esxi FreeNAS and windows vm's - strange bottleneck in data transfer

[pieter-jan goeman]

Hi guys,

I followed the freenas guide to setup freenas as vm on an esxi server.
the freenas server gets 16 gigs of ecc ram, 2 cpu cores from a xeon 5520, and passthrough to a hba card with 6 * 2tb drives.
this works perfect.
the freenas server has a share that is used by esxi as datastore, on this share I install other vm's
for example one windows vm.
now the problem comes with this windows vm, it seems to work great, but when I copy files from another freenas share, it first goes very fast, like 150 MBps, and after a few seconds, drops to like 5 MBps.
In task manager in windows, I see that disk is at 100% at that moment.

I hope we can find a sollution here!

thanks!

 

[m0nkey_]

How is your dataset mounted? iSCSI or NFS?

 

[pieter-jan goeman]

NFS mounted!

 

[Stux]

So, you're copying files to your windows disk, which is a vmdk on an nfs share?

 

[pieter-jan goeman]

So, you're copying files to your windows disk, which is a vmdk on an nfs share?

That's right!

Sent from my ONEPLUS A3003 using Tapatalk

 

[Stux]

You probably need a SLOG device. ESXi forces sync writes on NFS.

Here is me running some tests from a Mac OS instance. Same thing really.

https://forums.freenas.org/index.php?threads/testing-the-benefits-of-slog-using-a-ram-disk.56561/

 

[pieter-jan goeman]

You probably need a SLOG device. ESXi forces sync writes on NFS.

Here is me running some tests from a Mac OS instance. Same thing really.

https://forums.freenas.org/index.php?threads/testing-the-benefits-of-slog-using-a-ram-disk.56561/

I see, this is new to me, I'll have to look into it! thanks!