Re: [Moosefs-users] Backing up MFS metadata

[Roast <zha...@gm...>]

Another question.

Does master server sync the change log to metalogger server in real time?

And if so, we can restore the full meta info from the metalogger server. Am
I right?

2010/7/15 Michał Borychowski <mic...@ge...>

>  You can backup changelog files (you would need just the two newest ones –
> “0” and “1”). You can make these backups even every minute. So you can have
> potentially lost information for about 1-2 minutes.
>
>
>
> But the question is – why to back up changelogs manually? Metalogger
> machines are dedicated to this. You can have as many metalogger machines on
> the network as you like. And metalogger process can be run on any computer,
> even an older one.
>
>
>
>
>
> Regards
>
> Michał
>
>
>
>
>
>
>
> *From:* Stas Oskin [mailto:sta...@gm...]
> *Sent:* Friday, July 09, 2010 2:27 PM
> *To:* Fabien Germain
> *Cc:* moo...@li...; Michał Borychowski
> *Subject:* Re: [Moosefs-users] Backing up MFS metadata
>
>
>
> Hi.
>
>
> 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?
>
> Regards.
>
>
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