File systems do have limits. Thats no surprise. ext3 had a limit at 16 TB file system size. If you needed more space you´d have to use another file system for instance XFS or JFS or spilt the capacity into multiple mount points.
ext4 was designed to allow far more larger file systems than ext3. According to wikipedia ext4 has a maximum file system size of 1 EiB (approx. one exabyte or 1024 TB).
Now if you´d try to create one single large file system with ext4 on every linux distribution out there (including OEL 6.1; as of 18th August 2011) you will end up with:
[root@localhost ~]# mkfs.ext4 /dev/iscsi/test mke4fs 1.41.9 (22-Aug-2009)
mkfs.ext4: Size of device /dev/iscsi/test too big to be expressed in 32 bit susing a blocksize of 4096.
This post is about how to solve the issue.
The demo system
My demo system consists of one large LUNof 18 TB encapsulated in LVM with a logical volume of 17 TB on a Oracle Enterprise Linux (OEL 5.5):
[root@localhost ~]# uname -a
Linux localhost.localdomain 2.6.18-194.el5 #1 SMP Mon Mar 29 22:10:29 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux
[root@localhost ~]# cat /etc/redhat-release Red Hat Enterprise Linux Server release 5.5 (Tikanga)
[root@localhost ~]# fdisk -l /dev/sdb
Disk /dev/sdb: 19791.2 GB, 19791209299968 bytes
255 heads, 63 sectors/track, 2406144 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/sdb doesn't contain a valid partition table
[root@localhost ~]# vgdisplay iscsi
--- Volume group ---
VG Name iscsi
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 2
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 18.00 TB
PE Size 4.00 MB
Total PE 4718591
Alloc PE / Size 4456448 / 17.00 TB
Free PE / Size 262143 / 1024.00 GB
VG UUID tdi4f2-3ZYr-c1P0-NuSl-i3w2-5qQl-K75guj
[root@localhost ~]# lvdisplay iscsi
--- Logical volume ---
LV Name &nb