Re: [Moosefs-users] Backing up MFS metadata

[Michał B. <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.