OFF: Drives and backups (was: Re: +++stop press+++advertising aid item french hassan+++one man isolator+++)

[Mary Sullivan]

You're way over my head, I simply need to find out how to back up.  Chris ws
horrified when he saw my crashed disc.  Any guidance would be helpful.

Peace,

Kaduflyer

-----Original Message-----
From: BOC/Hawkwind Discussion List
[mailto:BOC-L at LISTSERV.ISPNETINC.NET]On Behalf Of Arjan Hulsebos
Sent: Tuesday, August 26, 2008 4:58 AM
To: BOC-L at LISTSERV.ISPNETINC.NET
Subject: Re: OFF: Drives and backups (was: Re: +++stop
press+++advertising aid item french hassan+++one man isolator+++)


On Mon, 25 Aug 2008 12:23:26 -0400, Paul Mather wrote
> One of the things to remember about hard drives is that though they
> have automatic bad sector reallocation, it is only triggered on a
> write.  So, if you have data sitting on a sector that subsequently
> goes bad, there's nothing the drive can do about it.  That's where
> redundant schemes like RAID come in: it can try and recover the data
>  automatically from other drives in the RAID, or from parity
>  information.  Alas, this is where you can also discover that other
> drives in the RAID, say same models from the same manufacturer or
> same  batch, have also failed in similar fashion, and the multiple
> failures  cause the RAID itself to fail.

This is especially true when you do disk mirroring...

> Because of this cluster failure phenomenon, enterprise level RAID
> controllers will usually have an option for the controller to
> periodically "police" the entire surface of all attached drives,
> making sure the data are readable.
>
> Arjan, you might want to look into  using the ZFS filesystem for
> your  fileservers.  One of its main design features is to try not to
> trust  data coming from various subsystems unless it can verify it.
> Thus, it  employs various levels of checksumming and redundancy.  It
> tries to be  proactive about data integrity, too.  It has a "scrub"
> function that  tries to discover bad sectors, and, in a RAID
> configuration, automatic  resilvering when bad data are discovered.

ZFS is very groovy, more so when you have _lost_ of Gigs to throw into the
game.

Gr,

Arjan H

--------------------------------
Rock in the 70ies:
   substance inhalation, hotel devastation, and amplifier obliteration