raw disk issues

[cornbread]

I have a SSD that I followed this guide: http://tuxnetworks.blogspot.com/2010/05 ... albox.html to make it accessible directly to the guest.

I don't have differencing turned on but when I put files on there the write speed is only 20MB/s. If I put files on it from the host I get 60+MB/s.

Also once a file is put on there from the host or from the guest it is not accessible to the other!

Help would be appreciated!

[mpack]

You are implementing a DIY shared folder aren't you? Why on earth would you use raw disk access for that instead of just creating a network (SAMBA) share with your Ubuntu host?

Anyway, raw disk access does not mean direct disk access. It is still accessed via a virtual controller so there is no speed advantage. The only "advantage" is that you are accessing the same filesystem as the host: which is of course dangerous and would no doubt result in corruption if you actually managed to bypass the protections.

As the manual says, raw disk access is an expert level feature. This means that if you need to ask for help in getting it working then you probably shouldn't be using it. Use a shared folder (located on the SSD drive) instead - either a GA shared folder or a network share.

[cornbread]

shares speed only reaches 20MB/s! That is horrible performance!

If the performance were there I wouldn't be trying crazy options.

How can i fix the abysmal internal or network share speed?

[mpack]

shares speed only reaches 20MB/s!

You mean with GA shared folders? Yes, performance with that is often quite poor, I don't really know why - though I should mention that my experience is mostly with Windows as both guest and host. However performance with a true network share is much better (same caveat applies). I suggest a VirtIO-net share with "Host Only Ethernet Adapter" network mode, which will also allow the use of a fixed IP address.