Offsite Replication

Jared Klett jared at
Mon Jun 25 20:22:59 UTC 2007

It's really cool to see this subject resurrected - I believe it was
first brought up a while ago with a discussion of  support for Amazon S3
as a "store but don't serve" device.

I would call such a device state "storeonly" or "writeonly" or some
non-compound word. :)

-----Original Message-----
From: mogilefs-bounces at
[mailto:mogilefs-bounces at] On Behalf Of Brad Fitzpatrick
Sent: Monday, June 25, 2007 4:19 PM
To: Erik Osterman
Cc: mogilefs at
Subject: Re: Offsite Replication

You should be able to write a ReplicationPolicy subclass for it.

The perhaps non-existent part is marking a device as "alive to get new
files from the replicator, but not alive enough to serve traffic".  We
have the opposite of that recently (drain), which serves traffic, but
doesn't get new files, and adding drain supported made us abstract out
all the state stuff, so adding new states is easy.  Wonder what we'd
call that state... so far we have alive, down, dead, readonly, drain ...

The other option is doing backups outside of MogileFS, just copying FID
#1 offsite, then #2, then #3... since it's all sequential, your backup
software can resume where it left off quite easily.

I'd love to get the "get files but don't serve from them" support into
the core, though.  Seems useful.

On Fri, 22 Jun 2007, Erik Osterman wrote:

> We would like to have files replicated automatically to offsite
> These offsite devices would not and should not be used by MogileFS 
> clients;  they should only be used as a remote backup. Has it been 
> suggested or is there otherwise a way to accomplish this with the 
> current (svn) version of MogileFS?
> Best,
> Erik Osterman

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