Tips, Tricks and More for IT System Administrators and Computer Users

How to kill the process running on specific port in Linux

2011-07-21T11:54:00.000-07:00

I would like to stop the process which is running on port 8080 in a Linux server, but I don't know the process that owns it.

'lsof -w -n -i tcp:8080'

or

'fuser -n tcp 8080'

or

'netstat -anp | grep :8080[[:blank:]]'

should show you the process ID.

If there is no (init) script to use to shut down the offending service (since TCP/8080 means proxy) to kill you can by PID 'kill -9 pidnumber'.

How to send email from the Linux command line

2011-07-21T08:02:00.000-07:00

The Linux command line can be very powerful once you know how to use it. You can parse data, monitor processes, and do a lot of other useful and cool things using it. There often comes a need to generate a report and mail it out. It could be as simple a requirement as a notification that the day’s backup went through fine, or did not. I’ll help you get started with sending mails from the Linux command line and in shell scripts. We will also cover sending attachments from the command line. We will begin with the “mail” command.

MAIL

First run a quick test to make sure the “sendmail” application is installed and working correctly. Execute the following command, replacing “you@youremailid.com” with your e-mail address.

# mail -s “Hello world” you@youremailid.com

Hit the return key and you will come to a new line. Enter the text “This is a test from my server”. Follow up the text by hitting the return key again. Then hit the key combination of Control+D to continue. The command prompt will ask you if you want to mark a copy of the mail to any other address, hit Control+D again. Check your mailbox. This command will send out a mail to the email id mentioned with the subject, “Hello world”.

To add content to the body of the mail while running the command you can use the following options. If you want to add text on your own:

# echo “This will go into the body of the mail.”
mail -s “Hello world” you@youremailid.com

And if you want mail to read the content from a file:

# mail -s “Hello world” you@youremailid.com < /home/calvin/application.log

Some other useful options in the mail command are:

-s subject (The subject of the mail)

-c email-address (Mark a copy to this “email-address”, or CC)

-b email-address (Mark a blind carbon copy to this “email-address”, or BCC)

Here’s how you might use these options:

# echo “Welcome to the world of Calvin n Hobbes”
mail -s “Hello world” calvin@cnh.com -c hobbes@cnh.com -b susie.derkins@cnh.com

MUTT

One of major drawbacks of using the mail command is that it does not support the sending of attachments. mutt, on the other hand, does support it. I’ve found this feature particularly useful for scripts that generate non-textual reports or backups which are relatively small in size which I’d like to backup elsewhere. Of course, mutt allows you to do a lot more than just send attachments. It is a much more complete command line mail client than the “mail” command. Right now we’ll just explore the basic stuff we might need often. Here’s how you would attach a file to a mail:

# echo “Sending an attachment.”
mutt -a backup.zip -s “attachment” calvin@cnh.com

This command will send a mail to calvin@cnh.com with the subject (-s) “attachment”, the body text “Sending an attachment.”, containing the attachment (-a) backup.zip. Like with the mail command you can use the “-c” option to mark a copy to another mail id.

SENDING MAIL FROM A SHELL SCRIPT

Now, with the basics covered you can send mails from your shell scripts. Here’s a simple shell script that gives you a reading of the usage of space on your partitions and mails the data to you.

#!/bin/bash

df -h
mail -s “disk space report” calvin@cnh.com

Save these lines in a file on your Linux server and run it. You should receive a mail containing the results of the command. If, however, you need to send more data than just this you will need to write the data to a text file and enter it into the mail body while composing the mail. Here’s and example of a shell script that gets the disk usage as well as the memory usage, writes the data into a temporary file, and then enters it all into the body of the mail being sent out:

#!/bin/bash

df -h > /tmp/mail_report.log

free -m >> /tmp/mail_report.log

mail -s “disk and RAM report” calvin@cnh.com < /tmp/mail_report.log

Now here’s a more complicated problem. You have to take a backup of a few files and mail then out. First the directory to be mailed out is archived. Then it is sent as an email attachment using mutt. Here’s a script to do just that:

#!/bin/bash

tar -zcf /tmp/backup.tar.gz /home/calvin/files

echo
mutt -a /tmp/backup.tar.gz -s “daily backup of data” calvin@cnh.com

The echo at the start of the last line adds a blank into the body of the mail being set out.

This should get you started with sending mails form the Linux command line and from shell scripts. Read up the “man page” for both mail and mutt for more options.

How to export ipod notes to your PC computer for free?

2011-06-23T18:50:00.000-07:00

There are few applications in the market offering this feature, but if you want to do it for free and easily, take note of how to do it:

1) You will need a PC computer with iTunes and Microsoft Outlook. Of course, you also need your ipod and the cable connected to the PC.
2) You must install Microsoft Outlook (not Outlook Express), and set it up as the default email client. You can do it temporarily if you want, and then change it back later to your favorite email client.
This is because itunes uses Microsoft Outlook as the default application to synchronize the Notes.
Go to iTunes, select your ipod under Devices, and from the tabs on top, select Info. In the section "Other" tick the option "Sync notes with: Outlook"
Do it, sync your ipod.
3) You will find all your notes in Outlook, that is the yellow sticky notes icon under "Tasks" on the left menu. Or just use the menu: Go to -> Notes.
You can start copying and pasting the contents of your notes, but if you have many of them, it is a better idea to export them to notepad, however, there is no such functionality in Outlook :(
Don't worry, go to the next step.
4) Open outlook, Alt+F11 to open VBA editor, put the following code in the right blank area, while on the vba editor, click the save button.

