Holger Parplies <wb...@parplies.de> wrote on 10/06/2011 06:58:06 PM:
> Don't you feel uncomfortable about deduplication, too, then? After all,
it
> introduces a single point of failure for common data.
No. Dedupe is merely a side effect of a filesystem. Dedupe errors are no
different than any of 1,000 other possible filesystem errors. If I want
to defend against a dedupe error, I can do so by *also* protecting against
a filesystem error, too, and get dedupe safety for free.
Nearly all of my servers are virtualized today. These servers are backed
up two ways: a file-level backup and a snapshot-based backup. So I have
redundancy that protects against a *LOT* of failures. While it would be
harder to get a single file from a snapshot backup, it's very doable. So
I have that redundancy. Even if BackupPC were to decide to *maliciously*
destroy my data, no problem: my snapshots don't use BackupPC! :)
(The big reason for the snapshot backups is that Windows systems are *way*
easire bare-metal restored from a snapshot. But I get all the other
advantages, too.)
> If you can't get back
> your file from the most recent backup, because it has somehow been
corrupted,
> there's not much chance to get the same content from any other backup.
In
> other words, deduplication *is* a form of compression ;-).
That's true. But I would consider that "accidental" (or maybe incidental)
redundancy. It's still all on the same disk, with the same filesystem. I
consider dedupe a problem to defend against, but I also consider
filesystem (or disk!) failure a problem, too. I protect against *all* of
them, but not necessarily each individually.
Redundancy is a good thing.
(While we're on the subject, I've considered Les' argument that compressed
files take less space on the disk and are therefore less likely to be
corrupted before. It's true, but like dedupe errors, it's just *one*
possible failure--and to me, not a very likely one. It's not one worth
defending against by *itself*. Having uncompressed files makes, e.g.,
scanning a badly scrambled filesystem for salvagable data *much* easier.
When it comes to backup, I will almost *always* choose simple over fancy,
even if fancy gives me other advantages but not additional safety.)
Timothy J. Massey
Out of the Box Solutions, Inc.
Creative IT Solutions Made Simple!
http://www.OutOfTheBoxSolutions.com
tmas...@obscorp.com
22108 Harper Ave.
St. Clair Shores, MI 48080
Office: (800)750-4OBS (4627)
Cell: (586)945-8796
------------------------------------------------------------------------------
All of the data generated in your IT infrastructure is seriously valuable.
Why? It contains a definitive record of application performance, security
threats, fraudulent activity, and more. Splunk takes this data and makes
sense of it. IT sense. And common sense.
http://p.sf.net/sfu/splunk-d2dcopy2
_______________________________________________
BackupPC-users mailing list
BackupPC-users@lists.sourceforge.net
List: https://lists.sourceforge.net/lists/listinfo/backuppc-users
Wiki: http://backuppc.wiki.sourceforge.net
Project: http://backuppc.sourceforge.net/
