Patrick Bachmann wrote:
Jonathan,
On Tue, Mar 04, 2008 at 12:37:33AM -0800, Jonathan Loran wrote:
I'm 'not sure I follow how this would work.
The keyword here is thin provisioning. The sparse zvol only uses
as much space as the actual data needs. So, if you use a sparse
zvol, you may mirror to a smaller "disk", iff you use as much
space as is physically available to the sparse zvol.
I do have tons of space on
the old array. It's only 15% utilized, hence my original comment. How
does my data get into the /test/old zvol (zpool foo)? What would I end
up with.
There's no zvol on foo. After detaching /test/old, you may
reconfigure your old array. At that point, foo is on a zvol on
the pool bar.
In what way to get the data over depends on how your
reconfiguration of the old array impacts the pool and vdev size.
If it gets smaller, you cannot attach it to the pool where your
data currently resides and have to go the send|receive route...
Putting the zpool on a zvol permanently might not be something
you want as this creates some overhead, I can't quantisize, and
you mentioned some performance issues you're already
experiencing.
Well, there's the rub. I will be reconfiguring the old array identical
to the new one. It will be smaller. It's always something, isn't it.
I have to say though, this is very slick and I can see this sparse zvol
trick will be handy in the future. Thanks!
Jon
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