Sub exportNotes()
On Error GoTo huboerr
myfolder = "c:\notes\" 'change this to your folder path but folder path has to end with a backlash
Set myNote = Application.GetNamespace("MAPI").GetDefaultFolder(olFolderNotes)
For ibi = 1 To myNote.Items.Count
fname = myNote.Items(ibi).Subject
myNote.Items(ibi).SaveAs myfolder & fname & ".txt", 0

Next
Exit Sub
huboerr:
MsgBox fname
Resume Next

End Sub

Then all you need to do is to change the first line of code to the path of export folder
While in vba editor, when hit F5, all the notes in the notes folder will be exported to the folder you specified, the notes name will be the same as you have in your Outlook notes and in your ipod . You will probably have to edit the note names in Outlook before exporting them, as you may name them using some special characters (*, %, etc.) that are not accepted by Windows...

I hope it saved you some time re-typing the notes in your PC, and some bucks if you were thinking about buying an application for doing that.

Enjoy !

How do I find discovered SAN targets and LUNs on a Linux host with Emulex HBA cards?

2011-06-20T14:36:00.000-07:00

The sys file system (sysfs) provides details on what devices have been discovered.

Change directory to /sys/class/scsi_host. Perform an ls:

[tam@tsdownload scsi_host]$ ls
host0

Each SCSI host adapter and those that look like SCSI host adapters to Linux are assigned a host number by Linux. You may see more than one hostX (where x is a number). In the example above, only one SCSI host bus adapter is found, host0. If there are more than one, perform an ls command on each:

[tam@tsdownload scsi_host]$ ls host0
[tam@tsdownload scsi_host]$ ls host0
board_online lpfc_discovery_min_wait node_name
cmd_per_lun lpfc_discovery_wait_limit nport_evt_cnt
ctlreg lpfc_drvr_version num_discovered_ports
device lpfc_fcp_bind_method option_rom_version
disc_adisc lpfc_fcp_class outfcpio
disc_map lpfc_fdmi_on portfcid
disc_npr lpfc_hba_queue_depth port_name
disc_plogi lpfc_link_speed portnum
disc_prli lpfc_linkup_wait_limit port_type
disc_reglgn lpfc_log_verbose proc_name
disc_unmap lpfc_lun_queue_depth programtype
disc_unused lpfc_max_luns scan
events lpfc_nodev_tmo serialnum
fabric_name lpfc_scan_down sg_tablesize
fwrev lpfc_topology speed
hdw lpfc_use_adisc state
host_busy management_version unchecked_isa_dma
info mbox unique_id
issue_lip modeldesc
lpfc_ack0 modelname

Any items listed with lpfc are Emulex adapters. You can check the model, firmware version, and driver version:

[tam@tsdownload host0]$ cat info
Emulex LP10000 2Gb PCI-X Fibre Channel Adapter on PCI bus 05 device 20 irq 209

[tam@tsdownload host0]$ cat lpfc_drvr_version
Emulex LightPulse Fibre Channel SCSI driver 8.0.16.27

[tam@tsdownload host0]$ cat fwrev
1.91A5 (T2D1.91A5)

Change directory to the host directory and then the device directory:

[tam@tsdownload scsi_host]$ cd host0
{tam@tsdownload host0]$ device
[tam@tsdownload device]$ ls
detach_state power target0:0:0 target0:0:1

Each target and LUN is listed as targetX:Y:Z where:
•X is the bus number
•Y is the target number
•Z is the LUN number.
These are the devices discovered by the host bus adapter and Linux SCSI midlayer.

To determine what type of devices were found, change directory to the targetX:Y:Z directory and then the X:X:X:X directory below it. You can cat the model, vendor, and other files to learn more about the devices:
[tam@tsdownload device]$ cd 0:target0:0:0
[tam@tsdownload target0:0:0]$ cd 0:0:0:0
[tam@tsdownload 0:0:0:0]$ ls
block detach_state dump power rescan scsi_level timeout vendor
delete device_blocked model queue_depth rev state type

[tam@tsdownload 0:0:0:0]$ cat model
ST336854FC

[tam@tsdownload 0:0:0:0]$ cat vendor
SEAGATE

[tam@tsdownload 0:0:0:0]$ cat state
running

The 0:0:0:0 directory represents host bus adapter 0, bus 0, target 0, LUN 0.

Original document (official Emulex web site):
http://www.emulex.com/knowledge/search/viewArticle.jsp?docId=68

Upgrade to Vspere ESX 4.1 failed, ESX host boot stops and drops into Troubleshooting mode.

2011-06-04T10:25:00.000-07:00

Recently, I've got this error whe upgrading an ESX host from version 4.0 to 4.1 upd 01, using the upgrade manager. I was looking to the console, after the ESX host reboot and:

ESX host boot stops at the error: VSD mount/Bin/SH:cant access TTY job control turned off

I was in panic.

