Weekly full backups are staged to an EMC Data Domain basic disk staging storage unit. Staging to a 6 drive LTO4 robot is triggered by a schedule at 3PM which takes more than the sheduled window to complete. Tape-only policies that are sceduled at 11PM fail with status 196 because all drives are occupied by the staging. How can I ensure that the staging has less priority than regular backup policies? Is this recommended? I want to avoid tweeking with policy priorities which are all at 0. The staging schedule has a priority of 90000 which makes no sense to me.

This might take it off topic but why only weekends for FULLs? Can't the normal FULLs be spread during week nights and larger FULLs done during weekends?We do have FULLs spread out during the week and starting 1700hrs. Larger FULLs (file shares) are usually done once a month with weekly CUMMs. We are able to do this probably because it is a small environment: about 1000 VMs, about 30 NDMP backup, 20 file share policies (with lots of data/change) and about 200 - 300 client based backups. The setup is of storage is similar though: 2 DDs (2 copies) and then duplication to LOT7 tapes for data which is not good for deduplication.Edit: Forgot to tell that the media servers are connected to the DDs and tape library via SAN FC connections

I will look into SIZE_DATA_BUFFERS as all are default. But first I want to attempt to pinpoint the problem as all this hardware has been running fine for years.... although we have been increasing the load steadily in the last year and perhaps we were'nt paying attention well enough. Getting the big picture isn't always obvious.

Using a LTO 3 tape in a LTO4 tape drive will cause the LTO4 drive to behave as a LTO3 drive - including tape write speed. I can't see any other option than visual inspection of returning tapes to remove LTO3 tapes. The number of GB a tape contain, can be a indication as LTO3 contain 400GB vs LTO4 800GB uncompressed.

Use the time between a "begin read" and "end read" message on a duplication job to calculate the transfer speed. If using a 50GB fragment size : 6:30 min = 136 MB/sec10:00 min= 83MB/sec20:00 min= 40MB/sec40:00 min= 20MB/sec Take more samples to ensure you see the right picture.

Why start staging only at 3pm? Best to schedule staging fairly often. Like every 2-3 hours.

Disk staging to tape causes status 196 on regular policies

Marianne
Level 6
8 years ago
Why start staging only at 3pm?
Best to schedule staging fairly often. Like every 2-3 hours.
- JeanB
  Level 4
  8 years ago
  I was thinking of setting it every hour with a 24 hour window. We started having these problems when we transfered more than 3TB of backups to this staging disk unit. Duplication takes ages. How can the size of the duplication be evaluated? Also, has we are not using SLPs, I understand that high and lower water marks are not used. They are set at 90% and 75%, the unit is currently full to 72%. My understanding is that all backups done using this storage unit since the last staging will be duplicated, disregarding the water marks.
  - Nicolai
    Moderator
    8 years ago
    You can speed up tape transfer by setting SIZE_DATA_BUFFERS = 262144 and NUMBER_DATA_BUFFERS to 256. This tewak can increase performance up to 50% compared to default values.
    
    Stage during day time and backup during night time. Mixing work load will effect performance.
Marianne
Level 6
8 years ago
Let's get back to basics -

You have backup requirement for xxx amount of data.
You have duplication requirement for xx amount of data.
You have x hours in which to complete these tasks.
You have resources capable of reading data at ?/sec. (this includes read speed from client disk and disk STU)
You have resources capable of writing data at ?/sec (including network transfer rate)

If you don't know what each of these points amount to, then you have you homework cut out.

How long do the backups to disk take to complete? What transfer rates are your seeing?
How long do duplications take to complete? At what transfer rate?
If you are not seeing all 6 tape drives writing duplications to 6 drives at more than 100MB/sec, then you need to look at the entire data path.
If you are using a single master/master server, you need to verify that this server has sufficient resources for each of the processes involving backups and duplications.

About disk staging - HWM does not play a role in duplication scheduling - this is the task of the schedule in the DSSU schedule that you configure.
HWM is what starts disk cleanup.

Herewith some reading matter about disk staging:

DOCUMENTATION: Description of NetBackup Disk Staging Relocation Behavior
http://www.veritas.com/docs/000030287

Disk Staging Storage Unit (DSSU) cleanup behavior
http://www.veritas.com/docs/000036495
- Nicolai
  Moderator
  8 years ago
  Both X2 and Marianne posts are very valid and basically is the essence in ensuring backup windows.
  
  You really need to figure out how bad or good duplication speed are. Please look at the NUMBER_DATA_BUFFERS/SIZE_DATA_BUFFERS tuning I suggested before. It may be simple as that in resolving the replication backlog you have.
  
  How to configure the buffer settings is documented in "Netbackup backup planning and performance tuning guide"
  - JeanB
    Level 4
    8 years ago
    I need to identify the problem that causes one of the media servers to take more than 43 hours to duplicate 18TB (still not completed as I'm writing). The other media server (identical hardware) took 26 hours for 12 TB, time which was mostly spent on one 4TB job.

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Disk staging to tape causes status 196 on regular policies

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