HAST slowness ?

[Mikolaj Golub]

On Thu, Jul 31, 2014 at 05:20:34PM -0400, Mike Tancsa wrote:
> I am trying to setup my first HAST setup and for some reason, traffic 
> sync seems to be really slow.  If I do something simple like
> 
> 
> #dd if=/dev/zero of=/hastvirt/test count=2000 bs=1024k
> 
> on the primary box, traffic on the secondary never gets much beyond a 
> Mb/s ?!?!
> 
> iperf and netrate show I can pretty well saturate across the link. There 
> are no errors and the underlying NICs are both at gigabit with no other 
> traffic. Everything seems happy, just very slow to sync. Any idea where 
> to start debugging ?

It looks you are writing to a file-system, not directly to HAST
device? What is this FS? I see two HAST devices? Are they combined in
one FS? How? What if you write directly to a HAST device instead?

Also note, "hole" compression is enabled by default, so your test with
copying zero blocks is not very good. You might be limited here by
RTT, because in memsync mode, on every "compressed" block sent HAST
waits for response before proceeding with the next block.

-- 
Mikolaj Golub