Rebooting the host failed, giving me the same error.

I didn't want to re-install the host, because I had some Production Virtual Machines in the local storage, and wanted to solve it quick, as my maintenance window was almost over.

On the ESX console, you see the error:

VSD mount/bin/sh:can't access TTY; job control turned off.

The ESX host does not boot and drops into Troubleshooting (busy box) mode.

Looking into the /var/log/messages file, there was something similar to:

sysboot: Getting '/boot/cosvdmk' parameter from esx.conf

sysboot: COS VMDK Specified in esx.conf: /vmfs/volumes/4b27ec62-93ec3816-0475-00215aaf882a/esxconsole-4b27e9e3-20ee-69d7-ae11-00215aaf882a/esxconsole.vmdk

sysboot: 66.vsd-mount returned critical failure

sysboot: Executing 'chvt 1'

How to solve it:

This issue occurs if an ESX host cannot identify the esxconsole.vmdk file in which the service console resides.

1. Go to the console of the ESX host. After the error message, ESX drops into Troubleshooting (busy box) mode.

2. Find the .vmdk for the service console by running the command:

grep "/boot/cosvmdk" /etc/vmware/esx.conf

The output is similar to:

/boot/cosvmdk = "/

For example:

/boot/cosvmdk = "/vmfs/volumes/4a14d968-88bf7161-700f-00145ef48f76/esxconsole-4a14d906-2f96-7956-7284-00145ef48f74/esxconsole.vmdk"

3. Make note of the and the

4. Verify that the files exist by running the command:

ls -al /vmfs/volumes//

Where and is from the output of step 2.

The output is similar to:

total 7906560

drwxr-xr-x 1 root root 840 May 21 00:45 .

drwxr-xr-t 1 root root 2660 Oct 21 09:10 ..

-rw------- 1 root root 8095006720 Oct 26 15:37 esxconsole-flat.vmdk

-rw------- 1 root root 475 May 21 00:32 esxconsole.vmdk

drwxr-xr-x 1 root root 980 May 21 00:45 logs

5. Ensure that both the esxconsole-flat.vmdk and the esxconsole.vmdk files exist.

In my case, the esxconsole.vmdk file did not exist.

I troubleshoot using a modification to the following: http://kb.vmware.com/kb/1002511

All the step in this section are important !!!

a. Identify and record the exact size of the -flat file using a command similar to:

# ls -l esxconsole-flat.vmdk

-rw------- 1 root root 4294967296 Oct 11 12:30 esxconsole-flat.vmdk

Write down this number (4294967296) it could be different in your case, it is usually 8GB !

b. Rename the file, as all the valuable data is in this file !

# mv esxconsole-flat.vmdk esxconsole-flat_ORIG.vmdk

c. Use the vmkfstools command to create a new virtual disk:

# vmkfstools -c 4294967296 -a buslogic esxconsole.vmdk

Remember to use buslogic as the bus type.

d. Rename the new blank created disk file esxconsole-flat.vmdk

# mv esxconsole-flat.vmdk esxconsole-flat_BLANK.vmdk

e. Rename the old console disk to the new file

# mv esxconsole-flat_ORIG.vmdk esxconsole-flat.vmdk

Type exit, or reboot the ESX server.

You will be able to boot the server normally.

Later, you can delete the file esxconsole-flat_BLANK.vmdk

Problem solved !

Note:

If the esxconsole-flat file does not exist in step 5, you must re-install the ESX host to recreate the service console.

Original VMware KBs:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1012874

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1002511

/*.vmdk
values in the output.
/esxconsole.vmdk"

Vsphere ESX NIC numbering

2011-05-06T07:03:00.001-07:00

VMware had an issue with the nics port numbering. If you have on board nics, and some PCIe nics, the numbering is not correct. With HP server and Broadband and Intel adapter it happens.

It pretty much assigns them in whatever order it finds them - you can see this article (http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1002315) for a rundown on the process. Now if you are really dead set on changing them it can be done. You would have to:

You can change the numbering by changing the esx.conf

1. go into the console (tech support mode on ESXi)

2. cd /etc/vmware

3. backup your esx.conf

eg. cp esx.conf esx.conf.bak

4. edit esx.conf and look for your vmnic entries.. will look something like

/device/000:001:00.0/vmkname = "vmnic0"

/device/000:001:00.1/vmkname = "vmnic1"

/device/000:002:00.0/vmkname = "vmnic2"

/device/000:002:00.1/vmkname = "vmnic3"

5. Order as desired by editing the string vmnicX

6. Look for mac address assignment to vmnicX and change them accordingly, change the lines for the mac "xx:xx:xx:xx:xx:xx" and virtualmac "yy:yy:yy:yy:yy:yy" to be consistent. Don't change just the "vmnicX", leave everything in the same place.

/net/pnic/child[000X]/mac/ = "xx:xx:xx:xx:xx:xx"

/net/pnic/child[000X]/name/ = "vmnicX"

/net/pnic/child[000X]/virtualmac/ = "yy:yy:yy:yy:yy:yy"

7. Save the edited file and reboot

You may have to readjust your nic bindings in networking in the Virtual Center when done.

