Xen users - Aug 2012 - Windows DomU with SSDs

Hi Everyone,

We are thinking of venturing into the world of hosting Windows DomUs on our Xen
infrastructure. As Windows generally requires a lot more IOPS than Linux does,
we are trying to do everything we can to improve performance.

While using SSDs would solve the IOPS problem, SSDs suffer from limited write
cycles. So, we have the idea of using Flashcache from Facebook to use a single
SSD as a cache in write-through mode, along with spindle drives in RAID10.

My questions to the community are:

1) What are the general views of using SSDs in a Xen environment? All of our
guests are "untrusted". Is this just generally a bad idea?

2) Does anyone have any experience of using Flashcache? Are there any potential
issues that someone has come across?

Thanks

> Hi Everyone,
> 
> We are thinking of venturing into the world of hosting Windows DomUs on
> our Xen infrastructure. As Windows generally requires a lot more IOPS than
> Linux does, we are trying to do everything we can to improve performance.
> 
> While using SSDs would solve the IOPS problem, SSDs suffer from limited
> write cycles. So, we have the idea of using Flashcache from Facebook to use
> a single SSD as a cache in write-through mode, along with spindle drives in
> RAID10.
> 
> My questions to the community are:
> 
> 1) What are the general views of using SSDs in a Xen environment? All of
our
> guests are "untrusted". Is this just generally a bad idea?
> 
> 2) Does anyone have any experience of using Flashcache? Are there any
> potential issues that someone has come across?
> 
Bcache (http://bcache.evilpiepirate.org/ ) is another project that does the same
sort of thing as flashcache. Someone has put together some benchmarks comparing
the two, although obviously they might not reflect your workloads...

http://www.accelcloud.com/2012/04/18/linux-flashcache-and-bcache-performance-testing/

James