Hi,

I need to know if 18TB file system is possible in RHEL 5.5
I know that ext3 file system size limit is 16TB and LVM decide can go upto 8EB but if i create LVM of 18TB, i still have to create ext3 file system on it which is limited to 16TB

am i missing something ?

also, what are the disadvantages of creating such as large file system? is chkdsk type facility going to take forever?

According to Red Hat, you would be looking at XFS or GFS2 to get 18TB.

LVM is your disk partition, ext3 is your filesystem. Compare LVM to adding a 18TB HDD and/or SAN LUN and then needing to put a filesystem on it to actually use it. Unless of course whatever application has it's own proprietary filesystem and can handle direct I/O (like oracle ASM).

in terms of disadvantages, it depends on what you are putting on there. A single large DB on an 18TB LUN shouldn't cause any problems. An 18TB LUN full of tiny files will create a big headache.

As for chkdsk, you could really say any application/tool that needs to access many of the blocks will take forever. It is a function of your disk speed.

Don't forget to consider how you will back it up too.

Ask yourself if you really NEED 18TB in a single volume, would you be better served having smaller volumes on different mount points?