For many implementations, the numbering is not an issue, but for a correct design (using nic port to a specific Switch port) and validate the cabling the right numbering is important. The use of host profiles is standardized, including the nic names, which makes things easier to maintain with less efforts.

Example: We use vmnic0 and vmnic5 for service console and vmkernel for iscsi, and vmnic1 and vmnic4 for Virtual Machines Data, if the numbering is not correct, you can use the same nic/port for High Availability, if you have a nic problem, both nics/ports can be the some physical port, and you have no vmkernel, or Service Console

This is just an example what can happen if you have your infrastructure very well documented, and the correct design for High Availability on all connections.

I hope It is useful for you as it was for me !

VMware vcenter server migration from 4.0 to 4.1

2011-01-20T13:04:00.001-08:00

VMwAre Vcenter server is used for maintaining the esx servers from a centralized place with user permission and cluster creation and the licensing issues.

New version 4.1 MUST be installed on a Windows 64 bit OS computer.

I migrated it from an old server to a new one, so I had to proceed with a migration.

While migrating from 4.0 to 4.1, we need to follow these steps for getting old database converted to new format, as it is different from 4.0 to 4.1.

Before migration, the following services of vcenter should be stopped

VMware VirtualCenter Server

VMware VirtualCenter Management Webservices

VMware vCenter Update Manager Service

Mount the vcenter ISO image or load the bunt DVD in the old vcenter server machine. Open the cd and copy the Datamigration folder to C:\Datamigration

Extract all the file in the same folder.

IMPORTANT: Verify that you have at least 8 GB of available space, as many configuration files will be copied to C: drive.

Navigate to C:\Datamigration\ and run backup.bat , the script will backup all configuration settings from your recent vCenter installation and database. (Software builds, used ports, database information, server names and VUM Settings/Patches etc.).. once finished all the important data is stored in C:\Datamigration\Data\
If there are any errors while making the backup… check this and fix before you go further!
Now you need to copy the C:\Databasemigration\ folder to your new planned vCenter 4.1 server. You can do this by share, copy this on USB stick or whatever.

Migrate the database and install vCenter 4.1:
- Login to the new vCenter server;
- Mount the new VMware vCenter Server 4.1 and modules
Open CMD:

- Navigate to C:\Data migration\ and run install.bat. The script will check if the correct data is present..

If you used a different name for your new vCenter server press Yes.. to continue

Then you must select the vCenter 4.1 and VUM installation source. In my case the mounted ISO has drive letter F:\

The configuration will be validated, correct ports numbers, vCenter serial number etc.. all good..

.. The vCenter Installation is started

I already installed a Microsoft SQL 2005 Enterprise server (local) and created a 32 bit ODBC connection, THEN select "vCenter41" DSN

If needed, give the correct credentials

You can modify this later, please check: http://kb.vmware.com/kb/1001046 for more information

- I changed the installation path to D:\Program Files\VMware\Infrastructure\ .. default location is C:\..\.

Oke, the installation was not so difficult. After clicking finish the install.bat will continue with the VMware Update Manager database migration and installation.

VMware Update Manager – Database migration and installation software:

As you can see "vCenter Server migration installed completed successfully" great

The install.bat script will continue and check again if the selected VUM ports are available and if the copied data migratable is for the new VUM database location

For VMware Update Manager you need to create a 64-Bit DSN. You can create this here: C:\WINDOWS\SysWOW64\odbcad32.exe .. oke, thats done.. select the VUM (already created before installation) database.

The installation and patch download location is by default C:\.. I prefer to install this data on a separate disk.. so I changed the installation path to D:\…\..

Now you can connect your vCenter server and manage your hosts and VM's.. sometimes you can't!

Tip before connect the vCenter:

- Reboot your new vCenter 4.1 server;

- On the ESX host: Restart your management services: service mgmt-vmware restart

- On the ESX host: Use a text editor to view/change the IP address inside the xxx.xxx.xxx.xxx tags the following file:/etc/opt/vmware/vpxa/vpxa.cfg

Finally result:

Successful migration process of vCenter 4.0 to new 4.1 server.

How to fix VMware error fsck.ext3 Unable to resolve UUID with no data loss

2010-12-02T13:19:00.001-08:00

It happened to me after a power failure, that damaged a server of our vmware farm. The resolution is presented below:

ESX 4.0 host fails to boot after power operation with the error: fsck.ext3: Unable to resolve UUID

Symptoms

After power-cycling or rebooting an ESX 4.x server, the following error message is produced during boot:
fsck.ext3: Unable to resolve 'UUID=34d192db-17eb-442e-9613-c5c24c6fa9fa'

And
*** An error occurred during the file system check.
*** Dropping you to a shell; the system will reboot
*** when you leave the shell.
After encountering this error, you are unable to boot into ESX or Troubleshooting mode.
The unresolvable EXT file systems or partitions most commonly later appear to have mount points such as /var, /opt and /tmp.

Resolution

This issue occurs when the boot-time file system check utility (FSCK) for EXT-3 file systems cannot resolve a file system (by UUID) defined in /etc/fstab.

