[linux-lvm] Snapshots and disk re-use

Jonathan Tripathy jonnyt at abpni.co.uk
Wed Feb 23 18:19:41 UTC 2011

On 23/02/11 18:05, Stuart D. Gathman wrote:
> On Wed, 23 Feb 2011, Stuart D. Gathman wrote:
>> So you're not worried about the security implication of leftovers in free
>> space, and just want a base image to clone for new customers?
>> The logical thing to do is to keep the origin volume untouched (except
>> for upgrading now and then), and take a snapshot for each customer.
>> Each snapshot would then be a new clone of the origin.  Unfortunately,
>> large numbers of snapshots are inefficient for writes to new data,
>> so you'd likely have to "dd" to an independent LV instead.  (This is being
>> worked on, and there are 3rd party products like Zumastor that fix it now.)
> Actually, if you never (or rarely) write to the origin, lots of snapshots
> should be fine.

> But every write to the origin will first copy the
> original origin data to every snapshot.
Why would origin data be copied over to the snapshot after the snapshot 
has been created? Surely the point of a snapshot is to have "frozen" data?

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