Open file handling for Avamar backup of UNIX, Linux, and Windows clients

A user would like to know how Avamar handles the backup of open files.

On Windows:

Windows file handling provides exclusive access and nonexclusive access to open files.

For Avamar to back up files which are open by some other application, Avamar uses Microsoft VSS on Windows XP and later. VSS creates a snapshot of the file system which remains static. Avamar backs up the static snapshot and does not contend with other applications that have an exclusive lock on the original file.

 
UNIX and Linux:

UNIX and Linux, unlike Windows provide nonexclusive access to files. Since an application may have the file open nonexclusively, Avamar backs up such files whilst they are open by the application.

Avamar backs up what has been written to the disk. It does not back up changes made to the file which have not yet been flushed to the disk.  

If backing up files or directories where

1. The size of the file changes

avtar Error <16507>: Path "C:\xxxxxxxx\xxxx_xx.log": Total processed bytes 5678 is inconsistent with original data size 8768"

2. The file or directory is removed - for example:

avtar Error <5137>: Unable to open "/xxxxxxxx/xxx/xxxxxxxxxxxx/xxxxx.arc" for backup (code 2: No such file or directory).

avtar Error <7553>: Specified source path "/nohup.out" does not exist; ignored

3. Avtar is unable to continue to access the file or directory.

This might result in files being rendered inconsistent. To avoid this, ensure that backups take place during periods of low activity. If necessary, use third-party software to create a snapshot of the file system and back up the contents of the snapshot.