We had problems related to partitions tables. We used gparted to create 
a "gpt" partition table instead of the standard "msdos". Unfortunately 
fdisk does not recognize gpt partition tables, so you need to use other 
tools.

Our experience with a 8TB ext3 filesystem takes 10-12hrs for fsck & 
similar times for quotacheck (depends on speed of hardware, etc). We 
ended up using 4TB filesystems to reduces maintenance times.

> Our local vendor built us a Supermicro/Adaptec
>> system with 16x1TB SATA drives.  We have a 12TB
>> partition that they built as EXT2.  When I tried
>> to add journaling, it took forever, and then the
>> system locked up.  On reboot, the FS was still
>> EXT2, and takes hours (even empty) to fsck.  Based
>> on the messages flying by I am also not confident
>> fsck rally understands a filesystem this large.