>My understanding is that the answers to the questions posed below are both YES
>due the transaction
al design of ZFS. However, I'm working with some folks that need more details
or documents describ
ing the design/behavior without having to look through all the source code.
>
>[b]Scenario 1[/b]
>* Create file
>* Open and Write data to file
>* Issue fsync() call for file
>
>[b]Question:[/b] Is it guaranteed that the write to the directory occurs
>prior to the write to th
e file?
It is guaranteed that the view will be consistent (note that you cannot
create a file without opening it, though).
There are, of course, three objects being written: the directory entry,
the file node and the file content.
ZFS guarantees that:
if the directory entry exists, it will point to a valid node
if the node exists, it will point to valid file content
But all of these can be in the same transaction group and show up at once
(or none will show at all).
In total, think of the following transaction happening for file create +
write & sync (sync only alters timing, so is not really relevant):
a) writing the directory entry
b) writing the node (create file w/ size 0)
c) writing the file's content
d) writing the node (update size to reflect written content and
block pointers)
Only a partial order is defined and only b needs to happen before a and c
before d. (b < a, c < d) In theory, you can have a sequence of c, b+d, a.
>
>[b]Scenario 1[/b]
>* Write an extended attribute (such as a file version number) for a file.
>* Open and Write data to file
>* Issue fsync() call for file
>
>[b]Question:[/b] Is it guaranteed that the extended attribute write occurs
>prior to the write to
the file?
No, unless the attribute is fsync'ed also.
>Additionally, is it possible that there are differences in this behavior as
>relates to these scena
rios between Solaris 10 U4 or a SXDE 01/08 implementation (snv_b79)?
Why does the customer want to know?
Casper
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