Issues that can result in this may include:

The default roll-back option is left enabled when a subsequent upgrade is being performed.
The device not present during system boot.
The unresolvable EXT file systems appear to reside on disks/devices that are initialized later during system boot (e.g. the last LUN).

Note: If you are experiencing an outage with virtual machines down, consider resolving the situation in a timely manner through the reinstallation of VMware ESX. Troubleshooting may take more time than a reinstallation, which is in the order of approximately 20 minutes.

Otherwise refer to instructions below for submission of information to VMware Technical Support for technical analysis.

Further troubleshooting is available in the shell:

Confirm the UUIDs which were not resolvable, and remain so, by running fsck again without additional arguments. Information similar to the following is displayed:

# fsck

fsck 1.39 (29-May-2006)
e2fsck 1.39 (29-May-2006)
esx-root: clean, 32953/641280 files, 414801/1281175 blocks
e2fsck 1.39 (29-May-2006)
/dev/sdt1: clean, 35/140832 files, 25323/281596 blocks
fsck.ext3: Unable to resolve 'UUID=34d192db-17eb-442e-9613-c5c24c6fa9fa'
e2fsck 1.39 (29-May-2006)
/dev/sdt6: clean, 31/250368 files, 27851/500220 blocks
e2fsck 1.39 (29-May-2006)
/dev/sdt7: clean, 22/250368 files, 16815/500220 blocks
Record the UUID or UUIDs which failed to resolve. You may take a screen shot of your System Management Interface, take a picture, or write the values down.
Confirm these same values in the /etc/fstab file.
# cat /etc/fstab

UUID=79815890-f11c-4907-80fe-d1cd6bf061f8 /        ext3    defaults                  1 1
UUID=45460133-027b-40b6-8b4d-e52aaf4c417f /boot    ext3    defaults                  1 2
None                    /dev/pts                   devpts defaults                  0 0
/dev/cdrom              /mnt/cdrom                 udf,iso9660 noauto,owner,kudzu,ro 0 0
/dev/fd0                /mnt/floppy                auto    noauto,owner,kudzu    0 0
None                    /proc                      proc    defaults                  0 0
None                    /sys                       sysfs   defaults                  0 0
UUID=34d192db-17eb-442e-9613-c5c24c6fa9fa
/var/log ext3 defaults,errors=panic     1 2
UUID=e32ec5f4-d795-414a-8d73-a2bb3ea86342 swap     swap    defaults         0 0

Note: Highlighted in blue is the mount point for the respective unresolvable UUID, in red.
Verify what UUIDs the system is currently aware of by running the following command:
# ls -l /dev/disk/by-uuid

total 0
lrwxrwxrwx 1 root root 10 Nov 9 14:36 45460133-027b-40b6-8b4d-e52aaf4c417f -> ../../sdm1
lrwxrwxrwx 1 root root 10 Nov 9 14:36 e32ec5f4-d795-414a-8d73-a2bb3ea86342 -> ../../sdr1
lrwxrwxrwx 1 root root 10 Nov 9 14:36 34d192db-17eb-442e-9613-c5c24c6fa9fa -> ../../sdr2
lrwxrwxrwx 1 root root 10 Nov 9 14:36 79815890-f11c-4907-80fe-d1cd6bf061f8 -> ../../sdr5

Notes:
- This output reveals the UUID-to-partition relationship for all discovered EXT partitions in the system. Affected mount points or content can be associated using the previous step.
- It is possible in some environments that none of the known partitions reported by listing /dev/disk/by-uuid match the unresolved UUID. This is correctable; for additional instructions, proceed to the following sections and correct the content of the /etc/fstab file.

Solution

VMware is currently investigating further for a full root-cause and solution. Workarounds are available below.

If you are able to reproduce this issue while maintaining production via alternate servers, contact VMware Technical Support after completing the following:

Log into the terminal of the affected ESX server.
Remount the root partition in read-write mode:
# mount / -o remount,rw
Configure Serial Line Logging per the section Configuring the Service Console for VMware ESX 3.x and 4.x in KB article: Enabling serial-line logging for an ESX and ESXi host (1003900).
Reboot the ESX server and log the results via your listening serial terminal.
Contact VMware Technical Support and file a Support Request. For additional information, see Filing a Support Request (1021619).

Workarounds

Both recommended workarounds involve the modification of the /etc/fstab file. You may either:

Generate a new UUID for the affected file system(s) and update /etc/fstab to match the new value(s).
Update /etc/fstab to incorporate the correct UUID from the file system.

Applying a new UUID

Apply a new UUID to the EXT-3 file systems which fail to resolve and update the /etc/fstab file.

Run tune2fs against each Linux partition on the suspected disk device. For example:
# tune2fs -l /dev/sdr2 | grep UUID
Filesystem UUID: 34d192db-17eb-442e-9613-c5c24c6fa9fa

# tune2fs -U random /dev/sdr2
tune2fs 1.39 (29-May-2006)

# tune2fs -l /dev/sdr2 | grep UUID
Filesystem UUID: 25a18c70-ffcb-4b15-9d2d-1cfab1754d86
Update /etc/fstab with the updated UUID. From earlier steps, /dev/sdr2 partition was determined to be the /var/log mount point:
1. Remount the root partition in read-write mode:
  # mount / -o remount,rw
2. Open the /etc/fstab file for re-writing. For more information, see Editing configuration files in VMware ESX (1017022).
3. Search for, and change, the original UUID to the newly-generated UUID from earlier steps, above.
4. Save the file and remount the root partition in read-only mode:
  # mount / -o remount,ro
5. Reboot the server using shutdown -r now.

