Archive for the ‘Scripting/Programming’ Category

BackupExec 2012 (14) on newer Linux

Tuesday, August 6th, 2013

In particular – Oracle UEK, which “claims” to be 2.6.39-xxx, but is actually 3.0.x with a lower version number. Several misbehaviors (or differences) of version 3 can be found. One of them is related to BackupExec. The service would not start on OEL6 with UEK kernels. The cause of it is an incorrect use of a function – getIfAddrs. Everything can be seen in this amazing post. The described patch works, at least to allow the service to start. Check out the comments for some insights about how to identify the correct call.

I am re-posting it here, so it can be found for Oracle Universal Enterprise Kernel (UEK) as well.

Cacti NetApp Ontap API data query

Sunday, June 23rd, 2013

I have been using the excellent template and scripts from this forum post, however, when the NetApp device is loaded with LUNs and volumes, the script will cause the Cacti to timeout, and during that time, consume CPU. The original cause of this problem was a workaround to some NetApp Perl API bug the original author found, which forced him to query the entire data set for each sub-query. This is nice for five, or even ten volumes, but when you’re around 400 volumes, things just look bad.

Due to that, I have taken upon myself to make this script more scalable, but forcing a single data query from the NetApp for each data type (volume, LUN, system, etc) and data query type (get, index, etc). A unique file was created with its name being the storage_device_name.data_type.query_type. Following queries to any subset of this data were just accessing this file, and not the remote NetApp device, killing network, CPU, and tending to time out on operation and leave huge blank parts in the graphs.

I will post my modified template in the forum as well, but I place it here, just so that it will be both available for me, and for any interested reader.

Get it here:NetApp_OnTap-SDK_cacti-20130623.tar.gz


XenServer – Setting virtual disks names based on the VM names

Wednesday, January 2nd, 2013

One of the worst things you can have in XenServer, is some wize-guy performing a ‘forget storage’ on a storage device still holding virtual disks related to VMs. As XenServer database is internal (for the whole pool) and not per-VM, all references to this virtual disks disappear, and you remain with bunch of VMs without disks, and later on, when the recovered from the shock and restored the SR, with a bunch of virtual disks you have no clue as to where they belong. Why? Because we are lazy, and we tend to skip the part where you can (or is it – should?) define a custom name for your virtual disks so you would know later on (for example – in the case specified above) where they belong(ed).

To solve this annoying issue, and to save time for Citrix XenServer admins, I have created a script which resets the VDI (virtual disk object) names to the name of the VM+ the logical position of the virtual disk (example: xvda, hdb, etc), related to the VM. That way, it will become very easy to identify the disks in case of such annoying micro-catastrophy (micro because no data is lost, just where it belongs…).

The script can be called manually, and since we’re lazy people, and we will forget to handle it manually every said interval, and will accumulate virtual machines with “Template of XYZ” virtual disks, it can be called from cron. When called manually, it asks the user to proceed by pressing ‘Enter’. If called from cron, it just runs.



# This script will reset the names of the virtual disks used for each VM to a standard name, based on the VM name
# and the disk position
# It is meant to solve problems where due to 'forget storage' operations or the likes
# virtual disk associations disappear, and you face many disks having the same name
# Written by Ez-Aton:

if [ -t 1 ]
        echo "This script will reset *all* VM disks to a name constructed of the VM and the disk name (xvda, hdb, etc)"
        echo "This operation is not reversible, however, it can be called repeatedly"
        echo "If you want this script to skip a said virtual disk, make sure its name includes the name of the VM"
        echo "For example 'vm1 the real important data disk' for a disk used by vm1."
        echo "Note that the name is case sensitive, and it is very important that to match the name using upper/lower case letters as needed"
        echo "To abort, press Ctrl+C"
        echo "To proceed, press Enter"
        read abc

