Plans for 1.8+ (2.0?)
wbh at conducive.org
Thu Feb 1 10:47:41 PST 2007
Thomas E. Spanjaard wrote:
Stilyan Tsenov wrote:
I can't uderstand whether snapshots are filesystems or files ?...or
just both possible ?
A snapshot of a filesystem needs support from the filesystem to be
snapshottable, e.g. temporary suspension of all activities on that
filesystem while the snapshot-taking is in-progress.
. .. except for Plan 9, where the 'snapshot' was basically a byproduct of the way
updates were done - i.e. change (and date) only what HAD changed, preserve all
else - even if no longer 'valid'.
By selecting a date/time, the 'collection' of data current at that time could be
had - ergo instant de fact 'snapshot', and to very fine granularity.
An RDBMS where all records are timestamped and never 'vaccumed' can do much the
same - a device we used for years to 'what if' telco service-mix pricing:
- current, historical, or anticipated telecoms traffic
could be 'billed at'
- current, historical, or anticipated rates.
Made comparison much easier w/r adjusting for this and that..
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