shared storage within a KVM

[RobFantini]

Hello

I'm looking to set up 2 KVM's to run a high availability dhcp server and later other services like dns for our lan.


Could someone suggest a reliable shared storage system or to to use within 2 or more kvm's? We won't need more the 50MB shared.

We generally use Debian but that is not a requirement.

Or would it be more reliable to just rsync changes as needed?

 

[udo]

Hello

I'm looking to set up 2 KVM's to run a high availability dhcp server and later other services like dns for our lan.


Could someone suggest a reliable shared storage system or to to use within 2 or more kvm's? We won't need more the 50MB shared.

We generally use Debian but that is not a requirement.

Or would it be more reliable to just rsync changes as needed?

Hi,
DRBD is a good choice for that.
Do you serve dhcp-addresse to all clients (synced leases-file), or only from which you know the mac-address?
I don't use free leases and simply use ONA (open network admin) to maintain the hosts and networks and push the dhcp/dns-config to two different systems (in this case one OpenVZ debian and one kvm devil-linux) on different nodes. There must be an big impact to get both servers down...

Udo

 

[RobFantini]

We use isc-dhcp-server which has dhcp failover built in. isc-dhcp failover handles the leased file. Almost all our devices have a fixed lease .

I just read part of https://opennetadmin.com/about and that looks like a much better set up for other admins to use.

What operating system do you use with that?

DRBD in primary/primary mode should work and I'm familiar with it.

I've another question. We'd need to have one main admin address for the 2 KVM's . We've used heartbeat in the past. Can you suggest alternatives to heartbeat?

 

[udo]

We use isc-dhcp-server which has dhcp failover built in. isc-dhcp failover handles the leased file. Almost all our devices have a fixed lease .

Hi Rob,
I also use the isc-dhcp-server but don't care about the lease-file because of allways fixed leases.

I just read part of https://opennetadmin.com/about and that looks like a much better set up for other admins to use.

What operating system do you use with that?

ONA run on the admin-box (also the icinga monitoring) on a debian squeeze (in this case not virtualized). The dns+dhcp-server run also on squeeze (openvz) and devil-linux (kvm). I had to slightly modify the import scripts (build_dhcpd + build_dns).
If you have more than one network for dhcp, it's better to use for dns an seperate server.

DRBD in primary/primary mode should work and I'm familiar with it.

I've another question. We'd need to have one main admin address for the 2 KVM's . We've used heartbeat in the past. Can you suggest alternatives to heartbeat?

Sorry,
don't have experiences with that.

Udo

 

[RobFantini]

Hello Udo

do you use ONA on the squeeze and devil-linux systems? If not what is used to maintain dhcpd.conf ?

 

[udo]

Hello Udo

do you use ONA on the squeeze and devil-linux systems? If not what is used to maintain dhcpd.conf ?

Hi Rob,
yes on both dhcpd and dns-server I use the ona-script build_dhcpd and build_bind to transfer the dhcpd-config and dns-config from the ona-server.

Udo

 

[RobFantini]

yes on both dhcpd and dns-server I use the ona-script build_dhcpd and build_bind to transfer the dhcpd-config and dns-config from the ona-server.

Udo

Hello Udo,
Is there a way to import an existing dhcpd.conf to ona ?

thank you for all the help.

Rob

 

[udo]

Hello Udo,
Is there a way to import an existing dhcpd.conf to ona ?

thank you for all the help.

Rob

Hi Rob,
not directly, but you can easy script the input to feed the ona-database (must define before the network/domain...).

Like

dcm.pl -r host_add host=test.example.com type=2 ip=10.10.6.26 mac=00:03:E6:AC:CC:25

Udo

 

[RobFantini]

In case someone else wants to export dhcpd.conf in to a format to import into ona check this:

https://gist.github.com/4039747

# Author: Matt Pascoe - matt@opennetadmin.com
#
# This awk script is used to extract relavant information from a dhcpd.conf
# config file and build a csv with appropriate fields for passing into
# a dcm.pl module. This can be used to bootstrap a new database from existing
# site data. As usual, inspect the output for accuracy.

to use it

cat dhcpd.conf | ./dhcpparse.awk > fo

and result is:

subnet,10.100.0.0,255.255.0.0,DHCPLOAD-10.100.0.0
pool,10.100.202.100,10.100.202.254,
host,10.100.100.44,00:1F:33:F2:99:BB,dhcpload-10.100.100.44,fbc44
host,10.100.100.45,00:1e:2a:cc:a9:ed,dhcpload-10.100.100.45,fbc45
host,10.100.100.47,00:22:3f:95:25:e7,dhcpload-10.100.100.47,fbc47
host,10.100.100.76,00:1e:2a:cc:a9:e5,dhcpload-10.100.100.76,fbc76
host,10.100.100.57,C4:3D:C7:A2:84:31,dhcpload-10.100.100.57,fbc57
host,10.100.100.77,00:1e:2a:cc:a9:9d,dhcpload-10.100.100.77,fbc77
host,10.100.100.64,00:14:d1:73:7b:19,dhcpload-10.100.100.64,fbc64
host,10.100.100.88,00:C0:B7:70:65:FB,dhcpload-10.100.100.88,fbc88

.....
# we had 200+ more lines

man this is certainly off the subject.

 

[RobFantini]

ONA forum is here: http://opennetadmin.com/newforum.html

 

[RobFantini]

Udo,
thanks for the ona tip. it is 1000 times better then the old way I used, which was directly editing dhcp and dns files and using rsync to put onto many clients.

I put my install notes to : https://github.com/opennetadmin/ona/wiki/Install-on-Debian-notes .

If you get some free time could you check and improve it?

regards
Rob