Slow Win7 VM read/write performance when copying files.

[Brentsj]

I'm at a loss on this, any help would be appreciated.

ESXi 5.0.9, 768111
CPU: Intel(R) Xeon(R) CPU E31235 @ 3.20GHz
Memory: 16GB

I'm running as a VM Solaris 11 and Napp-it interface for the ZFS Pool. One of the folders is NFS that I have created a datastore on and using that for the Windows 7 virtual drives on.

When copying large files from a Windows 7 system that is NOT a VM, I average 106 (plus or minus a few) MB/Sec up or down.

The issue is on the Windows 7 VMs. I get really slow performance while copying files. From the shared folders I get 70 MB/sec upload, but download starts at 100 MB/sec and then very rapidly (within a 100MB or so of transfer) will drop to below 9 MB/sec.

What really has me confused is for testing I created a virtual drive on the datastore of the SSD that ESXi boots from and added a 5400 RPM SATA drive and created a datastore on it (both of these are devices are handled by ESXi, not the controller that's passed to Solaris) and transfer speeds are still really slow when copying a file between them.

Bonnie is giving me a benchmark of 296 MB/s sequential read, and 278 MB/s sequential write of the ZFS pool.

I have tried both E1000 and VMXNET 3 virtual network adapters -- there is no difference between the two.

I'm not sure if it's slow virtual disk read/write (mostly write) performance, or virtual network performance when copying files via the share, though with it being slow copying files from 2 datastores that aren't on the ZFS pool, I'm inclined to think it's not the virtual network settings.

Other than this issue, I'm really pleased with this setup.

 

[_Gea]

Bonnie is giving me a benchmark of 296 MB/s sequential read, and 278 MB/s sequential write of the ZFS pool.

I have tried both E1000 and VMXNET 3 virtual network adapters -- there is no difference between the two.

I'm not sure if it's slow virtual disk read/write (mostly write) performance, or virtual network performance when copying files via the share, though with it being slow copying files from 2 datastores that aren't on the ZFS pool, I'm inclined to think it's not the virtual network settings.

Other than this issue, I'm really pleased with this setup.

I suppose, its a sync-write problem.
ESXi requests sync writes on NFS datastores for better security.
(Every write must be commited from disk until the next can occur).

Try:
disable ZFS sync property (menu ZFS-folder) on your NFS shared ZFS folder
or add a ZIL drive to keep performace up with sync writes.

If you disable sync, up to 5s of last writes may be lost on power-failures.

 

[Brentsj]

I suppose, its a sync-write problem.
ESXi requests sync writes on NFS datastores for better security.
(Every write must be commited from disk until the next can occur).

Try:
disable ZFS sync property (menu ZFS-folder) on your NFS shared ZFS folder
or add a ZIL drive to keep performace up with sync writes.

If you disable sync, up to 5s of last writes may be lost on power-failures.

I never would have thought of that one, thank you!

With it set to standard, a 10GB transfer would eventually get to 8-10 MB/sec. With it disabled, the lowest it went was 67 MB/sec. Huge difference.

I'll do some research on how I can get a ZIL drive in my current setup.

Thanks again!