[ubuntu] Fsck after boot ?

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http://ubuntuforums.org – I have a relatively new install of Ubuntu 9.10. I have two hard drives /dev/sda1 & /dev/sdb1 both ext3. Today for the first time a filesystem check was run on /dev/sdb1 but it ran after boot instead of before. I thought filesystem checks had to run in read only mode, before the filesystem was mounted. In all previous Ubuntu versions fsck runs before boot and the system boots after it has completed. Is this a new method for fsck implemented in Karmic ? (Hardware)