You can read the full document at (check the "mount" syntax):

http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1017162&sliceId=1&docTypeID=DT_KB_1_1&dialogID=127160699&stateId=0%200%20138435051

How to setup a NFS server to archive Cisco Mars logs

2010-11-24T12:43:00.001-08:00

For the purpose of archive Cisco Mars logs using a NFS Server.

Now NFS is supported natively in Linux, and is what Cisco would recommend for your NFS storage, which is quite simple to set up....
NFS Setup for Linux

1) As root, create a directory for the archive data eg,..

mkdir -p /archive/MARSBox
chown -R nobody.nobody /archive
chmod -R 777 /archive

2) In the /etc/exports file, add the following...

/archive/MARSBox MARS_IP_Address (rw)

3) Restart the NFS Service...

/etc/init.d/nfs restart

But what if we want to do this with Windows? Well we can use Windows Services for UNIX (WSU). This allows an NFS mount to be created on a Windows file server.

Windows Services for UNIX Setup

This can be downloaded from HERE current version is 3.5, filename SFU35SEL_EN.exe

1) Extract this to a folder on your windows box, and run SfuSetup.msi

2) Click NEXT to Continue

3) Enter values for the Username and Organization fields, and click NEXT

4) ACCEPT the agreement option, and Click NEXT

5) Select the CUSTOM Installation option, and NEXT
6) As a minimum, and for this example, you must select Entire Feature (including any subfeatures if any) will be installed on local hard drive, for the following components..

NFS (see note below)
Authentication tools for NFS

But, make sure you deselect Gateway for NFS, or else you will get this error below...

7) Verify that Change the default behaviour to case sensitive check box is NOT TICKED, then click NEXT.
8) The Username Mapping Panel appears. Verify that...

Local User Name Mapping Server
Network Information Service (NIS)

are selected, then click NEXT.

9) Enter the Windows Domain name, the NIS Domain and Server are optional, click NEXT.

10) Enter the desired location for the Windows Service for UNIX install, (Not MARS Archive Share), and click NEXT.

11) Click FINISH, and REBOOT.
Now you have successfully install the NFS Windows Component, we are now ready to define a share to used by the MARS appliance.
Define a NFS Share on Windows

1) In Windows Explorer, create a folder for MARS to Archive to.

2) Right-Click the folder, and select the NFS Sharing Tab.

3) Select Share this folder, and enter a share name. Encoding ANSI.

4) Select Allow Anonymous Access

5) Click on Permissions, and select ALL Machines, and No Access

6) Now click ADD, and type the IP Address of your MARS Box, with Read-Write, and ANSI Encoding.

7) Click OK, and Apply.

8) From a DOS Window, type the following, to modify the shared folder permissions so that Everyone has local filesystem access to the folder.

cd share
cacls share /E /G everyone:F

8) Under Administration Tools/Local Security Policy / Security Options

Double click.. Network Access: Let Everyone permissions apply to anonymous users, and select Enabled. Then click OK.

You have now completed the NFS configuration for the Windows Server.

Check your share issuing the command "showmount –e"

Before we configure MARS to Archive to the NFS share, there is one last thing that is recommended. This is to add the NFS Client, which is the MARS Box, to the hosts file

/etc/hosts on Linux
Windows\system32\drivers\etc on Windows

And also Add the MARS Appliance to your internal DNS.

CS-MARS Archive Configuration

1) Select Admin / System Maintenance / Data Archiving

2) In the Remote Host IP Field, enter the IP Address of your NFS Server

3) In the Remote Path Field, enter the export path on the NFS Server

(In Windows a forward slash is required to resolve the UNC Share name)

4) Archiving Protocol, NFS is the only option at the moment!

5) Remote Storage Capacity in Days - enter one of the following...

The maximum number of days for which you want the NFS server to retain data. The NFS Server keeps your data for the number of days previous to the current date.
The number of days that the NFS Server can maximally retain, ie the upward capacity of the archive server.

6) Click START, to enable your MARS Archiving

If everything has gone to plan, you should receive a message back of DONE Status OK.

If you see an error message such as "Invalid remote IP or path", your NFS Server may not be correctly configured. I`d check the remote path is correct in the first instance.

In a Windows environment, we can also enable logging of NFS events...

1) Programs/ Windows Services for UNIX/ Services for UNIX Administration

2) Select Server for NFS

3) Under Logging, tick all the boxes, and specify a folder where you want to place the log file.

4) Click Apply to save changes.

Thats the Archiving all set up.

How to Backup the DHCP Database (on Win2K3) and Restore to another Server (also running Win2K3)

2010-10-27T08:46:00.001-07:00

To move a DHCP database and configuration from a server that is running Windows Server 2003 to another server that is running Windows Server 2003:

Log on to the source DHCP server by using an account that is a member of the local Administrators group.
Click Start, click Run, type cmd in the Open box, and then click OK.
Type netsh dhcp server export C:\dhcp.txt all, and then press ENTER.

