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Nslookup resolves address but ping is unable to resolve hostname on Unix server

Andrew Lin — Wed, 17 Nov 2010 14:42:58 +0000

I came across this issue on my newly built Solaris 10 server. I was able to ping a remote machine by Ip address, but not by its hostname. This indicated that I had the correct route and gateway. Using nslookup and dig I verified that the DNS servers were resolving the hostname to IP address. I confirmed that the file /etc/resolv.conf had the correct syntax for search domain-name.com.

Here is what my /etc/resolv.conf looks like, the two DNS servers are defined correctly as it the search domain.
domain andrewlin.com
namesserver 10.10.10.11
namesserver 10.10.11.13
search andrewlin.com
The gateway was defined in /etc/defaultrouter.
10.10.0.1
It seems that ping did not know how to resolve an address. I was also not able to surf the internet with the Firefox browser in the Sun Java Desktop System for Soalris. All symptoms indicated that the nsswitch.conf did not have the correct environment defined. The /etc/nsswitch.conf file defines which services are to used to retrieve information such as hostnames, password files, and group files. So in this case for the command ping and firefox which wants to resolve and address, it will check the nsswitch.conf file to see what services to use.

Below are the lines I changed in /etc/nsswitch.conf, by adding dns to the end of each lines.
hosts: files dns
ipnodes: files dns
I am now able to ping and surf the internet without any issues.

Booting up Solaris 10 from a SAN replicated LUN on a different Sun SPARC server

Andrew Lin — Fri, 09 Jul 2010 20:23:40 +0000

The quickest way to recover from a total disaster is to have some sort of replication implemented. There are two different methods of real-time replication, hardware and software. My experiences with software replication such as Symantec Veritas Volume replicator for AIX was not pleasing. It required constant maintenance and troubleshooting. The best is hardware replication if you can afford it. A lot of organizations pick software replication as it generally cost a lot less up front, but the cost of maintenance eventually adds up.

I will explain how to recover a Solaris 10 server from hardware replicated SAN disk. It took me sometime to figure out how to boot up from the replicated SAN LUN (disk), and many more hours to understand why the steps I applied works.

In this example I have a SUN SPARC M3000 server with two Qlogic fiber channel cards (HBA) installed in the PCI solts. The HBAs were already configured to connect to the SAN disk (LUN). This LUN contained the replicated copy of a production Slaris 10 server. The production server had two ZFS pool residing in a single LUN.

Using the Solaris 10 installation CD boot up the Sparc server into single user mode.

boot cdrom -s

The first thing you need to do is to see if the HBAs are working. The connected status indictes that communication between the server and switch is working. There are two HBAs installed for redundancy, both connected to the same LUN.

# luxadm -e port
/devices/pci@0,600000/pci@0/pci@8/SUNW,qlc@0/fp@0,0:devctl CONNECTED
/devices/pci@1,700000/pci@0/pci@0/SUNW,qlc@0/fp@0,0:devctl CONNECTED

Now you need to find out if the SAN disk is visible from the server. Even though both HBAs are connected to the same SAN disk, you will see two separate SAN disks in the results below. It just means there are two paths to the SAN.

# luxadm probe
No Network Array enclosures found in /dev/es

Found Fibre Channel device(s):
Node WWN:50060e80058c7b10 Device Type:Disk device
Logical Path:/dev/rdsk/c1t50060E80058C7B10d1s2
Node WWN:50060e80058c7b00 Device Type:Disk device
Logical Path:/dev/rdsk/c2t50060E80058C7B00d1s2

In the above example the first LUN is c1t50060E80058C7B10d1s2. This is the logical device name which is a symbolic link to the physical device name stored in the /devices directory. Logical device names contain the controller number(c2), target number (t50060E80058C7B10), disk number (d1), and slice number (s2).

The next step is to find out how the disk is partitioned, the format command will give you that information. You need this information to understand how to boot up the disk.

# format
Searching for disks…done

AVAILABLE DISK SELECTIONS:
0. c1t50060E80058C7B10d1 1066>/pci@0,600000/pci@0/pci@8/SUNW,qlc@0/fp@0,0/ssd@w50060e80058c7b10,1

1. c2t50060E80058C7B00d1 1066>/pci@1,700000/pci@0/pci@0/SUNW,qlc@0/fp@0,0/ssd@w50060e80058c7b00,1

Select the first disk 0.

