backup & low downtime for home network

Lennart Sorensen lsorense-1wCw9BSqJbv44Nm34jS7GywD8/FfD2ys at public.gmane.org
Thu Dec 6 16:04:14 UTC 2007


On Wed, Dec 05, 2007 at 09:17:43PM -0500, Robert Brockway wrote:
> Well "it depends".  For IDE there will be a performance gain for reads and
> writes if the two drives are on different channels.  If the two drives are
> on the same channel there may be a performance hit for reads and will be a
> performance hit for writes.  For SATA the situation should be better - I
> would expect both read and write performance gains.

If two disks are on the same channel with IDE running raid1 then you are
nuts.  If one drive fails it almost always takes down the channel in
which case you loose access to the raid anyhow.  Don't EVER install
raid1 across two disks on the same IDE channel.  You can run two raid1's
using two channels by having one disk from each raid on each channel.

> Absolutely.  Too many people assume mirroring offers some sort of
> backup-like reliability.  It does not.  Just imagine the result of an
> accidental rm: both copies of the data will be deleted.

Yep.  It's just protection against disk failures, although it is hence
very useful.

> Once planned out home backups don't have to be time consuming.  I have a
> cron job go over overnight which sshes to each box and dumps full or
> incremental backups to a usd HDD.  I have 5x500GB USB HDDs and these are
> rotated offsite periodically.

I meant restoring a system due to disk failure from backup takes a lot
of time, compared to having raid1 to deal with that.

> The key is _off site_ backups.  Keep backups of all your important data
> and keep at least one copy offsite at all times.

I keep meaning to start doing rsync mirrors between my own machine and
my parents (in both directions).  Seems like it would be a good
solution.

> The cost of USB HDDs is low compared to what an offsite backup offers you.
> 
> As to where to keep an offsite backup - a workplace may be fine.  If you 
> work at home then arrange to swap offsite backups with a trusted friend. 
> Be very very careful about encrypting backups (and filesystems for that 
> matter).  You can't just "get the password reset" if you forget your 
> passphrase or lose the private key.

I don't encrypt backups.  Just protect them as well as you would the
system you are backing up.  Now for those people who encrypt their main
filesystem, well sure you should encrypt the backup too.

--
Len Sorensen
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