Dutch VMUG meeting 2008 part 2

Lefthand Networks – John Spiers

John Spiers co-founder of Lefthand Networks (LHN) elaborated about Virtual SAN’s in the Virtual Data Center. He started to mention the acquisition of Lefthand Networks by HP and showing a HP branded presentation. LHN was founded in 1999 and it was then they started selling ISCSI-based storage, even before the protocol was formally standardized, according to John Spiers.

LHN addresses problems like the fact that servers nowadays are mapped to static resources and the demand of virtual performance for ports, zones and RAID groups is rising, etc. How does LHN address these problems.
LHN has five (5) main features:

  1. Storage Clustering
  2. Network Raid
  3. Thin Provisioning
  4. Snapshots
  5. Remote Copy (Disaster Recovery)

I was sitting next to a former colleague/customer, and while listening I remembered we recently discussed the concept of High Available an physically separated  Sites (+50 km) and the ability to vMotion a VM from one site to another. Almost every requirement was met to make it work except for the storage.

And I mean really high available and not a DR solution. When the first DC fails the other DC has to take over using HA or the new Fault Tolerance feature.

The discussion focused on the storage side and questions like how to make the storage high available in a way that the storage is available instantly in the other datacenter without having to act on it.

First another colleague mentioned Storage vMotion. We concluded that using Storage vMotion creates a low available solution (takes time to copy data with SvMotion) and you will end up failovering by hand if you’re lucky to be able to do that in case of failures. So for this scenario it’s a no go.

Site Recovery Manager (with underlying storage replication) is not a solution either, using SRM you still have to get the LUN out of replication mode to use it (make it active). Besides this, SRM is not an High Available solution it is a Disaster Recovery Solution and it takes downtime as granted. Someone has to push the button to failover with SRM, so another manual factor.

During this session another option popped up. Lefthand Networks offers a so called Network Raid, with the Network Raid it is possible to use a single SAN across (physically separated) sites. RAID 0 mirroring might be a worth a shot. Downside of this can be the network latency, this must be less than 5 ms. Also hardware dependency may be something to keep in mind

VirtualGeek wrote an interesting article about Storage vMotion partly related to the discussion mention above: http://virtualgeek.typepad.com/virtual_geek/2008/12/real-world-experiences-using-storage-vmotion.html#more

Then the session and the discussion ended… 

Comments are welcome.

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