Best mode for replication over WAN?

[pufferdude]

I am trying out replication for the first time... the goal is to get a critical Exchange VM replicated to our remote location across a 6Mbps VPN link. My question is which backup mode is best for this scenario? "VMware Storage API / Network" or "Network replication"? I'm not sure I understand the real differences between the two, and if only one is appropriate or if either would end up working equally well.

Advice?

[Gostev]

What ESX version do you use, and what storage (local or shared)?

[pufferdude]

At the main location I have ESX4 hosts connected to a iSCSI SAN (and use vStorage SAN mode to back up all VMs to another array). At the remote site I want to replicate a couple VMs to I have a single ESX4 host with 600GB local storage.

Now that I think about this some more, it seems that the only logical option is the vStorage API network mode, so that I can take advantage of CBT. Is that correct? I assume CBT is not an option when using veeam's network mode and there's no way the benefits of compression would outweigh CBT... am I right?

[Gostev]

That is correct. Any vStorage API mode will leverage changed block tracking, so that it is best for ESX4 in all cases. "SAN" and "Virtual Appliance" vStorage API options will provide better speed than "Network" option, because they are not subject of slow ESX4 service console disk read performance.

[b.thoele]

Could you a elaborate a little more? Please confirm that my statements are true.

For hosts with direct attach storage replicating across the WAN running pre ESX 4 your best option is network replication mode because it processes the data stream directly from one ESX host to another?

For hosts with direct attached storage running ESX 4 is your best option still Veeam network replication?

For those who have been running network replication with ESX 3.X with direct attached storage what changes can be made to maximize performance? Would the answer be upgrade from ESX 3.X to 4 and switch to a different backup mode?

What are your options if you have all the newest versions Veeam 4.1 and ESX 4 but you're running direct attached storage?
Vstorage API SAN failover NO?
Vstorage API SAN only NO?
vStorage API Network Yes? But not WAN compatible? NO?
vStorage API Virtual appliance NO? You most have a SAN or shared storage.

Network replication Yes? But it's slow because the whole VM has to be processed every job?


Is vStorage API WAN compatible, My remote ESX host wants to connect using my local backup server local IP. What did I do that the remote host is trying to use a local IP and not a hostname?

Constructing rollback file name
Cannot connect to server [192.168.1.5:]

[Gostev]

For hosts with direct attach storage replicating across the WAN running pre ESX 4 your best option is network replication mode because it processes the data stream directly from one ESX host to another?

Yes. It is best in this case mostly because of network traffic compression. Direct data stream by itself does not give much performance benefits.

For hosts with direct attached storage running ESX 4 is your best option still Veeam network replication?

No, definitely vStorage API : with "Network" or "Virtual Appliance" option (if your VMware license includes iSCSI Hot-Add feature).

For those how have been running network replication with ESX 3.X what changes can be made to maximize performance? Would the answer be upgrade from ESX 3.X to 4 and switch to a different backup mode?

Yes, switch to ESX4, and use vStorage API mode - in this setup, you can achieve near-CDP replication. Preferably, also find acceptable way to overcome issue with slow ESX4 slow network processing: either use shared storage and SAN option; or keep local storage - but get VMware license which allows for iSCSI Hot-Add to use virtual appliance mode. Could as well stay with local storage and vStorage Network option, processing speed will still be acceptable on incremental runs due to the changed block tracking (around 100MB/s on average, depending of amount of changes since last pass).

[b.thoele]

To follow up for those who are interested.

If you are running direct attached storage(das) to das with ESX 4 with Veeam replication set to VStorage API virtual appliance mode you most have a VMWare feature called hot-add included in Vspere 4 advananced licening.
Here is a product feature comparision to help people understand where they need to get to. It's VMWare KB 1010579

Comparison of product offerings for vSphere 4.0 and VMware Infrastructure 3.X

http://kb.vmware.com/selfservice/micros ... 2055276538

For those who don't have a SAN are there any options for a fake SAN? Could you run Openfiler or http://www.starwindsoftware.com/veeam as a VM for the perposes of vStorage API?

[b.thoele]

I have been using Veeam network replication between two sites that are behind a NAT without site to site VPN. I did this by setting up both internal and Internet DNS points for hostnames and by creating something like 6 firewall rules to allow traffic to flow. This has been working fine.

As I try to run replication using vStorage API in network mode I have problems with my remote client not being able to resolve the local IP of the veeambackup.exe on the backup console on our local network. Has anyone figured out a way to do this without a site to site VPN? Is there a hack to be able tell the remote client a resolvable hostname? Or could some tell me some static routering magic to get that traffic back to our site?

Thanks always.

[pufferdude]

You could always just put the hotname/IP you want in the hosts file of the local machine. Hosts always trumps DNS.