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Very Slow Backup Times / Media Mount Latency

Created: 12 Mar 2012 | 4 comments

Symantec Backup Exec 10d for Windows Servers (Small Business Server Suite) Version 10.1 Rev 5629

Windows Server 2003 SBS SP2 (32-bit)

Intel Xeon 3.0GHz

4.00GB RAM

I've been suffering with this issue for quite awhile now and I suppose it's time to address it.  A full backup of ours is about 600-700GB in size.  Our incremental backups go to a tape drive (and can take around 56 hours), but our full backups go to an eSATA external 1TB hard drive.  I start from a quick formatted external drive every time.  A full backup has been known to take 100+ hours.  I think that's completely ridiculous.  I attribute some of the latency to our slow server, however I've come to the realization that this can't be the only cause.  Since I cannot do backups over a weekend, it has begun to affect normal business.

Recently, I looked at the amount backed up at certain times throughout the backup and noticed something a bit strange.  It seems the backup time "exponentially" increases as there are more bkf files created.  For instance, in the first 4 hours, it backed up 110GB.  The last 9 hours backed up 37GB.  I looked at the log and noticed that I see a media mount for each of the files created in the backup.  Currently, it is set to the 1GB file size default.  Probably not a problem, but I then notice that the time between the "media mount request" and the "media information from media mount" time is ever increasing.

For Example:

The First Mount (5 seconds)

Drive and media mount requested: 3/9/2012 2:55:12 PM

Drive and media information from media mount: 3/9/2012 2:55:17 PM

The Last Mount (13 minutes 4 seconds!)

Drive and media mount requested: 3/12/2012 8:58:42 AM

Drive and media information from media mount: 3/12/2012 9:11:46 AM

You can imagine how much time is wasted if you have hundreds of bkf files.  During this mount time, Backup Exec displays "loading media".

My questions:

1. What exactly is happening during this time?  Why is it taking an ever increasing time?  Why can it take 13 minutes or more?  What can I do to speed this up?

2. I know I could increase the "Maximum size for Backup-to-Disk files", which would decrease the number of these media mounts significantly.  Although I might be better resolving the root problem based on answers to question #1.  Are there any general guidelines or pros/cons to particular sizes to bump it to?  I was thinking something like 10-25GB.  The bigger, the better depending on the cons list.



Comments 4 CommentsJump to latest comment

Lesta G's picture

For backup exec 2010 the default is 4GB , if that is of any help.

I think the issue in in increasing the backup file size is in terms of what you are able to recover if for some reason the backup file is corrupted.


for best practices


tray a different cable in case the cable is an issue

see if there are any updates to the esata controller on the server

If this response answers your query, please mark it as a solution

pkh's picture

If you set the max size of your .bkf file to a big amount and check the allocate max size, then it will take a long time to allocate the .bkf, especially if your disk is fragmented.  This is not a BE problem, but more of a OS problem.

melview1's picture

So I figured I'd give it a shot and I bumped the bkf file size up to 4GB.  If tha'ts the default of the latest Backup Exec version, then I think that should be ok. 

I ran a 700 GB full backup and the time to complete went from 100 hours to 26 hours.  I can finally complete a full backup over the weekend.  This still, however, doesn't answer question #1.

Lesta G's picture

I would manyally copy files from the server to the external disk and work out what the maximum transfer rate is.

Have your run a chkdsk on the external disks? (could be issues on the disks)


try a different cable in case the cable is an issue

see if there are any updates to the esata controller on the server

Oh and in terms of maximum file size of BKF file. All depends on how much data you are willing to loose if the bkf ends up corrupt.


if all your files are 6GB big then you perhaps could risk going higher?

if you have 500 files in a 4GB bkf file then you run the risk that you will not be able to recover those files

If this response answers your query, please mark it as a solution