Re: [Moosefs-users] Backing up MFS metadata

[Michał B. <mic...@ge...>]

 

 

From: Stas Oskin [mailto:sta...@gm...] 
Sent: Friday, July 30, 2010 12:44 AM
To: Roast
Cc: moosefs-users; Michał Borychowski
Subject: Re: [Moosefs-users] Backing up MFS metadata

 

Hi.

 
Getting back to this to clarify the matter:

 

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.


According to article only "0" file contains the ongoing info, so why the "1"
is needed?
How often the checkpoint files are updated?

[MB] In most cases 0 would be enough. But there may happen some "border"
cases and it is more secure to use also file 1.

 

 

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. 


Perhaps I can put metaloggers on the chunkservers? How much resources the
metalogger takes? 

[MB] You can easily put a metalogger process on a chunkserver. The resources
needed for metalogger are not very high and I am sure your chunkservers have
quite a lot spare processor power.

 

Regards

Michał