Re: SQLite and ext3 journalling mode

On 12/08/2010 02:02 PM, Miller, Mike (OS Dev) wrote:
>
>> -----Original Message-----
>> From: [email protected] [mailto:ext3-users-
>> [email protected]] On Behalf Of Ric Wheeler
>> Sent: Wednesday, December 08, 2010 11:08 AM
>> To: Richard Hipp
>> Cc: [email protected]
>> Subject: Re: SQLite and ext3 journalling mode
>>
>> On 12/08/2010 11:56 AM, Richard Hipp wrote:
>>>
>>> On Wed, Dec 8, 2010 at 11:25 AM, Ric Wheeler<[email protected]
>>> <mailto:[email protected]>>  wrote:
>>>
>>>      On 12/08/2010 06:52 AM, Dan Kennedy wrote:
>>>
>>>
>>>          Thanks. But to be clear, is data=ordered better than
>> data=writeback
>>>          wrt. data integrity following a power failure?
>>>
>>>          Regards,
>>>          Dan.
>>>
>>>
>>>      Data integrity can mean a couple of different things.
>>>
>>>      If you are file system meta-data centric (i.e., a file system
>> developer or
>>>      just worried about having to run fsck after a crash to repair the
>> file
>>>      system), then both options *should* be equivalent.
>>>
>>>      If you are one of those annoying users who define data integrity
>> to
>>>      include those annoying details like will my file have garbage in
>> it after
>>>      a crash that will make my DB or other app puke, then data ordered
>> is
>>>      clearly more robust.
>>>
>>>
>>> Thanks, Ric.  Yes, we are numbered among the "annoying users".  Based
>> on what
>>> you are telling us, we'll recommend that people use data=ordered,
>> barrier=1
> Just as an FYI, not all HW vendors enable the drive write cache especially on array controllers. In those cases barriers do nothing.
>
> -- mikem
>
>

Right - upstream has been working to make sure that we can default to barriers 
on and not see a performance hit for devices like arrays that don't need them ...

Ric