mountd
    100005    2   udp   1234  mountd
    100005    3   udp   1234  mountd
    100005    1   tcp   1234  mountd
    100005    2   tcp   1234  mountd
    100005    3   tcp   1234  mountd
    100003    3   tcp   2049  nfs
    100021    4   tcp   4001  nlockmgr
    100021    1   tcp   4001  nlockmgr
    100021    2   tcp   4001  nlockmgr
    100021    3   tcp   4001  nlockmgr
    100024    1   tcp   4000  status
    100003    3   udp   2049  nfs
    100021    4   udp   4001  nlockmgr
    100021    1   udp   4001  nlockmgr
    100021    2   udp   4001  nlockmgr
    100021    3   udp   4001  nlockmgr
    100024    1   udp   4000  status
 536870914    2   tcp   4658
 536870914    2   udp   4658
 824395111    1   udp  39850
 824395111    1   tcp  50600
    102660    1   tcp  37185
    102660    1   udp  52008


Similary checking on the status of 'rpc.d' from the NFS Host, pointing to the Unity NAS Server, also indicates that
rpc.mountd, rpc,nfsd, and rpc.portmapper are running on the Unity NAS Server

bash-2.03# rpcinfo -p 10.#.#.#0
   program vers proto   port  service
    100000    4   udp    111  portmapper
    100000    3   udp    111  portmapper
    100000    2   udp    111  portmapper
    100000    4   tcp    111  portmapper
    100000    3   tcp    111  portmapper
    100000    2   tcp    111  portmapper
    100003    4   tcp   2049  nfs
    100005    1   udp   1234  mountd
    100005    2   udp   1234  mountd
    100005    3   udp   1234  mountd
    100005    1   tcp   1234  mountd
    100005    2   tcp   1234  mountd
    100005    3   tcp   1234  mountd
    100003    3   tcp   2049  nfs
    100021    4   tcp   4001  nlockmgr
    100021    1   tcp   4001  nlockmgr
    100021    2   tcp   4001  nlockmgr
    100021    3   tcp   4001  nlockmgr
    100024    1   tcp   4000  status
    100003    3   udp   2049  nfs
    100021    4   udp   4001  nlockmgr
    100021    1   udp   4001  nlockmgr
    100021    2   udp   4001  nlockmgr
    100021    3   udp   4001  nlockmgr
    100024    1   udp   4000  status
 536870914    2   tcp   4658
 536870914    2   udp   4658
 824395111    1   udp  39850
 824395111    1   tcp  50600
    102660    1   tcp  37185
    102660    1   udp  52008 


NFS Host is able to successfully attach (mount) to the Unity NAS Server NFS Share via the Unity's IP Address and via Unity NAS Server hostname, but after user attempts to connect the NFS Host to the Unity NAS Share via 'netgroup' it fails with: 


bash-2.03# showmount -e  10.#.#.#0
export list for 10.#.#.#0:
/steventestfs    (everyone)
stevetestshare (everyone)
/tejasshare     n#-e###-a##,10.#.#.##1/255.255.255.255,10.#.#.##/255.255.255.255


bash-2.03# mount  10.#.#.#0:/tejasshare /mwtest/
nfs mount: 10.#.#.#0:/tejasshare: server not responding : RPC: Timed out
nfs mount: retrying: /mwtest
nfs mount: 10.#.#.#0:/tejasshare: server not responding : RPC: Timed out

 

Cause

Unity dropping Legal YP MATCH responses in the form of "host.byaddr".  Unity utilizes a strict internal 'firewall' that is dropping network packets.  The Unity NAS Server container, is not allowing datagrams sent by the NIS Server, when the NIS Server uses a different port value for its source port, than the port value it returns in "PORTMAP' requests.  

Unity's default internal firewall policy is to DROP if no rules matches. So, any random ports much match the "-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT" rule.

Resolution

A Unity software fix is currently being developed. Currently being tracked via AR Number 858778. Contact Dell-EMC Technical Support for update on 'code fix'.


In the meantime we have a workaround.  The workaround requires a change of the ip-chains.

connect to the Unity, and inject Root.

add a rule at customer box to accept any udp packet from the NIS servers.  After adding the rule, the NIS should work. This is not really a permanent solution, but a workaround, check on AR number 858778 for software fix.

To add:

iptables -A IN_DATA -p udp -s <ip address of the NIS server> -j ACCEPT

do the above command for each of the NIS Servers IP address, then you can confirm that netgroups work, you can then run the following command to delete.

To Delete:
iptables -D IN_DATA -p udp -s <ip address of the NIS server> -j ACCEPT


example:

   root@spa:/cores/service>iptables -S IN_DATA
   -N IN_DATA
   -A IN_DATA -p tcp -m tcp --dport 445 -j ACCEPT
   ....
   -A IN_DATA -i eve_br0 -p udp -m multiport --dports 22 -j ACCEPT
   -A IN_DATA -s 10.#.#.##/32 -p udp -j ACCEPT
   -A IN_DATA -s 10.#.#.##/32 -p udp -j ACCEPT

 

Affected Products

Dell EMC Unity Family

Products

Dell Unity 300, Dell EMC Unity 300F, Dell EMC Unity 400, Dell EMC Unity 500, Dell EMC Unity 500F, Dell EMC Unity 600, Dell EMC Unity 600F, Dell EMC Unity Family |Dell EMC Unity All Flash, Dell EMC Unity Family
Article Properties
Article Number: 000055193
Article Type: Solution
Last Modified: 17 Feb 2025
Version:  4
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