HA/FT over WAN

[aiea96701]

I'm considering an inexpensive solution for a customer who desires "no downtime" replication between 2 servers existing between his production site in Michigan to an offsite DR site in New York over a WAN connection.  First of all, this is an option for him to consider along with other more expensive (but probably more suitable options).   He wants to see the wide range of options.   In any event, for this lesser option, I'm considering the following:

His existing setup is:

Production Servers are physical.  One is a file server containing JPG and other photo and video files.  He is in realestate.   The second is a sql server that he uses to manage a database that controls the pictures and videos. 

His desires:

If any of the two servers fails, he'd like to have replicated data  or servers available at his DR site that can "immediately" restore operations.  His preference is zero downtime but if that's not possible, he'll accept 15minutes or thereabouts downtime.

Lesser solution:

1.  virtualize the two production servers to ESXi hosts and Enterprise Licensing to set the two VMs up on HA/FT

2.  setup additional ESXi hosts at the DR site to be the target VMs for the production VMs and setup FT on them, as well

Note: I believe we can accomplish this requirement with only 2 ESXi hosts at production for redundancy  and can either go with two or a single ESXi host at the DR site (presuming that the objective is to restore the production host in short order.   Else, go with 2 ESXi hosts at the DR site.   I realizde that the optimum arrangement is 3 hosts but considering it is only for 2 VMs, I'm thinking 2 hosts will do fine.

Am looking for advice on this solution or other better alternatives.  

Thanks

[logiboy123]

What is the size of your VPN pipe?

What is your storage solution?

You would probably need to use a single subnet at both ends of the VPN connection.

So for FT across two hosts on a WAN link you will need to be running the management layer, VMotion, FT and storage across this pipe. Thats a big pipe for a WAN link.

[Hoschi201110141]

Hi

I not realy implement such a solution yet but let me tell you my minds:

1. HA => With HA you can do a Failover. But the Failover ist only the VMguest (CPU / Memory). I mean: When a Failover ocours... the VMguest maybe will start in New York and the VMDK-Files will reside in Michigan. I dont know the exact distance or Latency but this can realy be a Problem.

2. FT => Remember: FT supports only one vCPU. And the issue with the Latency is the same.. Each CPU Command and Memory Change must be submited and acknowledged from the "remote" Host.

I think a better solution for the needed Mechanism is SRM. Or when it must be cheaper an other Storagereplicated / Scripted solution.

Regards

Hoschi

[jamesbowling]

Another option and depending on bandwidth between the sites, you could use Veeam Replication to replicate to another cluster.  If a VM fails then you can fire up the replica at the DR site.  And you could automate this as well with a few scripts to check health and whatever, if fail then power-on replica.

[Gleed]

Chances of success are extremely low.  Even if you did get it to work it would be a very high maintenance and problematic solution.  Any kind of WAN hiccup would result in downtime, patching would be difficult, and you would constantly be fighting a need to resync everything over the WAN.

Not to mention it would not be supported as neither HA or FT are not supported across sites.

Some additional considerations:

1.  You would need to have a single VC instance with a single cluster that contains the ESX hosts from both sits.  Which site would you put VC?  How would you protect VC?

2.  FT requires 1Gbps logging network, you obviously won't get that over a WAN.

DR is expensive and I can understand wanting to explore options, but I would not advise trying to use HA/FT to craft a poor mans DR.  The proper solution for this is SRM.

Regards,

-Kyle

[idle-jam]

VMware FT requires 1Gbps (which is unlikely) and also VMware HA would required high bandwidth (this also needs the SAN to be mirroring each other like Lefthand Network Raid, EMC VPlex and etc.. very low latency too).

My suggest would be on OS cluster like XOSoft, DoubleTake or Neverfail