UBIL design doc

[Brijesh Singh]

On Wed, May 12, 2010 at 3:31 PM, Artem Bityutskiy <dedekind1 at gmail.com> wrote:
> On Wed, 2010-05-12 at 15:19 +0530, Brijesh Singh wrote:
>> >> Any thing goes bad, normal scanning becomes recovery.
>> >> 5) Not sure if log is required in first place. But it could be an option.
>> >> Is that correct?
>> >
>> > No, at least I did not suggest you to get rid of the log. It is needed
>> > to handle unclean reboots.
>> Log is written for each EC or VID change.
>
> Yes, I understand.
>
>>  Frequency of log write is same as
>> the frequency of these headers.
>
> Right.
>
>>  In case we keep both, there will be one log
>> write penalty per write/erase.
>
> Yes, each time you write to an unmapped LEB, you write the VID header
> and a log entry.
>
>>  So write performance will drop considerably.
>
> Not sure about 'considerably'. This is to be tested. Keeping the headers
> means 1 additional write per peb_size bytes, right? Plus just after
> erase, EC header should be written. But this is the price you pay for
> robustness and compatibility.
>
> But again, it is very easy to switch off headers if this is needed,
> isn't it?
Yes.