Overview:
Use% in nbdevquery is incorrect when using Media Server Deduplication disk pools at NetBackup 7.0 and 7.1.


Environment:
On a deduplication media server, Use% from nbdevquery is not calculated using crstat so the Use% for nbdevquery is not related to crcontrol. This causes a disconnect between NetBackup and Media Server Deduplication option, so full disk conditions are not going to clean-up as expected.

File system space does not come directly from NetBackup, crstat cli is used to get this. Then, an additional Content Router api is used to get the space free in the containers. On Windows hosts, the api may not consider space in the containers when reporting space available on the Content Router.


Evidence:

nbdevquery -U -listdv -stype PureDisk
 
Disk Pool Name : MSD_20G
Disk Type : PureDisk
Disk Volume Name : PureDiskVolume
Disk Media ID : @aaaab
Total Capacity (GB) : 19.99
Free Space (GB) : 0.22
Use% : 98
Status : UP
Flag : ReadOnWrite
Flag : AdminUp
Flag : InternalUp
Num Read Mounts : 0
Num Write Mounts : 1
Cur Read Streams : 0
Cur Write Streams : 0
 

 
Here is the dsstat output of the containers:
 
crcontrol --dsstat
************ Data Store statistics ************
Data storage Size Used Avail Use%
20.0G 9.1G 10.9G 46%
Number of containers : 73
Average container size : 243464816 bytes (232.19MB)
Space allocated for containers : 17772931634 bytes (16.55GB)
Space used within containers : 9137017614 bytes (8.51GB)
Space available within containers: 8635914020 bytes (8.04GB)
Space needs compaction : 15612588 bytes (14.89MB)
Records marked for compaction : 164
Active records : 76302
Total records : 76466

 

Solution:

Lower the threshold numbers in contentrouter.cfg on the NetBackup MSDP mediasvr.

 

NOTE: for UNIX/Linux based MSDP platforms (other than the Symantec NetBackup 5200/5220 appliance), and for PureDisk storagepools, do not modify the WarningSpaceThreshold, LowSpaceThreshold and VeryLowSpace thresholds to the aforementioned values due to the way non-Windows filesystems may reserve space. Doing so could cause corruption if the amount of used space exceeds the filesystem's internally controlled reserved space. For example, filesystems formatted with ext3/ext4 reserve 5% of blocks by default. This can be changed via 'tune2fs'. Consult the documentation for your operating system before changing the filesystem.

 

On NetBackup MSDP mediaservers the contentrouter.cfg file is located within <dedup_path>\etc\puredisk (or <dedup_path>/etc/puredisk on UNIX/Linux systems)
 

1. Save a copy of the existing contentrouter.cfg file

2. Edit the 'WarningSpaceThreshold, LowSpaceThreshold and VeryLowSpaceThreshold lines to look like:

WarningSpaceThreshold=4
LowSpaceThreshold= 4
VeryLowSpaceThreshold = 3

 

3. (Optionally): set the high water mark (HWM) on the dedup diskpool to 100% via NetBackup administration console or via commandline on the NBU master:

nbdevconfig -changedp -stype PureDisk -dp <diskpool_name> -hwm 100


Formal Resolution:
This issue is currently scheduled to be resolved in NetBackup future version 7.5.
As future versions are released, please visit the following link for download and readme information:

http://www.symantec.com/enterprise/support/downloads.jsp?pid=15143