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Question

LTO9 Tapes keep data less than the native capacity for Selective copy but near the compressed capacity for primary copy

A
Byte
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Dear Vaulters,

I have a question.

 

I’ve configured the backup for a vm group to be on our new LTO9 tape library and configured the selective monthly backup on the same library for long retention.

for the tapes of the primary copy i see that each tapes keep about 37 TB of data whereas each tape for selective copy keep about 16 TB of data.

 

Our expectation is to keep the more data on the tapes assigned to selective copy as the same data are kept on the same library.

 

Please let me know if this is normal behavior.

 

BR 

2 replies

P
Vaulter
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  • PradeepVaulter
  • Vaulter
  • 265 replies
  • April 15, 2025

Hi ​@Ahmed Elbably ,

Selective copies typically pick only the latest full backup for the month and depends on the copy policy.

If your monthly full backup size is smaller (e.g., deduped or fewer VMs), naturally it uses less tape space.
and also it depends on the configuration.

Primary copy would be running both full and incremental depending on the schedules associated.
Request to review the configuration set between primary and aux copy policy.

A
1 person likes this
  • A
    Ahmed Elbably
A
Byte
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Pradeep wrote:

Hi ​@Ahmed Elbably ,

Selective copies typically pick only the latest full backup for the month and depends on the copy policy.

If your monthly full backup size is smaller (e.g., deduped or fewer VMs), naturally it uses less tape space.
and also it depends on the configuration.

Primary copy would be running both full and incremental depending on the schedules associated.
Request to review the configuration set between primary and aux copy policy.

Hi ​@Pradeep 

Appreciate you reply.

 

The monthly full backup is about 120TB (not deduped), I expect them to consume the same number of the tapes for selective copy as the primary copy, these data consumed about 4 LTO9 tapes for primary copy (around 30 TB for each tape) and I guess it’s going to consume more than 6 on selective copy as many tapes are full with only 16 TB of data.

 

BR

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