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Nov 03, 2009 at 08:37 AM

Usage of ext3 Fileystems in SAP environements


Hi all,

SAP Note 405827 "Journaled file system and raw devices on Linux" gives approval for the installation of SAP Systems based on Linux (in our case RedHat 5) and Oracle with ext3 filesystems.

When creating the journal the values for the check of the Filesystem against the Journal are set automatically:

+vmrhel5n01:~ # tune2fs -j /dev/sdb+

+tune2fs 1.38 (30-Jun-2005)+

+Creating journal inode: done+

+This filesystem will be automatically checked every 36 mounts or+

+180 days, whichever comes first. Use tune2fs -c or -i to override.+

Unfortunately I did not find any recommendation how to set this parameter (count of mounts or time value) - neither in the SAP Note mentioned above nor in the SDN.

In an high available environment it would be worse if the check was performed after a reboot of the machine for all filsystems and so delaying the start of the sap instance.

In my opinion there are several possibilities for the configuration in SAP enviroments:

1) Don't change the default setting: This should only be the right choise, if the time for the check is negligible even for large databases / filesystems and the feared start-delay won't occur.

2) Deacativate the regular checks (eg. by setting very large values).

3) Choosing diffrent values for each sapdata filesystem. Implementing that would result that after a reboot/remount only one Filesystem is checked, whereas the check-count for all other sapdata-filesystems is not reached yet.

Which of the three possibilities would you prefer? Is there another one? To which value would you set the parameters?

Thanks in advance