zfs scrub enable by default

[Bob Friesenhahn]

On Tue, 4 Aug 2020, Karl Denninger wrote:

> Let me give you two allegedly "degenerate" cases that are actually not 
> degenerate at all.
>
> 1. A laptop or workstation.  It is backed up.  It uses ZFS because it's 
> faster, and I can establish a filesystem for some project very easily and 
> quickly, it's segregated, I can work on it and destroy it trivially when 
> done.  I can set quotas on that, etc.  If I want to move its mountpoint, I 
> can trivially do so. And so on.  Note that here there is no redundancy at 
> all; no raidZx, no mirroring, etc.  I'm merely using it for convenience.

Did you remember to set copies=2 or copies=3 for zfs filesystems where 
you hope not to experience data loss?  It needs to be set as soon as 
possible since it only applies to new files.  This is a way to get 
more media redundancy, although the whole drive may fail.

Zfs scrub is not going to protect your precious data from loss given 
just one drive unless you increase the copies setting.  Zfs itself 
already uses redundant copies for its own data structures.

Bob
-- 
Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
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