NetBackup With Vault - How To Make Vault Tape Usage More Efficient

[yarbrough2]

Hi all,

I am using NetBackup 6.5.1 with the vault option. We run backups to a Virtual tape library and then use vault to copy the images from the VTL to tape. We recently started an incremental routine for several of our large backups. Before the incremental routine was implemented our vault used approximately 12 LTO3 tapes. After the incremental routine was instituted I expected the number of tapes used to decrease, but I have not seen any decrease at all. We are still using about 12 tapes every day for our vault. I have done research to try and figure out why this is, but I have come up empty handed. I have done two things in an attempt to change our vault up, they are as follows:

1. Reducing the number of streams for the source backup job (hoping that reducing the number of streams would force the data from the image to write to less tapes).
2. Using the "Duplicate smaller images first" option on the Duplication tab of the vault profile.

Neither of these has helped with my issue. Following is an example of our vault eject list, notice the tape usage. These are LTO3 tapes, 400GB of space should be available:
=======================================================================

Robot: TLD(1) Vault: V1 Profile: V1-Dup
3584 Tape Library: Picking List for Robot

MEDIA SLOTID EXPIRATION IMAGES MBYTES CATEGORY EJECTED
0375L2 708 05/19/2009 2 74935 New CTLG YES
2108L3 243 06/15/2009 3 4219 NBU YES
2109L3 276 06/16/2009 31 112337 NBU YES
2110L3 388 06/15/2009 42 304486 NBU YES
2111L3 758 06/15/2009 17 182371 NBU YES
2112L3 759 06/16/2009 82 91839 NBU YES
2113L3 760 06/15/2009 80 188129 NBU YES
2114L3 761 06/15/2009 58 146456 NBU YES
2115L3 762 06/15/2009 7 21916 NBU YES
2116L3 763 06/16/2009 141 459743 NBU YES
2117L3 764 06/16/2009 153 425703 NBU YES
2118L3 765 06/16/2009 222 576160 NBU YES
2119L3 766 06/15/2009 15 502 NBU YES

TOTALS

Number of Media: 13
MBytes for all media: 2589117
Image count on all media: 853

Number of images for this session: 853
MBytes for this session: 2589117

=======================================================================
The smallest amount of data on one tape is 502MB (2119L3). No tape is fully utilized; all of these tapes had expired and were in the scratch pool before being assigned to the vault for use. I will be glad to provide any information regarding the setup of our backup policy's and vault policies if necessary. Thanks in advance for your help.

John

[netbackup_rooki]

Question:

are you writing your vaulted images to single or mulple volume pools?
Do they have different retention?

[yarbrough2]

Only one volume pool is used with a common retention period.  The retention period and volume pool are setup in the vault profile on the duplication tab.  Unless I'm missing somethig I'm not sure how there could be different volume pools and retentions for the same vault.  Thanks for the response.

[T_N]

Retention period: you can change it in Vault Management properties

[netbackup_rooki]

how many write drives are being used?

[yarbrough2]

We have been playing with that over the past few days.  Currently there are 6 drives available for the vault, we had 8 previously.  Reducing the number of write drives by two has not reduced the number of tapes used for the vault.  I made a change just last night for today's vault as follows:

Number of read drives = 6 (equates to write drives)
Duplicate smaller images first = unchecked (will duplicate large images first, default action for NBU Vault)

At this time we are still vaulting today's vault session, but NBU has only allocated 7 tapes to the current vault session.  I won't be sure the above configuration has helped until the vault completes.  I'll report back once this vault session is complete.

John

[yarbrough2]

Our vault only used 7 tapes today, and they consistently had over 500GB of data:

MEDIA     MBYTES          CATEGORY

1292L3   917730            NBU
1805L3   627423            NBU
1834L3   595673            NBU
1861L3   550350            NBU
1871L3   596414            NBU 
1923L3   12482              NBU
1969L3   80398              New CTLG 
2103L3   593506            NBU     

Hopefully this will be a new trend with the settings we have adjusted.

John

[alazanowski]

I think its based on the date isnt it? That you'd have to enable the switch to allow multiple backup dates to be allowed on a single media for expiration purposes. Maybe i'm wrong, but as far as i remember thats what it came down to. However, its showing all my vault tapes as Suspended Full when its done, so my assumption also is that it utilized the maximum amount of room on the tape. I have TBs upon TBs of data, so maybe i don't notice it as much.

[Dion]

If you are using version 6.5 or higher, go to the properties of your "OFFSITE" pool and change the "Maximum number of partially full media".  Reduce the number until you have a good combination between number of full images and the time taken to do the duplication.

[netbackup_rooki]

i think this is because of the # of write drives that being used.

From my understanding..you are using total of 12 drives 6 for each read and write.

if you have 12 drives available when you start vault it will duplicate to 6 different medias and if there isn't enough data it won't fill up the tape.

try using 2 write drives.. it will increase the time it takes to duplicate all of your images but will reduce media usasge..

my $.02

 

[yarbrough2 · Accepted solution]

It looks like setting the number of read drives to a lower number did the trick.  We have consistently had vaults with fewer tapes, and the tapes are used to capacity.  Thanks for everyone's comments.

John

[netbackup_rooki]

i am happy to know you got things figured out.:)

[read]

Where do you set read drives to a lower number on NBU 5.1? 

[yarbrough2]

I'm sorry I have no practical experience with NBU 5.1.