Backups were fast, now slow. Hardware issue?

[ScotofMKE]

I have two VMWare ESXi 4.1 hosts, and am backing up the guests from a physical server over a 1 Gbps line. The guests are all on direct attached storage. A couple weeks ago the backups on one host began to crawl. For example, a 20 minute backup now takes 5 hours or so. This problem only occurs for the guests on one host, whereas the other host is completely fine. Both servers use the same switches. The server that is slow to backup runs the VMs without any problem at all, and the vSphere client displays no errors or anything other than "normal" for the hardware status. Any idea whatsoever of what could be causing the problem?

[Vitaliy S.]

Hi Scot,

Please tell us the bottleneck stats for your jobs (available in the job properties window by right-clicking the job and selecting Statistics). Also is CBT enabled for the VMs that crawl?

Thanks!

[ScotofMKE]

The bottleneck stats are 99% source and 2% proxy. CBT is disabled.

[Gostev]

What is the processing mode used? Sounds like direct SAN connection or hot add is no longer available, and backup goes over the network.

[ScotofMKE]

Sorry, I'm not sure what you mean by "processing mode".

The odd thing about all this is that the backups on another VM host run at a fast rate. Both servers use the same switches.

[tsightler]

Why is CBT disabled? That can cause a huge performance drop.

[Vitaliy S.]

Sorry, I'm not sure what you mean by "processing mode".

Can you please clarify what mode direct SAN, HotAdd or Network is used to backup your VMs? You can check this info in the corresponding job session statistics (just select the VM you are interested in).

[ScotofMKE]

I'm not seeing those options. Below is a screenshot of what I do see.

[ScotofMKE]

Clarification on the CBT. Veeam reports "Changed block tracking is disabled", but a check of the parameters for the VMs shows that it is actually enabled. Odd, isn't it?

[Vitaliy S.]

1. Please see our User Guide (page 288) to locate the information about processing mode for your VMs.
2. Here is a couple of links about CBT, might be useful: CBT requirements and How to reset CBT