Specify disk (enter its number): 0
selecting c1t50060E80058C7B10d1
[disk formatted]

FORMAT MENU:
disk – select a disk
type – select (define) a disk type
partition – select (define) a partition table
current – describe the current disk
format – format and analyze the disk
repair – repair a defective sector
label – write label to the disk
analyze – surface analysis
defect – defect list management
backup – search for backup labels
verify – read and display labels
save – save new disk/partition definitions
inquiry – show vendor, product and revision
volname – set 8-character volume name
! – execute , then return
quit

Display the labels and slices (partitions). In Solaris each slice is treated as a separate physical disk. In the below example you can tell that the disk is labeled as VTOC (Volume Table of Contents) because you can see the cylinders. VTOC is also known as SMI label. If the disk was labeled with EFI (Extensible Firmware Interface), then you would see sectors instead of cylinders. Partition 0 (slice 0) holds the operating system files, the boot disk. Please note that you cannot boot from a disk with EFI label. Slice 2 is the entire physical disk because it contains all cylinders, 0 – 65532.

format> verify

Primary label contents:

Volume name = <
ascii name =
pcyl = 65535
ncyl = 65533
acyl = 2
nhead = 15
nsect = 1066
Part Tag Flag Cylinders Size Blocks
0 root wm 0 – 3356 25.60GB (3357/0/0) 53678430
1 unassigned wm 0 0 (0/0/0) 0
2 backup wm 0 – 65532 499.66GB (65533/0/0) 1047872670
3 unassigned wm 0 0 (0/0/0) 0
4 unassigned wm 0 0 (0/0/0) 0
5 unassigned wm 0 0 (0/0/0) 0
6 unassigned wm 0 0 (0/0/0) 0
7 unassigned wm 3357 – 65532 474.07GB (62176/0/0) 994194240

Here is what we know so far, we know that the disk name is c1t50060E80058C7B10d1. Slice 0 on this disk contains the boot files. The physical path for this disk is /pci@0,600000/pci@0/pci@8/SUNW,qlc@0/fp@0,0/ssd@w50060e80058c7b10,1. Now we need to find out the physical path for Slice 0.

I know that the disk contains ZFS filesystems because it is a replica of the production disk. When a ZFS filesystem is moved to a different SPARC server it must first be imported because the hostid is different.

List the ZFS pool contained on the disk using the zpool import command. There are two ZFS pools in the below example, epool and rpool. Take a note of the status and action.

# zpool import
pool: epool
id: 16865366839830765202
state: ONLINE
status: The pool was last accessed by another system.
action: The pool can be imported using its name or numeric identifier and the ‘-f’ flag.
see: http://www.sun.com/msg/ZFS-8000-EY
config:

epool ONLINE
c2t50060E80058C7B00d1s7 ONLINE

pool: rpool
id: 10594898920105832331
state: ONLINE
status: The pool was last accessed by another system.
action: The pool can be imported using its name or numeric identifier and the ‘-f’ flag.
see: http://www.sun.com/msg/ZFS-8000-EY
config:

rpool ONLINE
c2t50060E80058C7B00d1s0 ONLINE

Import the pool with the zpool import command. The options -a will import all the ZFS pools it can find, the -f option will force the import. If you do not specify the force option, then the import may fail with the error “cannot import ‘rpool’: pool may be in use from other system, it was last accessed by server name (hostid: 123456)”. Ignore the error message about failed to create mountpoint.

# zpool import -af
cannot mount ‘/epool’: failed to create mountpoint
cannot mount ‘/rpool’: failed to create mountpoint

List the imported ZFS pools.

# zpool list
NAME SIZE USED AVAIL CAP HEALTH ALTROOT
epool 472G 260G 212G 55% ONLINE -
rpool 25.5G 5.75G 19.8G 22% ONLINE -

List the ZFS filesystems. In the example below notice the mountpoint / is mounted on the zfs filesystem rpool/ROOT/zfsboot. This is the boot partition, it resides in rpool.