Install the DHCP server service on the server that is running Windows Server 2003

To install the DHCP Server service on an existing Windows Server 2003-based computer:

Click Start, click Control Panel, and then double-click Add or Remove Programs.
Click Add/Remove Windows Components.
In the Windows Component Wizard, click Networking Services in the Components box, and then click Details.
Click to select the Dynamic Host Configuration Protocol (DHCP) check box if it is not already selected, and then click OK.
In the Windows Components Wizard, click Next to install the selected components. Insert the Windows Server 2003 CD into your computer CD drive or DVD drive if you are prompted to do this. Setup copies the DHCP server and tool files to your computer.
When Setup is complete, click Finish.

Import the DHCP database

Log on as a user who is an explicit member of the local Administrators group. A user account in a group that is a member of the local Administrators group will not work. If a local Administrators account does not exist for the domain controller, restart the computer in Directory Services Restore Mode, and use the administrator account to import the database as described later in this section.
Copy the exported DHCP database file to the local hard disk of the Windows Server 2003-based computer.

Verify that the DHCP service is started on the Windows Server 2003-based computer.

Click Start, click Run, type cmd in the Open box, and then click OK.
At the command prompt, type netsh dhcp server import c:\dhcp.txt all, and then press ENTER, where c:\dhcp.txt is the full path and file name of the database file that you copied to the server.

Authorize the new DHCP server

Click Start, point to All Programs, point to Administrative Tools, and then click DHCP.
In the console tree of the DHCP snap-in, expand the new DHCP server. If there is a red arrow in the lower-right corner of the server object, the server has not yet been authorized.
Right-click the server objects, and then click Authorize.
After several moments, right-click the server again, and then click Refresh. A green arrow indicates that the DHCP server is authorized.

sendmail and sm-client very slow to start

2010-09-24T07:39:00.001-07:00

After changing the IP address of a server, at the time of booting up sendmail and sm-client took a very long time (about 5 minutes each) to start.

Usually when sendmail is sluggish starting - it's because it can't figure out hostname details.

# cat /etc/hosts

127.0.0.1 localhost.localdomain localhost

above needs to be the very first line of /etc/hosts

if you are accepting email for a domain then it would help if you have

the fully qualified domain name set in /etc/sysconfig/network and that

name resolves via dns or at least is listed with an ip address

in /etc/hosts...

i.e.

# hostname

linuxserver.mydomain.com

# cat /etc/sysconfig/network

NETWORKING=yes

HOSTNAME=linuxserver.mydomain.com

# cat /etc/hosts

# Do not remove the following line, or various programs

# that require network functionality will fail.

127.0.0.1 localhost.localdomain localhost

192.168.0.1 linuxserver.mydomain.com linuxserver

# host linuxserver.mydomain.com

linuxserver.mydomain.com has address 192.168.0.1

# cat /etc/mail/local-host-names

mydomain.com

linuxserver.mydomain.com

www.mydomain.com

localhost

localhost.localdomain

That's it !

Linux LVM tips

2010-09-21T10:19:00.001-07:00

LVM Tools

LVM Tool	Description
pvcreate	Create physical volume from a hard drive
vgcreate	Create logical volume group from one or more physical volumes
vgextend	Add a physical volume to an existing volume group
vgreduce	Remove a physical volume from a volume group
lvcreate	Create a logical volume from available space in the volume group
lvextend	Extend the size of a logical volume from free physical extents in the logical volume group
lvremove	Remove a logical volume from a logical volume group, after unmounting it
vgdisplay	Show properties of existing volume group
lvdisplay	Show properties of existing logical volumes
pvscan	Show properties of existing physical volumes

Operations on Logical Volumes

Among typical operations:

A Walkthrough of the LVM for Linux

Adding a disk to the Volume Group

Next, we'll add /dev/hda6 to the Volume Group. Just type vgextend vg01 /dev/hda6 and you're done! You can check this out by using vgdisplay -v vg01. Note that there are now a lot more PEs available!

Moving Creating a striped Logical Volume

Note that LVM created your whole Logical Volume on one Physical Volume within the Volume Group. You can also stripe an LV across two Physical Volumes with the -i flag in lvcreate. We'll create a new LV, lv02, striped across hda5 and hda6. Type lvcreate -l4 -nlv02 -i2 vg01 /dev/hda5 /dev/hda6. Specifying the PV on the command line tells LVM which PEs to use, while the -i2 command tells it to stripe it across the two.

You now have an LV striped across two PVs!

Moving data within a Volume Group

Up to now, PEs and LEs were pretty much interchangable. They are the same size and are mapped automatically by LVM. This does not have to be the case, though. In fact, you can move an entire LV from one PV to another, even while the disk is mounted and in use! This will impact your performance, but it can prove useful.

Let's move lv01 to hda6 from hda5. Type pvmove -n/dev/vg01/lv01 /dev/hda5 /dev/hda6. This will move all LEs used by lv01 mapped to PEs on /dev/hda5 to new PEs on /dev/hda6. Effectively, this migrates data from hda5 to hda6. It takes a while, but when it's done, take a look with lvdisplay -v /dev/vg01/lv01 and notice that it now resides entirely on /dev/hda6!

