Re: [Moosefs-users] Backing up MFS metadata

[Fabien G. <fab...@gm...>]

Hi,

On Fri, Jul 9, 2010 at 2:27 PM, Stas Oskin <sta...@gm...> wrote:

> As for the time it takes, it depends on the number of chunks you have, and
>> the hardware server you use (CPU + HDD speed). For example in our case (15
>> million chunks, 6 GB of metadata), it takes between 1 and 2 minutes on a
>> Xeon processor.
>>
>
> I actually meant, how much time backwards could be recovered by replaying
> all the logs?
>
> Michael said that backup log is created every hour so up to 1.5 hour can be
> potentially lost.
> If all the logs are replayed, can the data be consistent up to the moment
> of crash?
>

By default, logs are written to disk every 1 hour. So you can loose up to 1
hour if your mfsmaster crashes just before a new disk flush occurs
(everything is stored in memory for performance reasons :
http://www.moosefs.org/moosefs-faq.html#cluster).


Fabien