# zfs list
NAME USED AVAIL REFER MOUNTPOINT
epool 260G 205G 21K /epool
rpool 7.74G 17.4G 99K /rpool
rpool/ROOT 4.74G 17.4G 21K legacy
rpool/ROOT/zfsboot 4.74G 17.4G 4.48G /
rpool/ROOT/zfsboot/var 139M 17.4G 105M /var
rpool/dump 1.00G 17.4G 1.00G -
rpool/swap 2.00G 19.4G 16K -

Change the mountpoint for rpoo/ROOT/zfsboot to /mnt so you can mount it to read the contents.

# zfs set mountpoint=/mnt rpool/ROOT/zfsboot

Confirm that the mountpoint was changed.

# zfs list
NAME USED AVAIL REFER MOUNTPOINT
epool 260G 205G 21K /epool
rpool 7.74G 17.4G 99K /rpool
rpool/ROOT 4.74G 17.4G 21K legacy
rpool/ROOT/zfsboot 4.74G 17.4G 4.48G /mnt
rpool/ROOT/zfsboot/var 139M 17.4G 105M /mnt/var
rpool/dump 1.00G 17.4G 1.00G -
rpool/swap 2.00G 19.4G 16K -

Now mount rpool/ROOT/zfsboot.

# zfs mount rpool/ROOT/zfsboot

List the logical disks.

# cd /dev/dsk
# ls
c1t50060E80058C7B10d1s0 c2t50060E80058C7B00d1s0
c1t50060E80058C7B10d1s1 c2t50060E80058C7B00d1s1
c1t50060E80058C7B10d1s2 c2t50060E80058C7B00d1s2
c1t50060E80058C7B10d1s3 c2t50060E80058C7B00d1s3
c1t50060E80058C7B10d1s4 c2t50060E80058C7B00d1s4
c1t50060E80058C7B10d1s5 c2t50060E80058C7B00d1s5
c1t50060E80058C7B10d1s6 c2t50060E80058C7B00d1s6
c1t50060E80058C7B10d1s7 c2t50060E80058C7B00d1s7

As stated earlier the physical path for the disk we are looking for is /pci@0,600000/pci@0/pci@8/SUNW,qlc@0/fp@0,0/ssd@w50060e80058c7b10,1. The boot slice is 0. We can derive from the physical path that the disk name is 50060e80058c7b10. We also know from the output of the format command that the physical disk 50060e80058c7b10 maps to the logical disk c1t50060E80058C7B10d1. Therefore we can derive that the logical boot disk is c1t50060E80058C7B10d1s0.

Now find out what physical path c1t50060E80058C7B10d1s0 is a symbolic link for and that is your complete boot path. In the below example the boot path starts at the first slash (/) right after /devices. It is /pci@0,600000/pci@0/pci@8/SUNW,qlc@0/fp@0,0/ssd@w50060e80058c7b10,1:a. You need to replace ssd@ with disk@ when entering the path into EEPROM.

# ls -l c1t50060E80058C7B10d1s0
lrwxrwxrwx 1 root root 82 Jul 5 10:21 c1t50060E80058C7B10d1s0 ->
../../devices/pci@0,600000/pci@0/pci@8/SUNW,qlc@0/fp@0,0/ssd@w50060e80058c7b10,1:a

If you have more than one ZFS pool the non root pool may not get mounted upon booting up the server, as in this example. You may get the below error.

SUNW-MSG-ID: ZFS-8000-D3, TYPE: Fault, VER: 1, SEVERITY: Major
EVENT-TIME: Mon Jul 5 11:54:14 EDT 2010
PLATFORM: SUNW,SPARC-Enterprise, CSN: PX654321, HOSTNAME: Andrew-Lin
SOURCE: zfs-diagnosis, REV: 1.0
EVENT-ID: 33e5a9f1-49ac-6ebc-f2a9-dff25dea6b86
DESC: A ZFS device failed. Refer to http://sun.com/msg/ZFS-8000-D3 for more information.
AUTO-RESPONSE: No automated response will occur.
IMPACT: Fault tolerance of the pool may be compromised.
REC-ACTION: Run ‘zpool status -x’ and replace the bad device.

http://sun.com/msg/ZFS-8000-D3fameserverq9{root}: zpool status -x
pool: epool
state: UNAVAIL
status: One or more devices could not be opened. There are insufficient
replicas for the pool to continue functioning.
action: Attach the missing device and online it using ‘zpool online’.
see: http://www.sun.com/msg/ZFS-8000-3C
scrub: none requested
config:

NAME STATE READ WRITE CKSUM
epool UNAVAIL 0 0 0 insufficient replicas
c3t60060E8005652C000000652C00002100d0s7 UNAVAIL 0 0 0 cannot open

The above error is caused by the zpool.cache file. This file contains the old paths of the disks from the previous server. The default behavior of Solaris 10 is to read the path from the zpool.cache file to speed up the boot sequence. You should delete this file and the system will recreate a fresh one during the boot up sequence.

