"Tyler J. Wagner" <[email protected]> wrote on 10/25/2012 09:14:47 AM:
> On 2012-10-25 14:10, Bowie Bailey wrote:
> > On 10/24/2012 12:41 PM, dixieadmin wrote:
> >> I am currently using BackupPC 3.2.1 on SME Server 8.0. I wanted
> to know if there is a correct procedure for using 2 different
> external harddrives as a backup source and to interchange them weekly?
> >
> > "interchange them weekly" ... Are you referring to having a 2-drive
> > mirror and replacing one weekly? Or having one drive connected at a
> > time and swapping them out weekly? Or having both drives connected
and
> > swapping both out for 2 different drives weekly?
>
> Because of the pool model that BackupPC uses for storage, there are only
> two useful methods for using two different external drives:
>
> 1. Use RAID and remove one member periodically, to take offsite. This is
> best done with 3 drives, actually.
>
> 2. Use the external drives as a target for ArchiveHost, and dump
occasional
> tarballs of each host to them. This is OK for emergency restore but
won't
> give you a working BackupPC server if you want that.
Also, keep in mind that the original question shows a fundamental lack of
understanding in the way BackupPC works. BackupPC is *NOT* a simple
replacement for a tape drive. Swapping the entire pool weekly will
undermine the way BackupPC works: it's not designed for that. And using
preconceived ideas of traditional backup to shape the way BacukpPC works
is not a path that leads to success.
For BackupPC to work effectively, the pool stays in place permanently,
100% of the time. You do not "interchange" anything inside of BackupPC at
all, with any frequency. Of course, off-site backups are important, even
essential. This is *NOT* achieved by swapping pools. It's achieved by
one of three ways:
1) Constantly mirroring the pool and occasionally breaking the mirror to
take it off-site. (Option 1 above). A variation of this would be to take
the pool down and make a copy of it, then bring it back up (or use LVM
snapshots to reduce the downtime). This variation is left as an exercise
for the reader: there are a *lot* of unexpected details in that answer:
problems with file-level copy will most likely require block-level copies,
LVM snapshots present performance and reliability issues, etc.
2) Exporting a single copy of a specific backup to a removable destination
and moving that off-site. (Option 2 above). A variation of this would be
to make the destination for the archive a remote filesystem already
off-site, and there is no physical movement at all.
There is a third option that was not mentioned:
3) Have two BackupPC systems that *both* back up the same hosts in
parallel. A variation of this would have the BackupPC servers in
different physical locations. This variation just about requires the use
of rsync, and even then is not always practical (if the data changes per
day/week/whatever are too vast, the bandwidth between them too limited, or
there is simply too much data to be able to back it all up twice in a
reasonable amount of time).
Tim Massey
Out of the Box Solutions, Inc.
Creative IT Solutions Made Simple!
http://www.OutOfTheBoxSolutions.com
[email protected]
22108 Harper Ave.
St. Clair Shores, MI 48080
Office: (800)750-4OBS (4627)
Cell: (586)945-8796
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