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From Patrick Hunt <ph...@apache.org>
Subject Re: Backups
Date Thu, 19 Jan 2012 18:24:25 GMT
I don't think we have a "backup" story today. "copy the datadir" is
not a great story. You could for example get snaps/txnlogs that are
only partially written. Now this is fine from the perspective that a
ZK server can recover from that, but EOD it's pretty ugly. Also
requires you to copy the entire datadir, and not just the most recent
"known good" snap/txnlog file(s). Not to mention the issue we talked
about before - you're getting a copy from some unknown point in time,
largely defined by how up to date the server is with the leader. It
seems to me that if we really want to support backing up the servers
we need a better story than this. Perhaps some tool which can ask a
server to generate a "backup" (but only if it's reasonably up to date
with the leader, most importantly that it's actually active in the
ensemble, etc...), ensure that the file creation happened successfully
(ie verify the output files), then copy that result, rather than the
"copy the datadir" approach we have today.


On Thu, Jan 19, 2012 at 10:16 AM, Jordan Zimmerman
<jzimmerman@netflix.com> wrote:
> Ted - are you referring to my original plan to backup the transaction logs
> or the new idea of backing up certain nodes?
> -JZ
> On 1/19/12 10:11 AM, "Ted Dunning" <ted.dunning@gmail.com> wrote:
>>What Jordan is doing would allow backups without special storage devices
>>and, with good backup of the log, would allow nearly current recovery in
>>the event of catastrophic loss.  Yes, this loses some durability, but it
>>still very desirable.

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