Re: RMAN restore into nearly full file system
Date: Mon, 23 Aug 2010 23:10:38 +0100
Were any of the data files on the file system 'sparse'?
Sparse files occur when disk blocks are empty, and rather than allocating a block on disk, the inode makes a note that the block is empty.
In the past no Oracle database files should be sparse, although locally managed temporary tablespaces are now created as sparse files I believe. However these will not normally be backed up by RMAN and shouldn't be a problem.
However I believe that the AIX backup and restore utilities will create sparse files if they have ever been used to restore or move the database files.
On Mon, Aug 23, 2010 at 9:49 PM, Charlotte Hammond < charlottejanehammond_at_yahoo.com> wrote:
> Hi All,
> Recently, when I ran an RMAN restore I got a "no space left on device"
> error and
> RMAN aborted. Why did the restored data files no longer fit onto the disk
> which they were originally backed up?
> (No files had been added to the file system since the backup was taken).
> ls showed the same number of bytes before and after the restore. I presume
> problem was with "hidden" space usage such as inode blocks or file indirect
> blocks. There was only about 20Mb free on the 80Gb file system, yet 20Mb
> seems quite a lot of degredation in the efficiency of file system metadata
> (there were only 5 data files to track). How can I explain the loss of 20Mb
> between backing up and restoring the files? (The file system is JFS2, block
> was 4k, OS is AIX, Oracle 9i (don't ask!))
> I want to use this as further evidence to try to deter a manager from
> overfilling file systems but I'd really like to be able to explain it
> before doing so (he'll be asking questions!).
> Many thanks!