Re: [PATCH] barrier support for other md/raid levels

[Ric Wheeler <rwheeler@redhat.com>]

On 09/18/2009 02:38 PM, Greg Freemyer wrote:
> On Fri, Sep 18, 2009 at 2:28 PM, Ric Wheeler<rwheeler@redhat.com>  wrote:
>    
>> On 09/18/2009 02:19 PM, Chris Green wrote:
>>      
>>> It seems like what you'd need to robustly test barriers is some sort of
>>> barrier-supporting loopback device, which
>>> acted correctly with barriers, but had worst-case behavior without them
>>> (buffering things for random arbitrarily long periods of time,
>>> performing all operations in random order, etc).
>>>
>>>
>>>
>>>        
>> I think that it is pretty easy to get corruption (defined as fsck issues) if
>> we have non-working barriers and do power fail testing. It is a bit tricky
>> to automate that though but we are working on it,
>>
>> ric
>>      
> Ric,
>
> You are probably already using them to help automate the process, but
> if you don't know computer controlled power switches are pretty
> standard fare for computer clusters.  I'm sure Redhat's cluster team
> has some.
>
> And the cluster team may also have scripts to test things like
> unexpected power fails to one of the cluster members.  It may not be
> too hard to adjust those scripts to handle your needs.
>
> Greg
>    

We definitely have those and do similar testing. It is a matter of 
getting a good work load and automating the regression testing.

Chris's earlier test is a great starting point, HP has tests (hazard) 
that do really mean things to storage as well.

Just need to get time to get it all going :-)

ric