Removing a Logical Volume from a Volume Group

Let's say we no longer need lv02. We can remove it and place its PEs back in the empty pool for the Volume Group. First, unmounting its filesystem. Next, deactivate it with lvchange -a n /dev/vg01/lv02. Finally, delete it by typing lvremove /dev/vg01/lv02. Look at the Volume Group and notice that the PEs are now unused.

Removing a disk from the Volume Group

You can also remove a disk from a volume group. We aren't using hda5 anymore, so we can remove it from the Volume Group. Just type vgreduce vg01 /dev/hda5 and it's gone!

A file system on logical volume may be extended. Also more space may be added to a VG by adding new partitions or devices with the command: vgextend. For example:

lvextend -L +4G /dev/VolGroup00/LogVol04

The command pvmove can be used in several ways to move any LV elsewhere. There are also many more commands to rename, remove, split, merge, activate, deactivate and get extended information about current PV's, VG's and LV's.

Here is a typical du map of a server with volume manager installed. As you can see all partitions except /boot partition are referred vi path /dev/mapper/VolGroup00-LogVolxx where xx is two digit number:

Filesystem 1K-blocks Used Available Use% Mounted on

/dev/mapper/VolGroup00-LogVol00

4128448 316304 3602432 9% /

/dev/sda3 194449 22382 162027 13% /boot

none 2020484 0 2020484 0% /dev/shm

/dev/mapper/VolGroup00-LogVol05

4128448 42012 3876724 2% /home

/dev/mapper/VolGroup00-LogVol03

4128448 41640 3877096 2% /tmp

/dev/mapper/VolGroup00-LogVol02

8256952 3189944 4647580 41% /usr

/dev/mapper/VolGroup00-LogVol04

8256952 174232 7663344 3% /var

/dev/hde 594366 594366 0 100% /media/cdrecorder

Resiliency to renumbering of physical hard disks

LVM identifies PVs by UUID, not by device name.

Each disk (PV) is labeled with a UUID, which uniquely identifies it to the system. 'vgscan' identifies this after a new disk is added that changes your drive numbering. Most distros run vgscan in the lvm startup scripts to cope with this on reboot after a hardware addition. If you're doing a hot-add, you'll have to run this by hand I think. On the other hand, if your vg is activated and being used, the renumbering should not affect it at all. It's only the activation that needs the identifier, and the worst case scenario is that the activation will fail without a vgscan with a complaint about a missing PV.

The failure or removal of a drive that LVM is currently using will cause problems with current use and future activations of the VG that was using it.

How to get information about free space

vgdisplay shows logical volumes one by one and provides the information about free disk space on each:

vgdisplay volume_group_one | grep "Total PE"

How to create a new volume

# vgcreate vg01 /dev/hda2 /dev/hda10
Volume group "vg01" successfully created

How to create and mount a partition

Create the partition with lvcreate

# lvcreate -L 5G -n data vg02
Logical volume "data" created
Format partition

# mkfs -t ext3 /dev/vg02/data
Make mount point and mount it

# mkdir /data
# mount /dev/vg02/data /data/
Check results

# df -h /data
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/test--volume-data
50.0G 33M 5.0G 1% /data
Add it to /etc/fstab

How to extend the partition

If one wishes to use all the free physical extents on the volume group one can achieve this using the lvm
lvextend command :

lvm lvextend -L +4G /dev/VolGroup00/LogVol04 # extend /var

ext2online /dev/VolGroup00/LogVol04

Option -l operates with free extents . This adds the 7153 free extents to the logical volume:

# lvm lvextend -l+7153 /dev/TestVG/TestLV

Extending logical volume TestLV to 30.28 GB

Logical volume TestLV successfully resized

"lvextend -L +54 /dev/vg01/lvol10 /dev/sdk3" tries to extend the size of that logical volume by 54MB on physical volume /dev/sdk3. This is only possible if /dev/sdk3 is a member of volume group vg01.

Then the pvcreate command is used to create the new physical volume using the new partition, and the pvs again to verify the new physical volume. See redhat.com Knowledgebase

How to remove LVM partionon

Use lvremove to Remove a logical volume from a logical volume group, after unmounting it

syntax:

lvremove [-A/--autobackup y/n] [-d/--debug] [-f/--force] [-h/-?/--help] [-t/--test] [-v/--verbose] LogicalVolumePath [LogicalVolumePath...]

lvremove removes one or more logical volumes. Confirmation will be requested before deactivating any active logical volume prior to removal. Logical volumes cannot be deactivated or removed while they are open (e.g. if they contain a mounted filesystem).

Options.

-f, --force
Remove active logical volumes without confirmation.

EXAMPLES
Remove the active logical volume lvol1 in volume group vg00 without
asking for confirmation:

lvremove -f vg00/lvol1

Remove all logical volumes in volume group vg00:

lvremove vg00

TIPS:

Missing drives in a volume group have caused me a lot of problems. If you just want to excommunicate the drive from your vg, the following works:

vgreduce --removemissing vg00

# pvscan