| Hotbackup [message #239599] |
Tue, 22 May 2007 13:23  |
rsreddy28
Messages: 295
Registered: May 2007
|
Senior Member |
|
|
Hello All,
I was asked in an interview like
" The Tablespace USERS is being kept in hot backup mode and while copying the datafile to the new location, the developers are doing heavy transactions say almost upto 100 Mb and committed within those few minutes of copying and after copying the datafile to another disk, the tablespace has been out of backup."
Now the question is, will the committed transactions of 100 Mb be in the copied new location or Not.What will happen to those transactions.
Kindly let me know.
Hope the question is clear.
bYe,
Raj
|
|
|
|
|
|
|
|
| Re: Hotbackup [message #239609 is a reply to message #239606] |
Tue, 22 May 2007 13:55  |
rsreddy28
Messages: 295
Registered: May 2007
|
Senior Member |
|
|
Hi Michael,
Thanks for your reply , but this question was asked in an interview , so can you do me a favor by reading my question and answer me that. I;m very much confused what would be the best answer for that.
|
|
|
|
|
|
| Re: Hotbackup [message #239612 is a reply to message #239599] |
Tue, 22 May 2007 14:27 |
saibal
Messages: 111
Registered: March 2007
Location: India
|
Senior Member |
|
|
|
See, the moment you put the USERS tablespace in backup mode, a checkpoint occurs only for that tablespace and the SCN for that tablespace is locked. Now when you copy the underlying datafile to a new location, that datafile is not ever going to be a consistent backup, because, with the database open, any copy of the datafile can never be guaranteed to be consistent. In fact, more than likely it will be a fuzzy copy, requiring recovery. It absolutely doesn't matter how much or how little work is going on during the period the file was being copied--the file WILL REQUIRE RECOVERY UPON RESTORATION AND THAT IS IT. Now the recovery will happen from the point the SCN was locked--the whole purpose of locking the SCN is to know the earliest point from which to begin recovery. All the heavy activity that you were talking about will flow from the redo logs into the archived logs, and thus you have all the work done and waiting in the archived logs.When you take your tablespace out of backup mode, there will be another checkpoint as it will try to catch up with all the other tablespaces in the database.
|
|
|
|
) 1 Vote
] 
Blog
Search
Help
Members
Register
Login
Home
