Ian Collins wrote:
On 04/17/10 12:56 PM, Edward Ned Harvey wrote:
From: Erik Trimble [mailto:erik.trim...@oracle.com]
Sent: Friday, April 16, 2010 7:35 PM
Doesn't that defeat the purpose of a snapshot?
Eric hits
the
nail right on the head: you *don't* want to support such a "feature",
as it breaks the fundamental assumption about what a snapshot is (and
represents).
Ok, point taken, but what you've stated is just an opinion. It's not a
fundamental necessity, or a mathematical necessity, or impossible to
think
otherwise, that a snapshot is 100% and always will be immutable.
But is a fundamental of zfs:
snapshot
A read-only version of a file system or volume at a
given point in time. It is specified as filesys...@name
or vol...@name.
As Ian said. Also, take a look at the old conversation about writeable
snapshots - sure, it's my /opinion/ that snapshots should be read-only,
but it's also a fundamental design decision made when ZFS was started.
There's actually non-trivial assumptions in the code about the
immutability of a snapshot, and I'd not want to go down that path of
changing a fundamental assumption of the whole system.
The problem with mutable snapshots is that you've moved over into the
realm of a "versioning" filesystem, and that's a whole 'nother rats nest
of complicated issues.
--
Erik Trimble
Java System Support
Mailstop: usca22-123
Phone: x17195
Santa Clara, CA
Timezone: US/Pacific (GMT-0800)
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