Personally I'd go with the max memory setup you were talking about but I
wouldn't bother with the NAS.
With only 2 nodes DRBD is fairly easy to setup, it gives you complete
synchronisation of partitions, IE when you write in one place that write
will only come back as ok if it has made it across the network and been
written to disk on the remote machine (depending on settings). If your
ok with a manual change over with a little downtime (in the case of an
intentional transition between servers) I'd put something like ext4 on a
LVM ontop of the DRBD partition mainly to keep things fairly simple. to
migrate machines you shutdown the guests, unmount the file system on
host A, mount it on host B and start the guests there
If you want seemless transitions your going to want something like OCFS
or somesuch for the file system, which gives you the ability to have it
mounted at both locations and hence live migration, you might be able to
feed your VM's raw lvm partions on the DRBD system and not bother with
OCFS which would make life easier but I haven't looked into that.
Upside to this system is you don't have a NAS that can go down as a
single point failure.
For your offsite backup I'd then snapshot the machines and LVM's and
rsync them to your remote location.
rsync of the memory snapshot could consume a decent amount of bandwidth,
its probably going to be pretty volatile, if you can shutdown the guest
snapshot its disk then boot it back up again then the rsync traffic
should only be a little over the quantity of changes made to the disk IE
files added/changed, so not much more than your existing offsite backup
needs.
I'm using KVM for my virtuilisation and it seems to be working well,
very simple to use and the host has a full OS there to do whatever you
want with. Currently I run mysql on the host to get a bit more
performance out of the machines (with a ~20Gb database) and the
application servers in VM's on the same machine, with mysql replication
to pass the data between the hosts.
Nigel Allen wrote:
Greetings
I need to formulate a DRP for a customer and thought that I would ask
the slug for it's collective wisdom.
Customer currently has 3 x HP rackmounted servers runnning Centos 4.8
and a Dell rachmounted server running Windows Server 2003.
Backups are currently done to tape every night using Amanda.
Given the nature of the business and the reliance it places on
computer availability, we're looking at replication and virtualization
a a first step and off-site replication of some sort as step two.
First thought was to max out the memory on two of the servers, one for
normal running and one as a hot or warm standby, and the virtualize
all of the servers onto the two machines. An external consultant has
already suggested doing this with VMware, installing the ESXi
hypervisor on the two main servers and installing a NAS shared between
the two systems (hot and cold) so that if the hot server fails, we can
simply switch over to the cold server using the images from the NAS.
Couple of things concern me about this approach. The first is using
VMWare rather than a GPL solution. The second is where we would
install the NAS. Physically, the office space is all under one roof
but half the building has concrete floors and half has wooden. (The
hot server is in the wooden "main" office, while the cold server was
to go in the concrete floor area. There is also a firewall (a real
one) in between the two areas).
Questions:
1) Can anyone offer any gotcha's, regardless of how obvious they may
seem to you?
2) Is there a GPL solution that fit's this scenario? Even if it's not
a bare metal hypervisor and needs an O/S. Remember it has to virtuaize
both Server 2003 and CentOS
3) What's the minimum connection we would need between the NSA and and
the two servers sharing it?
4) What kind of speed/bandwidth should we be looking at for the
off-site replication.
I'll happily take anything else anyone would like to throw at this -
suggestions, reading matter etc - it's not an area of great expertise
for us having only paddled around the edges with Virtualbox.
TIA
Nigel.
--
SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/
Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
