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Too many tapes being used for NDMP incrementals

systematic92
Level 5

Hi All,

 
We are finding our jobs are using more tapes than neccessary and I was wondering if anyone knew of how I can resolve this. Here's the setup:
 
- We are using BEXEC 2014
- All our backups are NDMP from NetApp
- We have incrementals configured correctly (level 0, 1, 2, 3 etc.)
- We have all our backups set to Append to media, overwrite if no appendable media is available
- We have 7 HP tape drives
- We use LT05 tape media
- W have no excryption enabled
- We have the compression for every job set to Hardware (if available, otherwise none)
- We have 18 jobs running each night
- The total of our jobs (Mon-Fri) are approximately 5 - 6TB per day
 
I hope all the above helps.
 
Each day our incremental jobs are taking up 13 - 15 LTO5 tapes that are all capable of supporting 3TB of writable space. If we were to be conservative and say that each tape cartridge could only support 1.5TB of writable space, then realistically, we should only be using 4 tapes per night....However, given our environment, the following occurs:
 
As we have 7 drives, 7 jobs start immediately, therefore I am only expecting to remove 7 tapes each day.
 
Am I wrong in thinking this?
 
 
 
 
3 REPLIES 3

Colin_Weaver
Moderator
Moderator
Employee Accredited Certified

if you are appending then Backup Exec will use the remaining space and then use a second tape if that available space is not enough for the job, as such apart from when all the jobs overwrite the tape it is very possible that you might use more tapes than expected.

 

Note You cannot append to the end of a tape and when that tape fills start using the beginning of the same tape, a seconnd tape will be used - and that second tape has to be overwritten as well the second tape cannot be appended to.

systematic92
Level 5

I get that part but each day im pulling 15 tapes out and 7 of them have less than 50gb written to them. They can support up to 1.5TB compressed.

Its as if the job finishes, the tape is sent back to its slot, the next job starts and commences on a new media in the library rather than appending to the tape that just finished job 1....

Colin_Weaver
Moderator
Moderator
Employee Accredited Certified

My answer in this post was kind of an assumption that you daily backup was trying to use two tapes when you expected it to use 1.

Having now seen your other post, please see my answer in the other post for scenarios where a small amounts of data is written to a tape but the tape is not filled and instead other tapes are used.

 

Basically between the two posts you need to look at

Which jobs start as overwrites

Which jobs start as append

Which media sets each jobs use

How many jobs run in parallel