>Data is copied from the snapshot. Time could become important if the
>load on your filer during backup interferes with your production
>environment...
>Or the change rate on your volume when space is running low.

Not to nit-pick, but all data technically comes from the active volume for 
backups (at least CIFS & NFS, I have no experience w/ FC & iSCSI).  WAFL 
doesn't implement copy-on-write snapshots.  As a result data "within" a 
snapshot is located on the same volume as the active data.

A NetApp snap really is just a window to a point-in-time and not a 
separate file system.  The only difference between a snap and the active 
file system with NetApp is that the active file system always points to 
the most recently modified block of a file.  A snap always points to the 
block as it existed when the snap was taken.

New/Modified data doesn't overwrite the old data, it's written to spare, 
contiguous free blocks to improve write performance.  The snap points at 
the old blocks that are still in place.

So, whether your pulling data out of a snap or from the active file 
system, it's all hitting the same volume and therefore the same disks. 
This can become problematic for backups when you have multiple flexvols on 
a single aggregate that you need to backup at the same time.

HTH,
Jeff

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