Hi Folks,
I'm wondering if something is doable - comments please:
I have a very specific situation where I'm trying to maintain a legacy
high-availability application running in a Xen VM (Linux DomU).
Current stack (per node, in a 2-node HA cluster):
Applications
VM (Linux DomU) --- auto failover to node 2 ----
DRBD ---- replicated to node 2 ----
LVM
md raid
Xen (Linux Dom0)
We're looking at migrating our infrastructure to an OpenSolaris base
(probably SmartOS), which will end up looking like this:
VM (Linux KVM or Zone) ------------auto failover ot node 2 -----
<synchronous replication> ----- to node 2 ----
ZFS (exporting a ZVOL)
KVM (or Zones)
SmartOS
The kicker, is that there is no available equivalent to DRBD for the
illumos ecosystem - hence, my thought is to mount the ZVOL block device
inside the 2 virtual machines, and use DRBD running on Linux inside the
pair of VMs to achieve storage replication.
Will DRBD run inside a virtual machine? Will it give any kind of
reasonable performance? Are there any serious gotchas to watch out for?
Three notes re. motivation and thinking:
- for all our other applications, we're doing application layer
replication (e.g., database sync) - but for smtp and list processing
this doesn't seem easily doable (too many queues and messages in flight,
asynchronously)
- looking to move from Linux for a number of reasons, but particularly ZFS
- looked at BSD, which has HAST as an equivalent of - virtualization is
a mixed bag (Xen on NetBSD, but not FreeBSD; KVM sort of, a new
hypervisor for FreeBSD), and ZFS is only stable on FreeBSD - can do some
things on FreeBSD, some on NetBSD, but not all on the same one - and
right now the illumos world seems to be gaining lot of momentum as the
alternative open-source Unix
Thanks very much,
Miles Fidelman
--
In theory, there is no difference between theory and practice.
In practice, there is. .... Yogi Berra
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