Below are the steps to rename the zpool.cache file.

# cd /mnt/etc/zfs
# ls
zpool.cache
# mv zpool.cache zpool.cache.old

Now you need to reverse the changed you applied to the mountpoint earlier. Make sure that you change directory out of /mnt to /, otherwise the set mountpoint command will fail with the error device busy. Ignore the cannot mount ‘/’: directory is not empty message.

# zfs set mountpoint=/ rpool/ROOT/zfsboot
cannot mount ‘/’: directory is not empty
property may be set but unable to remount filesystem

Confirm that the mount points were changed.

# zfs list
NAME USED AVAIL REFER MOUNTPOINT
epool 260G 205G 21K /epool
rpool 7.74G 17.4G 99K /rpool
rpool/ROOT 4.74G 17.4G 21K legacy
rpool/ROOT/zfsboot 4.74G 17.4G 4.48G /
rpool/ROOT/zfsboot/var 139M 17.4G 105M /var
rpool/dump 1.00G 17.4G 1.00G -
rpool/swap 2.00G 19.4G 16K -

Shutdown the server.

# init 0

Now set the boot device in EEPROM.

setenv boot-device /pci@0,600000/pci@0/pci@8/SUNW,qlc@0/fp@0,0/disk@w50060e80058c7b10,1:a

The server is ready to be booted with the boot command.

{0} ok boot

How to change the IP address in Solaris 10

Andrew Lin — Thu, 25 Feb 2010 16:17:02 +0000

Here is a list of files that you need to edit when changing the IP address of an interface in Solaris 10.
/etc/hosts
/etc/hostname.interface-name
/etc/nodename
/etc/defaultrouter
/etc/resolv.conf
/etc/netmasks

Add the ip address and server name to the host file.

vi /etc/hosts
10.0.0.10 server-name

Select the interface you want, your server may have more than one network interfaces.

vi /etc/hostname.bge0
10.0.0.10 netmask 255.255.255.0

Change the node name

vi /etc/nodename
server-name

Add the gateway ip address

vi /etc/defaultrouter
10.0.0.1

Add the DNS servers ip addresses

vi /etc/resolv.conf
nameserver 168.20.0.10
nameserver 168.20.10.22

Add the network address

vi /etc/netmasks
10.0.0.0 255.255.255.0

Now reboot the server.

How to create a virtual disk with the Dell OpenManage Server Admnistrator.

Andrew Lin — Thu, 30 Apr 2009 16:20:03 +0000

Open the Dell OpenManage Server Administrator

Click on System – Storage – PERC 5/E Adapter (PCI Slot 1) – Connector 0 (RAID) – Enclosure – Physical Disks.

This will display all the Disk Drives in the right window.

Under the column Available RAID DISK Space, you should be able to determine if there is any unused disk. Make a note of the name of the disks that are avaiable, this would be under the column Name. Such as “Physical Disk 0.0.0″ and “Physical DISK 0.0.1″. You will need to this information when creating the RAID volume.

Go to Click on System – Storage – PERC 5/E Adapter (PCI Slot 1) – Connector 0 (RAID) – Virtual Disks. On the right screen you should see any existing virtual disks.

Click on Go To Create Virtual Disk Wizard, then click on Go To Advanced Wizard. You will be presented with the option to create Raid 0, Raid 1, Raid 5, Raid 10 and Raid 50. The options may differ depending on the firmware and type of PERC controller.

In this case I want to create a RAID 5 volume, which is striping with distributed parity. You need a minumum of 3 hard disks for Raid 5. The storage size equal to one disk is used for parity. So if you have 3 disks then the usable space is equal to the total of 2 disks.

Slect Raid 5 and click on Continue. This will display only the physical disks that are avaiable. Check all the Physical Disks that you wish to add to your virtual Disk, then click on Continue.

You can now give the virtual disk an optional name. Leave the defaults and click on Continue.

