Greetings. We've got a new Dell PowerEdge (PE) 2950 server with a Dell
MD 1000 external storage array attached. The PE 2950 is running
Scientific Linux 5.0 with all patches installed:
[root@ucdsys ~]# cat /etc/redhat-release
Scientific Linux SL release 5.0 (Boron)
[root@ucdsys ~]# cat /proc/version
Linux version 2.6.18-8.1.8.el5 ([log in to unmask]) (gcc
version 4.1.1 20070105 (Red Hat 4.1.1-52)) #1 SMP
Thu Jul 12 15:15:31 EDT 2007
The MD 1000 is attached via a PERC 5/E controller. The MD 1000 has 15
750GB SATA disk drives, arranged into two virtual disks, each containing
7 physical disks (with one global hot spare). The size of each virtual
disk is 4.089TB. Please see the appended for more details.
The two virtual drives appear in, say, fdisk as sdb and sdc, both of
size 4497.6 GB. I'm a little confused by the fdisk output, which does
show the 4GB size in the header but shows 2147480811 blocks as the size
of the one and only partition. Again, see the appended for details.
We have a problem in that we're unable to make the operating system see
more than 2TB in these disks when we make ext3 file systems and mount
the devices.
The wikipedia article about ext3 claims that there are size limitations
but that with a block size of 4096 (the default), the limits are 2TB per
file and 16 TB per file system.
Evidently I'm missing something basic here. Can anybody enlighten me?
Thanks.
- Mike
Some details from the PERC 5/E set-up program
---------------------------------------------
PERC 5/E
Disk Group 0
Virtual Disk 0
RAID Level 5
Size: 4.089TB
Physical Disks
00 714880MB
.
.
.
06
Disk Group 1
Virtual Disk 1
RAID Level 5
Size: 4.089TB
Physical Disks
07 714880MB
.
.
.
13
###### fdisk seems to see 4TB per device
[root@ucdsys ~]# fdisk -l
.
.
.
Disk /dev/sdb: 4497.6 GB, 4497636065280 bytes
255 heads, 63 sectors/track, 546806 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 1 267349 2147480811 83 Linux
Disk /dev/sdc: 4497.6 GB, 4497636065280 bytes
255 heads, 63 sectors/track, 546806 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdc1 1 267349 2147480811 83 Linux
###### put a file system on the first device (4kb block size)
[root@ucdsys ~]# mke2fs -j /dev/sdb1
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
268435456 inodes, 536870202 blocks
26843510 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
16384 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632,
2654208,
4096000, 7962624, 11239424, 20480000, 23887872, 71663616,
78675968,
102400000, 214990848, 512000000
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 24 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
###### Mount the new file system and examine its size
[root@ucdsys ~]# mount /dev/sdb1 /backup1
[root@ucdsys ~]# df -h /backup1
Filesystem Size Used Avail Use% Mounted on
/dev/sdb1 2.0T 199M 1.9T 1% /backup1
###### Only 2TB! But fdisk does report
[root@ucdsys ~]# fdisk /dev/sdb
The number of cylinders for this disk is set to 546806.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Command (m for help): p
Disk /dev/sdb: 4497.6 GB, 4497636065280 bytes
255 heads, 63 sectors/track, 546806 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 1 267349 2147480811 83 Linux
Excerpt from wikipedia article about ext3:
-----------------------------------------
Size limits
ext3 has a relatively small maximum size for both individual files and
the
entire filesystem. These limits are dependent on the block size of the
filesystem; the following chart summarizes the limits[5]:
Block size Max file size Max filesystem size
1KiB 16GiB 2TiB
2KiB 256GiB 8TiB
4KiB 2TiB 16TiB
8KiB 16TiB 32TiB
The 8KiB block size is only available on architectures (such as alpha)
which
allow 8 KiB pages.
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