Mailinglist Archive: opensuse (1784 mails)

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Re: [SLE] Realtime mirroring of a directory
  • From: bernie@xxxxxxxxxxxxxxxxxxxxxxx (Bernd Felsche)
  • Date: Thu, 7 Dec 2000 11:17:31 +0800 (WST)
  • Message-id: <200012070317.LAA11428@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>

From: Bernd Felsche <bernie@xxxxxxxxxxxxxxxxxxxxxxx>
Message-Id: <200012070317.LAA11428@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Date: Thu, 7 Dec 2000 11:17:31 +0800 (WST)
Subject: Re: [SLE] Realtime mirroring of a directory

Paul Hampton tapped away at the keyboard with:

> From: fountai@xxxxxxxxxxxxxxx [mailto:fountai@xxxxxxxxxxxxxxx]
>> > I'm running SuSe 6.4 on two web servers which are about to be
>> > load balanced. I wondered if anyone knew of a tool that would
>> > detect any file changes in my htdocs directory on one server,
>> > then replicate the changes on the other server. The current
>> > machines use Windows NT and Site Server for this process, but
>> > is there anything similar on Linux?

>> Do you actually need the mirroring for redundancy? If not
>> you could just export the files from the original machine
>> using NFS and have both machines use the same files. If
>> there's enough RAM in the second server the OS will cache
>> most of the data anyway and internal NFS network traffic
>> will be minimal.

> Unfortunately yes I need redundancy, I was hoping there was some kind of
> daemon available that monitored changes in a directory and then scp them
> automatically to the other servers. I want to avoid using cron as I really
> need actual realtime copying here...

Look at rsync. It can synchronise hosts quite nicely, even over low
bandwidth connections including ssh-encrypted ones. I've found an
rsync "server" running on a non-privileged port with its own
security domain to be sufficient for mirroring components of hosts.

I guess One could set up tripwire to work with rsync to get the
changes out ASAP.

But it's not "real time" because you see the changes on the "master"
before all the redundants have those changes by using some sort of
two-phase-commit. If you don't need that level of sophisitication,
then rsync should do OK.

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