When creating virtual disk that is larger than 2 TB in size, you will be prompted with a warning message. “Please verify that your operating system, including any updates or modifications, supports a virtual disk of this size. Do you want to proceed?”. Click on OK to continue.

You will now be presented with the configuration summary. Click on Finish.

The new virtual disk should now appear in the list. Note the Device Name of the new virtual disk you just created, e.g. Windows Disk 2. You will need this information when configuring the new virtual disk in Windows Disk Management MMC. Under the progress column you will see the status of the new disk volume, this may take many hours to complete if the volume is many terra bytes large.

TCP ports opened on firewall for Dell Remote Access Card – DRAC.

Andrew Lin — Tue, 28 Apr 2009 16:13:20 +0000

The Dell Remote Access Card (DRAC) communicates via the following ports:

22 Secure Shell, SSH
23 Telnet
80 http
443 https
161 SNMP
3668 Virtual Media Server
5900 Console Redirection
5901 Console Redirection

If you have a firewall in between you and the server, ensure that you have the above ports opened.

How to find file that contains a specific word in Linux and Unix.

Andrew Lin — Fri, 24 Apr 2009 02:22:55 +0000

The find and grep command is very handy when searching for files that contains a specific word. Both the find and grep commands are universal in Linux and Unix and the syntax is very similar.

Below is an example.

find /home/andrew -type f -exec grep -H ‘networks’ {} \;

This will display all files in the directory /home/andrew that contains the word networks abd output it to screen.

Here is another example using the grep command alone.

grep -r “networks” /home/andrew

How to mount a volume with a different mount point in Aix ?

Andrew Lin — Fri, 29 Feb 2008 03:54:10 +0000

I ran across a situation where my volume was running low on free disk space. In order to prevent my application from crashing, I had to either expand the volume or move the application files to a larger volume. Well, in this case the volume was created with Veritas and I wanted to move the files off to a Aix natively created volume. There were some pretty good business reasons for not expanding the Veeritas volume, one of them being the lack of good support.

Well here is how I did it. First create a new volume and file system, in this case the new volume was mounted as /new-vol. I then backed up all files in the old Veritas volume to tape, let’s say the volume is /old-vol. To back this up to tape (/dev/rmt0) I issued the command ‘tar – cvf /dev/rmt0 /old-vol’, notice I used absolute path and not relative path. You can use either absolute or relative path, for relative simply put a period in front, e.g. ‘tar -cvf /dev/rmt0 ./old-vol’. The period means current directory, so make sure you have changed directory to the proper path, before issuing the tar command.

To rename the mount point, first unmount the volumes. e.g. umount /old-vol and unmount /new-vol. If you get the error that the resource is busy and the volume cannot be unmounted. Then you will need to stop the process that is running. To find out what process was using the /old-vol, first find out what volume is associated with /old-vol. You can do this by issuing the command ‘mount’, and look for the volume name next to the mount point. Then issue the command fuser -c ‘volume name’, this will display any running process. Alternatively the command ‘listuser’, which will display all users currently logged in. The command ‘kill -9 process#’ will stop the running process.

Now edit the file /etc/filesystems and find the line ‘old-vol ‘, and replace that with ‘old-vol-bak’. Also change ‘new-vol’ to ‘old-vol’. Go to the / directory and delete the directory new-vol, ‘rm -r new-vol’, this will remove the directory and all files inside it. Create a directory old-vol-bak, ‘mkdir old-vol-bak’. You should be able to mount the volumes now with these commands, ‘mount /old-vol’ and ‘mount /old-vol-bak’.

Now restore the files from tape with the tar command.

Â tar -xvf /dev/rmt0 /old-vol

This will restore all files under /old-vol.

Sendmail-largeboxes.conf displays warning for large mailboxes

Andrew Lin — Mon, 05 Nov 2007 15:12:13 +0000

The sendmail-largeboxes.cof file is used to display warnings for large mailboxes.Â The default configuration is hard coded to consider 40MB+ as large.Â Users will receive email warnings that they have exceeded the 40MB mailbox size.Â You can change the default 40MB to a different value.Â On my Fedora Core 4 installation the file is located in /usr/share/logwatch/default.conf/services/sendmail-largebooxes.conf.Â Â Â The variable to change is $sendmail_largeboxes_size = 40MB.