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Incremental backups and hardlinks question

Discussion in 'Data Protection' started by postcd, Aug 28, 2017.

  1. postcd

    postcd Well-Known Member

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    Hello, i read Backup Configuration - Documentation - cPanel Documentation

    I see that when i compare one identic file from two daily backups directories they use same inode:
    stat faq.php ../../../../../2017-08-24/accounts/cpanelname/homedir/www/faq.php
    File: `faq.php'
    Size: 1843 Blocks: 8 IO Block: 4096 regular file
    Device: 9007h/36871d Inode: 59901396 Links: 8
    Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
    Access: 2017-08-28 08:00:01.338758490 +0000
    Modify: 2012-06-06 08:06:50.000000000 +0000
    Change: 2017-08-28 02:42:48.745287488 +0000
    File: `../../../../../2017-08-24/accounts/cpanelname/homedir/www/faq.php'
    Size: 1843 Blocks: 8 IO Block: 4096 regular file
    Device: 9007h/36871d Inode: 59901396 Links: 8
    Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
    Access: 2017-08-28 08:00:01.338758490 +0000
    Modify: 2012-06-06 08:06:50.000000000 +0000
    Change: 2017-08-28 02:42:48.745287488 +0000

    So when i backup either one using "rsync -av" or "tar -czf", i will have working file thanks to hardlink?

    But what if the destination file (not hardlink) gets deleted, then all rest daily backup directories will not be able to resolve this file as hardlink will point to no file?

    So it means WHM admins should not manually delete any directories in /backup to prevent missing files shared among archives?

    When i rsync to other server, i will need to do 1:1 of a /backup folder, else if i miss some daily backups, it can result that some files will be inaccessible because hardlinks will point to a missing file?
     
    #1 postcd, Aug 28, 2017
    Last edited: Aug 28, 2017
  2. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    The remote incremental backup process (with rsync) is designed to check if the files associated with the account backup on the cPanel server also exist on the remote backup destination. If the files do not exist on the remote backup destination (or if the files have changed), then it copies the actual files. Otherwise, it makes use of hard links when the files already exist on the remote backup destination. The following document is available if you'd like to read more about how account backup information is stored:

    Metadata for Backups - Version 66 Documentation - cPanel Documentation

    Thank you.
     
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