Backups with 9-STABLE -- Options?

[Karl Denninger]

On 6/10/2012 10:13 AM, Adam Strohl wrote:
> On 6/10/2012 3:08, Karl Denninger wrote:
>> With SU+J as the default filesystem, what options actually WORK now?
>>
>> 1. Dump "L" will NOT -- it doesn't hang any more but now just bitches
>> and refuses to run.  I suppose that beats a hang....
>
> Heh, yeah that is improved from what it did before ;D
>
>> 2. Dump without "L" and take your chances?  What risks am I running by
>> doing this on a running system?
>
> Depends on what is running and how it does file writes.  For example
> SQL DB storage engines are unlikely to do well (ie; the restore will
> be corrupted if there are changes during the process).  Something like
> CouchDB though which is "always consistent on disk" probably wouldn't
> care.
Well, backup with snapshots don't do well EITHER on a database unless
you can snapshot BOTH the dbms data store(s) and the transaction log
store(s) /*at the exact same instant*/.  If you cannot then you're
asking for trouble and are likely to get it.  But I've dealt with that
particular "gotcha" problem in a different way for the DBMS I use
(Postgresql)
>
> Past specific applications (or user activity) the inherent risk is
> unpredictable usefulness of your backups.  Since you're doing backups
> as a safeguard (and are very likely your last hope if things really go
> wrong) you don't want to find out that a key piece corrupted or
> missing entirely due to files moving around during the dump when you
> end up needing it.
Yeah, that's the problem.
>> 3.  Other?
>>
>> Dump has been the canonical means of backing up... forever.  And it
>> still is claimed to be the canonical means in the documentation.
>>
>> So what options do we have now that actually work -- is there now a new
>> "canonical" backup method that is recommended?
>
> My solution is to turn off journals for any build.   Dump is a great
> tool (especially when scripted) and is very efficient.
>
> And as neat as journals are, backups using dump with snapshots is way
> more valuable and important in my book.
>
> My .02.

So basically what you're saying is that SU+J leaves you exposed to
having no real backup option that provides a rational guarantee of the
ability to restore the backup taken.

Yet this was made the default.... why?

-- 
-- Karl Denninger
/The Market Ticker ®/ <http://market-ticker.org>
Cuda Systems LLC