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GCS>Sun Microsystems>Storage - Disk>Network Attached Storage
 

Symptoms:

• Need to check TCP/IP config on NAS 5000

Purpose/scope:

This document describes how to use the Sun StorageTek 5000 Series NAS built-in utilites to check for and resolve TCP/IP configuration issues.

The primary tool to investigate network connectivity problems is the netstat command. This command is available from the CLI. Simply type netstat at the CLI and a list of all network interfaces and routes displays, along with some useful statistics.

Here is an example of the output:

NAS > netstat

Name   Mtu   Netmask         Address         Ipackets Ierr Opackets Oerr  Coll
lo0     1536 255.0.0.0       127.0.0.1       15029886    0 15029886    0     0
emc1    1500 255.255.255.0   10.10.10.1        459032    0   447821    0     0
emc2    1500 255.255.255.0   192.168.77.2    10058743    0 22249922    0     0
emc3    1500 255.255.255.0   192.168.77.3    12158424    0       15    0     0
emc4    1500 255.255.255.0   192.168.88.2           0    0     3755    0     0
emf5    1500 255.255.255.128 192.168.99.2     8899843    0  7687683    0 41292

Netmask         Destination     Gateway         Interf Flags    Refs Use
0.0.0.0         0.0.0.0         192.168.77.254  emc2   ug       52   11744053
255.255.255.0   10.10.10.0      10.10.10.2      emc1   uc       0    9010329
255.255.255.0   192.168.77.0    192.168.77.2    emc2   uc       98   42741934
255.255.255.255 127.0.0.1       127.0.0.1       lo0    uh       12   15029886
255.255.255.0   192.168.88.0    192.168.88.2    emc4   uc       5    345
255.255.255.128 192.168.99.0    192.168.99.99   emf5   uc       0    0

These two tables display the following information:

Table 1: Network addresses and packet statistics:

• The adapter lo0 is the loopback device and does not represent a physical adapter.

• The adapters named "emc" are the on-board copper Gigabit interfaces. In a cluster system, depicted above, emc1 will always be the head-to-head heartbeat interface, with an address of 10.10.10.1 or 10.10.10.2. An "emf" interface name indicates an optional fibre Gigabit interface.

• MTU: This should be left at the default setting. Ensure that this is not set higher than 1536, as the StorageTek[TM] 5000 Series NAS does not support Jumbo Frames at this time.

• Netmask & Address: These should match settings on the network. For the example above, a client on the same subnet should have the same subnet mask (255.255.255.0 for 192.168.77.x and 255.255.255.128 for 192.168.77.x).

• Ipackets & Opackets: Ipackets (in) is the total number of packets received, Opackets (out) is the total number of packets sent. These statistics can be used to determine if a particular interface is successfully sending or receiving, and can detect some configuration problems. In the example above, both emc2 and emc3 have been configured with separate addresses on the same subnet, causing all outbound traffic to be sent via emc2. (See table 2 below for why this happens.) Also in the example, emc4 is not receiving packets.

• Ierr, Oerr, & Coll: These are all packet errors, and should normally be at zero on a switched network. An incrementing number here can indicate a bad NIC or cable, a malfunctioning client, or in the case of the ?coll? statistic, an incorrect speed and duplex setting.

Table 2: Routing Table:

• The route 0.0.0.0 is the default route. All packets that are destined for a subnet that is not directly connected to the NAS are routed to the default gateway, which should be a router equipped to handle these requests. In the example above 10.10.10.x, 192.168.77.x, 88.x and 99.x are directly connected.

• Netmask: As noted in the first table. An incorrect netmask usually results in some clients being unable to ping or connect.

• Destination & Gateway: These two addresses work together. Packets intended for the destination network are sent to the gateway. Note that there is a destination required for even the locally attached subnets. (192.168.77.0,, 88.0, and 99.0 in the example) This is the reason that it is inefficient to configure multiple adapters on the same subnet without bonding.

• Interf: This is the name of the internal interface used to send packets for a particular route.

• Flags: These are as follows, u - usable, h - host, g -gateway, c - system, d - dynamic, m - modified. The usable flag will almost always be present, though if it is not, there is an IP misconfiguration somewhere. The ones to watch for on this list are "d" and "m". These are an indication that the route you have configured has been modified by another router. This is very rare, but when it occurs, a message will be logged to the NAS system log so that you can either choose to use the new route, or fix the route on the offending router. These messages are sent via the ICMP protocol.

• Refs: Generally not useful for troubleshooting.

• Use: This statistic can be used much like the Ipackets/Opackets statistic in the first table. This statistic indicates how many times a route has been used. If you defined a route for a specific purpose, such as mirroring, and this counter is not incrementing, then the route was most likely not defined correctly.

Also, when troubleshooting connectivity issues, don't forget to check the basics. Try another client on the same subnet, try another cable, and try another switch port for both client and the NAS.

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