ESXi – Automatic Backups


Did you know that ESXi does an hourly backup of its configuration files? Have a look at the crontabs for root account: cat /var/spool/cron/crontabs/root

#syntax : minute hour day month dayofweek command
01 01 * * * /sbin/tmpwatch.sh
01 * * * * /sbin/auto-backup.sh #first minute of every hour (run every hour)

So auto-backup.sh is the script that is triggered hourly to backup ESXi. Let’s see what’s in there: cat /sbin/auto-backup.sh

#!/bin/ash
export PATH=/sbin:/bin
#PXE boot?
if [ ! -d /bootbank ]; then
exit 1
fi
first=0
if esxcfg-info -e; then
if [ ! -f /bootbank/local.tgz ]; then
first=1
else
mkdir -p /tmp/auto-backup.$$.dir
cp /bootbank/local.tgz /tmp/auto-backup.$$.dir
fi
else
if [ ! -f /bootbank/state.tgz ]; then
first=1
else
mkdir -p /tmp/auto-backup.$$.dir
tar zxvf /bootbank/state.tgz -C /tmp/auto-backup.$$.dir
fi
fi
if [ “$first” = “1” ]; then
#always do the first one
backup.sh 0
if [ $? -ne 0 ]; then
logger “Auto-Backup failed”
fi
exit 0
fi
tar zxvf /tmp/auto-backup.$$.dir/local.tgz -C /tmp/auto-backup.$$.dir
filestosave=`find /etc -follow -type f -name “.#*” | sed ‘s/\.#\(.*\)/\1/g’`
for filename in $filestosave
do
diff -N $filename /tmp/auto-backup.$$.dir$filename
if [ $? -ne 0 ]; then
backup.sh 0
if [ $? -ne 0 ]; then
logger “Auto-Backup failed”
fi
break
fi
done
#clean up
rm -rf /tmp/auto-backup.$$.dir

What is the /bootbank mentioned in the script? The /bootbank is a 48MB partition which contains the 32MB core hypervisor code. It contains the following files:

~ # ls -1 /bootbank/
aam.vgz
boot.cfg
cim.vgz
cimstg.tgz
license.tgz
mod.tgz
oem.tgz
pkgdb.tgz
state.tgz <- that’s our backup, less than 10KB in standalone or less than 100KB when part of a HA cluster (aam)
sys.vgz
vmk.gz
vmkboot.gz
vpxa.vgz
Charu Chaubal, Technical Marketing Manager at VMware has written an excellent document about The Architecture of VMware ESXi. It’s a 10 pages white paper that worth a read!
Now for the fun let’s run the script: /sbin/auto-backup.sh

~ # /sbin/auto-backup.sh
config implicitly loaded
local.tgz
etc/vmware/vmkiscsid/vmkiscsid.db
etc/dropbear/dropbear_dss_host_key
etc/dropbear/dropbear_rsa_host_key
etc/opt/vmware/aam/configBackup.tar.gz
etc/opt/vmware/vpxa/vpxa.cfg
etc/opt/vmware/vpxa/dasConfig.xml
etc/opt/init.d/vmware-aam
etc/sysconfig/network
etc/vmware/hostd/authorization.xml
etc/vmware/hostd/hostsvc.xml
etc/vmware/hostd/pools.xml
etc/vmware/hostd/vmAutoStart.xml
etc/vmware/hostd/vmInventory.xml
etc/vmware/hostd/proxy.xml
etc/vmware/ssl/rui.crt
etc/vmware/ssl/rui.key
etc/vmware/vmkiscsid/initiatorname.iscsi
etc/vmware/vmkiscsid/iscsid.conf
etc/vmware/vmware.lic
etc/vmware/config
etc/vmware/dvsdata.db
etc/vmware/esx.conf
etc/vmware/license.cfg
etc/vmware/locker.conf
etc/vmware/snmp.xml
etc/group
etc/host.conf
etc/hosts
etc/inetd.conf
etc/chkconfig.db
etc/nsswitch.conf
etc/passwd
etc/random-seed
etc/resolv.conf
etc/shadow
etc/sfcb/repository/root/interop/cim_indicationfilter.idx
etc/sfcb/repository/root/interop/cim_indicationhandlercimxml.idx
etc/sfcb/repository/root/interop/cim_listenerdestinationcimxml.idx
etc/sfcb/repository/root/interop/cim_indicationsubscription.idx
— /etc/vmware/license.cfg Fri Feb 12 17:07:04 2010
+++ /tmp/auto-backup.220438.dir/etc/vmware/license.cfg Fri Fe
b 12 17:06:04 2010
@@ -1,5 +1,5 @@

