A queue can form for a storage unit if the storage unit is unavailable.

Storage units are local.Both media servers are AIX6.storage unit group configured with 2 storage units as failover

The only exception to the storage unit selection criteria order is in the case of a client that is also a media server with locally connected storage units. The locally available storage units take precedence over the defined sequence of storage units in the group.

http://www.symantec.com/business/support/index?pag...

I am assuming it would be same for Unix servers also.

so the jobs that are using the 2nd storage unit are local to the jobs?

We only have storage unit groups.This group has 2 storage units configured as failover.one on Server A, The other on Server B ,but the failover takes place as soon as the limit of the first storage unit is reached,instead of queueing

could you provide the output of below commands

 bpstulist -label <1st stuname> -U

bpstulist -label <2nd stuname> -U

bpstulist -group  <STu Group>

bpstulist -group I6866610_ACS_LANA_LTO4 -U
I6866610_ACS_LANA_LTO4 3 I6866610_ACS_LANA_LTO4_1200 I6880010_ACS_LANA_LTO4_1200
 

bpstulist -label I6866610_ACS_LANA_LTO4_1200 -U

Label:                I6866610_ACS_LANA_LTO4_1200
Storage Unit Type:    Media Manager
Host Connection:      i6866610bu.sbb.ch
Number of Drives:     4
On Demand Only:       yes
Max MPX/drive:        24
Density:              hcart - 1/2 Inch Cartridge
Robot Type/Number:    ACS / 1
Max Fragment Size:    15000 MB

bpstulist -label I6880010_ACS_LANA_LTO4_1200 -U

Label:                I6880010_ACS_LANA_LTO4_1200
Storage Unit Type:    Media Manager
Host Connection:      i6880010bu.sbb.ch
Number of Drives:     4
On Demand Only:       yes
Max MPX/drive:        24
Density:              hcart - 1/2 Inch Cartridge
Robot Type/Number:    ACS / 1
Max Fragment Size:    15000 MB

nbujobber,

i am not seeing anything odd on above config,

1)how many clients you are trying for this test?

you have 2 media server 

i6866610bu.sbb.ch

i6880010bu.sbb.ch

so when Failover is taking place for I6866610_ACS_LANA_LTO4_1200 to I6880010_ACS_LANA_LTO4_1200, what is the client name that is using that 2nd stoarge unit?

does it the 2nd Media server as a client? or some other Client?

the reason I am asking this is , I have read the below statement in tech note

The only exception to the storage unit selection criteria order is in the case of a client that is also a media server with locally connected storage units. The locally available storage units take precedence over the defined sequence of storage units in the group.

http://www.symantec.com/business/support/index?pag...

if that is the 2 nd media server as a client could you try the backup with other clients by excluding the 2nd media server for backups?

No clients are media servers,we tried adding the second storage unit again last night,and the same thing happend.at some stage the backups start running on the second storage unit as well.as of this point on both are active

its Really Odd behiaver, what is your Netbackup Versions and OS,

Probably you would need to get the  Symantec support to check if they have any Known bugs with this.

OS .AIX 6.1 Netback 7.1

problem still exists