VM_LIST=`xe vm-list is-control-domain=false --minimal | tr , ' '`

for i in $VM_LIST
        # Resetting several parameters, so we have a clean start
        # We iterate through all existing VMs, to get both their names, and their disks
        VM_NAME="`xe vm-param-get uuid=$i param-name=name-label`"
        if [ -z "$VM_NAME" ]
                # We have a problem with empty VM names, so we will use the VMs uuid
        VBD_LIST=`xe vbd-list vm-uuid=$i --minimal | tr , ' '`
        for j in $VBD_LIST
                # Resetting several parameters, so we have a clean start
                # We iterate through all existing VBDs to reset the VDI nane
                VDI_UUID=`xe vbd-param-get uuid=$j param-name=vdi-uuid`
                if [ "$VDI_UUID" == "" ]
                        # This is a virtual CDROM
                DEV_NAME=`xe vbd-param-get uuid=$j param-name=device`
                VDI_NAME=`xe vbd-param-get uuid=$j param-name=vdi-name-label`

                # Test if the name was reset in the past or manually
                TGT_NAME="$VM_NAME $DEV_NAME"
                if [[ "$TGT_NAME" = "$VDI_NAME" ]]
                        # There is nothing to do
                        echo "Name already includes VM name, so nothing to do"
                        # Here we reset the VDI name
                        echo xe vdi-param-set uuid=$VDI_UUID name-label="$TGT_NAME"
                        xe vdi-param-set uuid=$VDI_UUID name-label="$TGT_NAME"

XenServer get VM by MAC

Wednesday, December 5th, 2012

Using the GUI, it could be somewhat complex identifying a VM based on its MAC address. There are several solutions on the network using PowerShell, but I will demonstrate it using a simple bash script, below. Save, make executable, and run.



if [ -z "$1" ]
	echo "Requires parameter - MAC address"
	exit 1

# You might want to check MAC correctness here. Enjoy doing it. RegExp, man!

# XenServer is agnostic to case for MAC addresses, so we don't care
VIF_UUID=`xe vif-list MAC=$MAC | grep ^uuid | awk '{print $NF}'`

VM=`xe vif-param-list uuid=$VIF_UUID | grep vm-name-label | awk '{print $NF}'`

echo "MAC $MAC has VM $VM"

Attach USB disks to XenServer VM Guest

Saturday, May 5th, 2012

There is a very nice script for Windows dealing with attaching XenServer USB disk to a guest. It can be found here.

This script has several problems, as I see it. The first – this is a Windows batch script, which is a very limited language, and it can handle only a single VDI disk in the SR group called “Removable Storage”.

As I am a *nix guy, and can hardly handle Windows batch scripts, I have rewritten this script to run from Linux CLI (focused on running from the XenServer Domain0), and allowed it to handle multiple USB disks. My assumption is that running this script will map/unmap *all* local USB disks to the VM.

Following downloading this script, you should make sure it is executable, and run it with the arguments “attach” or “detach”, per your needs.

And here it is:

# This script will map USB devices to a specific VM
# Written by Ez-Aton, , with the concepts
# taken from
# and

# Variables
# Need to change them to match your own!
DEVICE_NAMES="hdc hde" # Local disk mapping for the VM

function attach() {
        # Here we attach the disks
        # Check if storage is attached to VBD
        VBDS=`$XE vdi-list sr-uuid=${REMOVABLE_SR_UUID} params=vbd-uuids --minimal | tr , ' '`
        if [ `echo $VBDS | wc -w` -ne 0 ]
                echo "Disks are allready attached. Check VBD $VBDS for details"
                exit 1
        # Get devices!
        VDIS=`$XE vdi-list sr-uuid=${REMOVABLE_SR_UUID} --minimal | tr , ' '`
        for i in $VDIS
                VBD=`$XE vbd-create vm-uuid=${VM_UUID} device=${DEVICE_NAMES[$INDEX]} vdi-uuid=${i}`
                if [ $? -ne 0 ]
                        echo "Failed to connect $i to ${DEVICE_NAMES[$INDEX]}"
                        exit 2
                $XE vbd-plug uuid=$VBD
                if [ $? -ne 0 ]
                        echo "Failed to plug $VBD"
                        exit 3
                let INDEX++

function detach() {
        # Here we detach the disks
        VBDS=`$XE vdi-list sr-uuid=${REMOVABLE_SR_UUID} params=vbd-uuids --minimal | tr , ' '`
        for i in $VBDS
                $XE vbd-unplug uuid=${i}
                $XE vbd-destroy uuid=${i}
        echo "Storage Detached from VM"
case "$1" in
        attach) attach
        detach) detach
        *)      echo "Usage: $0 [attach|detach]"
                exit 1