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CIFS backup file size

Created: 21 Feb 2013 • Updated: 18 Mar 2013 | 2 comments
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We have Backup Exec 2012 running backups to CIFS on a Quantum DXi6700.  I've been looking into setting up the maximum file on the storage properties in Backup Exec because it was initially set to 4GB by the tech who configured it, which would make the backup job go to 'loading media' for a duration of 60 seconds after writing each 4GB file.  This adds up in a large backup job.  As a test I changed the maximum file size to 12GB and a test job was much faster.

My questions are, what is the impact of increasing the maximum file size settings, is there an optimal/recommended setting?  The only documentation that I could find states that Backup Exec will by default set the maximum file size to 50GB or the capacity of the disk.


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CraigV's picture


If you increase the size of your B2D, it means bigger file sizes allocated to the backups, and if duplicating to tape, better performance as less B2Ds are streamed.

From a backup, and specifically restore perspective, the larger the files, the more data you fit into them, and should you have less B2D files with more data and 1 fails, you run a greater risk of losing considerably more data.

Ie. you backup 50GB with 5GB file sizes = 10 files. losing 1 of the 10 files = 10% data loss...backing up the same data with 10GB file sizes = 5 files. Losing 1 of the 5 = 20% data loss...

By default, the B2D file size is 4GB, and I have seen guys increase the size. See what is fit for your environment...


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pkh's picture

4GB is the default max size for .bkf in previous versions of BE.  This has been bumped up to 50GB.  I would leave it 50GB.  There is no recommended max size.  It all depends on the size of your backups and the size of your disk.  Suppose your backup is 200GB.  If you have a max size of 4GB, then you would end up with a lot of small files and your disk will be fragmented.  As you have also found out, allocating files does cause overheads.  If you use 50GB then a more reasonable number of .bkf files would be used.