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New Backup System: Does 'Uncompressed' option use Hard Links?

Discussion in 'Data Protection' started by Valetia, Aug 21, 2013.

  1. Valetia

    Valetia Well-Known Member

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    Does the 'Uncompressed' option in the new Backup System use hard links to save space across multiple backups, similar to the way the 'EXPERIMENTAL: Use Hard Links for weekly and monthly backups to reduce disk usage and backup time' option does it in the Legacy Backup System?
     
  2. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello :)

    The difference with the uncompressed option is simply the nature of how the backup files are archived. It does not use compression, so the backup files are placed into an archive in less time. The fundamental nature of how the backup files are generated is not different from the compressed option.

    Thank you.
     
  3. Valetia

    Valetia Well-Known Member

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    Hi Michael, thanks very much for your reply. :) But it still doesn't really address the question of whether the uncompressed backups utilize hard links amongst multiple backups per account in order to save space. :(

    For instance, if one were to retain 5 days' worth of daily backups, then without hard links, they would normally take up 5 times the space of a single backup, assuming little to no changes in the data over the 5 days.

    On the other hand, if they did utilize hard links, they would only take up the space of 1 days' worth of backups, plus any additions that may have been made to the data during the 5 days.

    The 'EXPERIMENTAL: Use Hard Links for weekly and monthly backups to reduce disk usage and backup time' option from the Legacy Backup System achieves just that, and since there isn't such an option listed with the new Backup System, we were wondering if that means it's now "baked in" for Uncompressed Backups.

    If the new Backup System does not utilize hard links to save space, that would be a step backwards in a sense, while being storage-inefficient.

    Hope this makes the question clearer. Any advice would be welcome. :)
     
  4. cPanelMichael

    cPanelMichael Forums Analyst
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    This option is not enabled by default with the new backup system, however it is available as an option that you can manually modify in:

    Code:
    /var/cpanel/backups/config
    The value is called:

    Code:
    LINKDEST
    Thank you.
     
  5. Valetia

    Valetia Well-Known Member

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    Yikes, we just tried running a backup using the new Backup System and found the uncompressed option creates one .tar file per account, rather than the individual files and folders residing within the account (which is what's normally needed in order for hard links to work).

    So would it be correct to say that hard links are not supported with the new Backup System?
     
  6. Valetia

    Valetia Well-Known Member

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    Ah cool, I had no idea hard linking is able to work with the contents of .tar files (if that's what you meant).
     
  7. leat

    leat Member

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    I would assume hard links only works with incremental backup.

    However, I also would like to get an black and White answer whether hard links are used for the monthly retention copy when incremental backup is used.
     
  8. leat

    leat Member

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    root@007 /backup/monthly/incremental/system/files # ls -li /backup/incremental/system/files/_etc_shadow
    24313894 -rw------- 2 root root 1966 Jul 24 21:20 /backup/incremental/system/files/_etc_shadow
    root@007 /backup/monthly/incremental/system/files # ls -li /backup/monthly/incremental/system/files/_etc_shadow
    24313894 -rw------- 2 root root 1966 Jul 24 21:20 /backup/monthly/incremental/system/files/_etc_shadow

    Seems the default is to use hard links. Good.
     
  9. Valetia

    Valetia Well-Known Member

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    Well, that is great news indeed.

    However, if the incremental backup option uses hard links, then why is it limited to only a single daily backup?

    Surely the use of hard links is greatly beneficial to the feature of retaining multiple days' worth of backups.

    Why would this feature only be available via the uncompressed/compressed options, given that they do not utilize hard links? :confused:
     
  10. cPanelMichael

    cPanelMichael Forums Analyst
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  11. leat

    leat Member

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    It's a bit strange to have to request for feature that used to exist. I assume a feature request is also necessarry to restore from retained incremental copies. Good both backup systems are availble however.
     
  12. Valetia

    Valetia Well-Known Member

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    Your comment made me want to laugh and cry at the same time. ;)
     
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