On Apr 25, 2010, at 5:45 AM, Edward Ned Harvey wrote:
>> From: Richard Elling [mailto:richard.ell...@gmail.com]
>> Sent: Saturday, April 24, 2010 7:42 PM
>>
>> Next,
>> mv /a/e /a/E
>> ls -l a/e/.snapshot/snaptime
>>
>> ENOENT?
>>
>> ls -l a/E/.snapshot/snapname/d.txt
>>
>> this should be ENOENT because d.txt did not exist in a/E at snaptime.
>
> Incorrect.
>
> E did exist. Inode 12345 existed, but it had a different name at the time
> of snapshot. Therefore,
> a/e/.snapshot/snapname/c/d.txt is the file at the time of snapshot.
> But these are also the same thing:
> a/E/.snapshot/snapname/c/d.txt
> a/E/c/.snapshot/snapname/d.txt
OK, I'll believe you.
How about this?
mv a/E/c a/c
mv a/E a/c
mv a/c a/E
now a/E/.snapshot/snapname/c/d.txt is ENOENT, correct?
> It would be very annoying if you could have a directory named "foo" which
> contains all the snapshots for its own history, and then "mv foo bar" and
> suddenly the snapshots all disappear. This is not the behavior.
>
> The behavior is: If you "mv foo bar" then the snapshots which were
> previously accessible under foo are now accessible under bar. However, if
> you look in the snapshot of foo's parent, then you will see "foo" and not
> "bar". Just the way it would have looked, at the time of the snapshot.
>
The only way I know to describe this is that the path is lost.
In other words, you cannot say ../.snapshot/snapname/self is the same as
self/.snapshot/snapname, thus the relationship previously described as:
Snapshots are taken. You can either file.txt via any of the following:
/root/.snapshot/branch/leaf/file.txt
/root/branch/.snapshot/leaf/file.txt
/root/branch/leaf/.snapshot/file.txt
is not guaranteed to be correct.
-- richard
ZFS storage and performance consulting at http://www.RichardElling.com
ZFS training on deduplication, NexentaStor, and NAS performance
Las Vegas, April 29-30, 2010 http://nexenta-vegas.eventbrite.com
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