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SauravKr_'s avatar
SauravKr_
Level 3
11 years ago
Solved

Does NetBackup, restores sparse data as original data.

I backuped a large amount of sparse data, it occupies very little space on the source, but when I restored the data it occupies full space same as the size of sparse data.

7.6
Backup and Recovery
Basics
NetBackup
Restore
Windows Server (2003-2008)
  • Walker_Yang1's avatar
    Walker_Yang1
    11 years ago

    Here is an article for your reference.

    https://www-secure.symantec.com/connect/articles/accelerator-backup-sparse-file

    As it said, sparse file has two size, one is logical size, other is physical size. NetBackup only backups the actual physical non-zero data to server, when restore data, i think, it would occupy the logical size.

    Can you compare the restored data to the original data to see if they are identical?

    Thanks

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  • Nicolai's avatar
    Nicolai
    Moderator
    11 years ago

    Can you elaborate on that.

    What version if Netbackup

    What client OS

    What Netbackup client type (Windows, Oracle, UNIX, Flash-backup etc)

    Consider to do a bppllist -U NAME_OF_POLICY and attach the output as a file to the next post. This will help us understand the issue.

  • SauravKr_'s avatar
    SauravKr_
    Level 3
    11 years ago

    Netbackup 7.6

    Client OS Windows2003

    Netbackup client type Windows

    I am explaining further

    1. I created a iscsi lun. Mapped it on windows machine.

    2. Created sparse data on that lun.

    3. Backed up the lun, on tape library.

    4. While restoring it is considering sparse data as original data and consuming large amount of space.

  • Marianne's avatar
    Marianne
    Level 6
    11 years ago

    Please tell us what exactly this 'sparse' data is? 

    I thought it was a dedupe volume on a W2012 client, but not possible with W2003.

    Even with W2012 dedupe volume, the NBU documentation says that data is rehydrated (full size) when restored.

    Probably the same in this case.

  • SauravKr_'s avatar
    SauravKr_
    Level 3
    11 years ago

    Sparse data is created using "fsutil.exe", inbuilt tool of windows.

  • Walker_Yang1's avatar
    Walker_Yang1
    Level 5
    11 years ago

    Here is an article for your reference.

    https://www-secure.symantec.com/connect/articles/accelerator-backup-sparse-file

    As it said, sparse file has two size, one is logical size, other is physical size. NetBackup only backups the actual physical non-zero data to server, when restore data, i think, it would occupy the logical size.

    Can you compare the restored data to the original data to see if they are identical?

    Thanks

  • SauravKr_'s avatar
    SauravKr_
    Level 3
    11 years ago

    I missed your question

    what exactly this 'sparse' data is? As already suggested by Walker, Basically sparse data occupies more disk space then it's actual size. So, sparse data  basically contains zero filled file or empty file occuping a large on disk space. So, they occupy space more efficiently. So, when we compress a sparse file, it's size become too small.

     

    Can you compare the restored data to the original data to see if they are identical? >> yes, they are identical, they are of the same size also.

     

     

  • SauravKr_'s avatar
    SauravKr_
    Level 3
    11 years ago

    Yes may be, I think it is just looking to iscsi as a file of a particular size, and not looking to the data inside it.