– AQD+yggAAABQn0ksiuhfjI8tx1W6jQAAADRvNHwiujst6g6cz1zqj
PU0X5EWq2+BI2Eos/M1L97wCcL0idjmsnu2UEsC+HdKOhL99
+ AQD+ygksj83gAAAC7A3ExRK/5GDQAAAA/sfbAUxyd,mfvimjsbd
V1dUYVMJHzJXwHQSGvy9wQ1GsdfsKIZLyf6diroKZk8EVlDzSeval

\ No newline at end of file
config implicitly loaded
Saving current state in /bootbank
Clock updated.
Time: 17:07:17 Date: 02/12/2010 UTC

You could also invoke the backup manually with the vSphere PowerCLI: Get-VMHost MyESXiHost | Set-VMHostFirmware -BackupConfiguration -DestinationPath C:\Temp
Knowing that we have an hourly backup of of ESXi host, you could also do a daily backup to a backup storage and do it for all your ESXi hosts at once. NiTRo from Hypervisor.fr came up with the following nice script to achieve that:

$backpath = “x:\<your backup storage path>\”
$eVMHs = Get-View -ViewType HostSystem |?{$_.config.product.ProductLineId -eq “embeddedEsx”} |?{$_.Runtime.ConnectionState -eq “connected”}
Foreach ($eVMH in $eVMHs)
{Set-VMHostFirmware -VMHost $eVMH.name -BackupConfiguration -DestinationPath $backpath}

Now that we saw how to backup, let’s try a restore from vSphere PowerCLI.
Step#1, put the ESXi host is maintenance mode, this is a requirement:
set-VMHost -vmhost MyESXiHost -state Maintenance
Step#2, restore the config bundle:
Get-VMHost MyESXiHost | Set-VMHostFirmware -Restore -SourcePath C:\Temp\configBundle-MyESXiHost.tgz
You can eventually add the -Force if the bundle is mismatched, that is when you restore to a different ESXi build.

Sources: VMware.com, Virtu-al.net

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About PiroNet

Didier Pironet is an independent blogger and freelancer with +15 years of IT industry experience. Didier is also a former VMware inc. employee where he specialised in Datacenter and Cloud Infrastructure products as well as Infrastructure, Operations and IT Business Management products. Didier is passionate about technologies and he is found to be a creative and a visionary thinker, expressing with passion and excitement, hopefully inspiring and enrolling people to innovation and change.
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5 Responses to ESXi – Automatic Backups

  1. deinoscloud says:

    William Lam posted today a very good script that allows a user to capture and store some basic configurations from an ESXi host and provides a way to import and apply these configurations to a newly fresh built ESXi host.

    More at http://communities.vmware.com/docs/DOC-11969

  2. William Lam says:

    I also wrote a script in which you can schedule automatic backups of your ESX(i) host(s) – http://communities.vmware.com/docs/DOC-11767

    –William

  3. deinoscloud says:

    William many thanks for the info ;)

  4. Pingback: How to backup esxi using powercli? « Designing vSphere

  5. Pingback: VMware vSphere Fast Track Day#5 – Lessons Learned « DeinosCloud

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