Reparse point is saved as a directory for Windows path backup without Volume Shadow Copy Service (VSS)

Wed, 17 Apr 2024 13:50:00 GMT

Problem: In case of a Windows path backup without using the 'Backup with VSS' option, Windows reparse points are sometimes incorrectly backed up as directories.

Windows reparse points are mainly used for symbolic NTFS links, directory connection points, volume mount points and Unix domain sockets
(see also https://en.wikipedia.org/wiki/NTFS_reparse_point).

If using a Microsoft volume with data deduplication, which internally uses special reparse points for deduplication, this behavior may result in the files' contents not being backed up.

This issue only occurs when running a Windows path backup and the option 'Backup with VSS' has been deselected in the backup properties.

Solution: Enable option 'Backup with VSS' to execute Windows path backup of NTFS or ReFS volumes. For more details, see Known Issues.

Warning: On Linux Clients, changed processing of regular expressions may impact backup sizes

Thu, 11 Jul 2024 16:07:00 GMT

Problem description: With update to Apollon V2 (5.1.0.14), the exclude lists on Linux may no longer work as intended, causing backups to be larger than expected. For Linux Clients, in backup tasks or SBC exclude lists, the changed interpretation of regular expressions can lead to backups containing data that should have been excluded. This affects complex regular expressions with escaped metacharacters (), or |.

Cause: In 5.1.0.14 Apollon V2, for SEP sesam Linux SBC, the GNU findutils were replaced by Perl-compatible Regular Expressions (PCRE), which changes how metacharacters are handled. Some metacharacters are no longer escaped with a backslash, instead, a backslash causes them to be treated as literal characters: \( \) is now interpreted as ( ) and \| is now |.

With GNU findutils syntax, grouping was performed using backslashes followed by parentheses, for example, \( and \), and the alternation operator was represented as \|.

With the update to Perl-compatible Regular Expressions (PCRE), the meaning of metacharacters escaped with a backslash is reversed for some characters. The expressions \( \) now become ( ), and \| become |. This change affects how regular expressions are interpreted and applied on Linux Clients and can therefore result in larger backup size.

Solution: On Linux clients, review your exclude lists and, if necessary, update the regular expressions to use the PCRE syntax.Check your exclusion patterns in SEP sesam Linux backup tasks, in the client sm.ini file section [SBC_EXCLUDE] and the SBC exclude list files referenced in the SBC with the option -X {excludelist_file}, and remove the backslashes that are used to escape the metacharacters, the leading '\' from \(, \) or \|. For more information, refer to SEP sesam wiki article Exclude with Regular Expressions and Creating Exclude Lists.

To convert the regular expressions in exclude_list files from GNU findutils into PCRE, you can use the following command:

sed -e 's@\\(@(@g' -e 's@\\)@)@g' -e 's@\\|@|@g' <exclude_list file>

where <exclude_list file> is the path to the file, for example, /home/sesam/exclude_list_for_backup_task_A.txt

Example

SEP sesam version 5.1.0 Apollon and older - GNU findutils default regular expression:

     \./sapmnt/\([A-Z][0-9][0-9]\|[A-Z][A-Z][A-Z]\|[A-Z][A-Z][0-9]\)/global/.*BDCLG$

SEP sesam version Apollon V2 (5.1.0.14) and newer - PCRE extended regular expression:

     \./sapmnt/([A-Z][0-9][0-9]|[A-Z][A-Z][A-Z]|[A-Z][A-Z][0-9])/global/.*BDCLG$

Note

SEP sesam Windows clients already use the Perl-compatible regular expression syntax (PCRE), so no changes are required.

5.1 (en)

Reparse point is saved as a directory for Windows path backup without Volume Shadow Copy Service (VSS)

Warning: On Linux Clients, changed processing of regular expressions may impact backup sizes