On Wed, Apr 18, 2012 at 11:52 PM, Tony Asleson <tasleson@...> wrote:
> Unfortunately some inconsistencies have cropped up in the terminology
> used in the library. When people hear the terms: snapshot, clone,
> copy, mirror etc. they can mean different things to different people. I
> would like to clearly define what terms the library should use and
> document their associated meaning.
> I am looking for what the following should be referred to in the library
> (I am missing some as there is a plethora of features out there)?
> 1. Point in time, space efficient read only copy of data
> 2. Point in time, space efficient read/writable copy of data
> 3. Bit-identical copy of data (requires same amount of space as the source)
> 4. Bit-identical copy of data that is continuously updated (sync. or
> async.) This could include locally connected disks (RAID mirroring)
> * LVM calls 2 a snapshot and 3 a clone
> * NetApp calls 1 a snapshot, 2 a clone/FlexClone
> * SMI-S calls 2 a snapshot, 3 a clone, 4 Mirror
> I'm leaning towards (smaller amount of change in library :-)
> 1. SNAPSHOT
> 2. CLONE
> 3. COPY
> 4. MIRROR_SYNC & MIRROR_ASYNC (This could require quite a few options)
> Once we get some consensus, I will rename enumerations/calls in the
> library to make them consistent.
API might need to follow the definition of SNIA (Storage Networking