Slow SMS performance against Linux file systems using a LUM enabled backup user

  • 7006642
  • 16-Aug-2010
  • 27-Apr-2012

Environment

Novell Open Enterprise Server 2 (OES 2) Linux Support Pack 2

Situation

Backups of traditional Linux file systems (EXT3, ReiserFS etc.) are markedly slower compared to the Novell Storage Services (NSS) file system.

Resolution

There are two possible solutions to this;

1. Use the ROOT user when scheduling the backups of the traditional Linux file systems (preferred).
2. Grant the LUM (Linux User Management) enabled backup user, for example ADMIN, full POSIX rights to the relevant directories located on the traditional Linux file systems.

Exactly how to use ACL's etc. to adjust the POSIX rights are beyond the scope of this document.

Additional Information

The slower performance is due to the SMS open mode being passed in by backup applications. The default open mode requires full POSIX rights in order to read files properly for backup. If the user used for the backups do not have full rights, which ADMIN or other LUM users normally do not have by default, an error is reported for each file (FFFDFFF5 - NWSMTS_DATA_SET_IN_USE), which accounts for the slower performance.

To test if this is the case for the slowness do the following;

1. Run the tsatest utility against a traditional Linux file system path (using first the ROOT user then a LUM user to authenticate) and compare the performance. For example "/opt/novell/sms/bin/tsatest --path /etc/ -u ROOT".

The above command will run a backup read test against /etc as the ROOT user.

2. Temporarily grant all users full POSIX rights to a directory structure located on a traditional Linux file system then run tsatest against this directory path using a LUM enabled user. The following command for example will grant all users full rights to a specific path and below"chmod -R 777 /<file_path>/"