ESXI 5.5 transfer speeds

[azler]

I am having some issues with server 2012 and file transfers.

When I try to copy a large file to the server 10GB it completes about 47% at 100Mb/s and then drops off to practically nothing and hangs there. (see screen shot.)

The data store is 4x 3TB in raid 5, 16 GB ram in the host (12 in the VM).

Nic teaming is enabled.

I also tried a windows 2008 R2 server and this had exactly the same issue pointing me in the direction of it being the ESXI host.

[King_Robert]

if you have speed issue then please verify these things in your environment:

·  VMware recommends using multiple NICs on the associated virtual switch to increase the overall network capacity for portgroups that contain

    many virtual machines or several virtual machines that are very active on the network.

·  Verify the speed and duplex settings of the installed network adapters..

·  Verify that the portgroup and virtual switch are not configured for promiscuous mode..

·  Verify the integrity of the physical network adapters.

·  Verify that your host is not overloaded. Networking relies on available processor resources. If the CPUs on the host are being used at capacity, 

     network performance suffers.

·  Verify that you have chosen the appropriate network driver for your virtual machine based on your needs..

[a_p_]

Some thoughts:

• a RAID 5 set with 3 disks is one of the slowest configuration you can have due to the way RAID 5 works, as each write locks two disks (data and parity)
• you most likely don't have a RAID controller which has write-cache to allow operation in write-back mode. Without write cache the controller works in write-trough mode where each write operation has to be committed from the disk(s) rather than the cache. ESXi doesn't do write caching on the Hypervisor level.
• the high speed at the beginning is likely due to OS (Windows) guest OS caching. Once the cache is full, the writes need to go to the disk (write-through)

André

[azler]

King_Robert:

I have checked everything you have stated and the host is setup correctly.

A.p:

It is a P410 with a 256 write cache (No battery) & 4 x 3TB SATA drives. (Not the quickest but I have not come across this issue in the past.)

Is there anyway to increase the windows cache? to improve performance?

Rob

[a_p_]

I'm not sure how much you can increase performance by changing guest OS settings. I'd suggest you consider getting the 1GB Flash Backed (FBWC) cache upgrade for the P410 controller.

André

[taylorb]

a P410 without a cache battery (or flash) backup will not enable write caching, but should enable read caching.    However, even with a slow, uncached RAID 5 on 4x7200 RPM disks, you should see at least 100 MB/s write speed for a straight sequential file copy.  Something is definitely amiss for you to hit under 10MB/s.   To rule out disk issue, you could try creating two virtual disks in the same VM on that array and doing a non-network copy from one disk to the other.  I suspect you'll get at least 80MB/s or faster in normal situations

What is your network configuration on the ESXi host?   Due you have any weird issues like duplex or speed negotiation mismatch?    What virtual NIC type have you selected for the VM?  Do you have VMware tools and the right NIC driver installed?

azler wrote:

A.p:

It is a P410 with a 256 write cache (No battery) & 4 x 3TB SATA drives. (Not the quickest but I have not come across this issue in the past.)