Very poor speeds writing to disk Backup Exec 2010 R3

Hi there,

 

I have a D2D2T running daily differentials and a weekly full (on Friday) backup setup here and although working correctly I'm having huge problems getting a decent speed writing to the diskbox.

 

When the backups first start I get 1700mb/min which is great, after ~10mins they drop dramatically to around 100mb/min and when I have all 9 jobs running at the same time I get 60-80mb/min. Writing to tape, however, is much faster often exceeding 1000mb/min and never goes below 800mb/min.

 

As the setup previously worked without problems I presume I have made a mistake somewhere in Backup Exec 2010 R3.

 

I have 2 media sets:

 

One is named 'Daily Differential Backups' and has overwrite protection period of 2days and 'infinite - allow append'

 

The other is 'Weekly Full Backups' overwrite protection: 8days and 'infinite - allow append'

 

Under Policy settings of each of the jobs I have 'overwrite media' set when writing to the diskbox and 'append to media, overwrite if no media is available' for writing to tape.

 

I really don't know where I'm going wrong and was hoping somebody could help,

 

Regards,

 

Alex