Re: [boost] NuDB: A fast key/value insert-only database for SSD drives in C++11

Subject: Re: [boost] NuDB: A fast key/value insert-only database for SSD drives in C++11
From: Karen Shaeffer (shaeffer_at_[hidden])
Date: 2017-03-22 04:48:49

On Wed, Mar 22, 2017 at 05:13:31PM +1300, Gavin Lambert via Boost wrote:
> On 22/03/2017 16:08, Vinnie Falco via Boost wrote:
> >I think this can be unit tested, and I believe that NuDB's unit test
> >covers the case of power loss. I think we can agree that power loss on
> >a read is uninteresting (since it can't corrupt data). The unit test
> >models a power loss as a fatal error during a write. The test
> >exercises all possible fatal errors using an incremental approach (I
> >alluded to this in my previous message).
> 
> A power loss is more like a fatal error that fails to execute any subsequent
> clean-up code, so it might not be quite the same.

Agreed.

The hardware is losing power. The peripheral devices will likely not all lose
power simultaneously. The kernel is suffering a fatal crash. In my experience,
when you pull the power plug on a server, the execution of the kernel simply
ends without any trace of what happened. The application will suffer a fatal
error without any trace of it having happened.

Karen.
-- 
Karen Shaeffer                 The subconscious mind is driven by your deeply
Neuralscape Services           held beliefs -- not your deeply held desires.