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: Olaf van der Spek (ml_at_[hidden])
Date: 2017-03-22 08:01:40

On Wed, Mar 22, 2017 at 5:13 AM, Gavin Lambert via Boost
<boost_at_[hidden]> 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.

Recovery obviously runs on the next power on. ;)

> There are also more pathological cases such as where a write has been
> partially successful and done some subset of increasing the file size,
> zeroing the extra file space, and writing some subset of the intended data.
> So it's not necessarily that data is missing; there might be invalid data in
> its place.

Do modern FS still allow that to happen? I guess some do..
Don't (log) records contain a checksum to guard against this?

-- 
Olaf