# XEN HVM - no caching on storage?



## icecoke (Sep 6, 2014)

I'm using a FreeBSD 10.0 with XENHVM Kernel support.

Testing the drive i/o of the xbd0 is quite poor. It seems absolutely no caching exists, as it's existing if I'm installing the same system on a physical machine.
`dmesg` shows this about xbd0 setting:


```
xbd0: 61440MB <Virtual Block Device> at device/vbd/768 on xenbusb_front0
xbd0: attaching as ada0
xbd0: features: write_barrier
xbd0: synchronize cache commands enabled.
```

Is this performance loss known/expected in a XENHVM environment? Is there a way to enable the known freebsd caching?

Any help is welcome!

Jimmy


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