Physical Proxy but Virtual WAN Accelerator?

[jbarrow.viracoribt]

Thinking of adding WAN Accelerators to our environment. I was wondering if there was any disadvantage to using a VM as the WAN accelerator cache? Right now we have a physical proxy that pulls data via fiber channel and sends that data directly to the target side physical proxy. If we add in a VM WAN accelerator, will it slow things down since the proxy has to communicate with the accelerator VM during the job run? Also, when a WAN accelerator is in use, is it actually transferring the data or is the proxy still sending the data to the target site?

[foggy]

Jonathan, first of all, we're talking about replication jobs, right?

Basically, if direct mode is used, data is being transferred between proxy servers. In case of WAN accelerated transfer, the data flow is the following: source storage -> source proxy -> source WAN -> target WAN -> target proxy -> target datastore. So, in case proxy and WAN accelerator are deployed on different servers, there's another leg for data to pass.

That said, what is the link you have between locations and what is the current bottleneck reported by the replication job in question? Depending on that, you may or may not need WAN accelerators to be involved.

[jbarrow.viracoribt]

Yes, we're talking about replication jobs.

The link we have between sites is a 20-50Mbps circuit but we have Veeam traffic throttled to 30Mbps so we don't saturate the lines.

Current bottleneck (no accelerators used):
Source: 14%
Proxy: 2%
Network: 77%
Target: 4%

[foggy]

Using WAN accelerators looks reasonable in your case. Consider deploying them on the proxy servers though, if they meet the combined system requirements and have disks fast enough.

[jbarrow.viracoribt]

Are there any situations where a WAN accelerator would be a bad idea or slow things down or should it always be viewed as a boon to efficiency?

[foggy]

Since WAN accelerators are effectively trading disk I/O for WAN bandwidth savings, slower disks paired with decent link would eliminate the improvements they might provide. Anyway, only actual tests will show the benefit of their usage in each particular case.

[dellock6]

The area where a WAN accelerator will "always" make sense is to reduce bandwidth consumption, I've seen it deployed even with bandwidth larget than the usual limit of 125-150 MBs in order to free a percentage of it for other traffic. But as Alexander said, there's always a trade with IOPS, so you better check what are your requirements in this area.