[linux-lvm] large logical volumes

[Guido Vettoretti <g.vettoretti@utoronto.ca>]

Hello,

I'm trying to set up a large logical volume (13.1 TB) on a RHEL 4.0 
server. I have 8 scsi devices of 1.8Tb each.

When I try to do a 'mkfs' and set up a large disk I get limited to 4Tbytes.
This command creates a smaller filesystem then
[root@cyclone ~]# lvcreate -l 1287525 -i 3 -n lvol0 vol0
this one.
[root@cyclone ~]# lvcreate -l 1000000 -i 3 -n lvol0 vol0

It seems that there is a limit on the number of  block groups of 32768 
and blocks per group of 32768.
My block size is 4096
so I can only get an LV of 4096*32768*32768 = 4TB.

I tried modifying the PE size on the volume group, but I'm still having 
problems.

Can anyone help please?

Thanks
Guido
---------------
[root@cyclone ~]# mkfs -t ext3 /dev/vol0/lvol0
mke2fs 1.35 (28-Feb-2004)
max_blocks 4294967295, rsv_groups = 0, rsv_gdb = 1024
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
512016384 inodes, 1024002048 blocks
8250429 blocks (0.81%) reserved for the super user
First data block=0
Maximum filesystem blocks=1027604480
31251 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, 550731776, 644972544


Here is the entire process I typed:
------------------------------------------------------------------------------

[root@cyclone ~]# pvcreate /dev/sdc1 /dev/sdd1 /dev/sde1
  Physical volume "/dev/sdc1" successfully created
  Physical volume "/dev/sdd1" successfully created
  Physical volume "/dev/sde1" successfully created
[root@cyclone ~]# pvscan
  /dev/cdrom: open failed: No medium found
  PV /dev/sda2   VG VolGroup00   lvm2 [34.06 GB / 0    free]
  PV /dev/sdb1   VG VolGroup00   lvm2 [34.16 GB / 0    free]
  PV /dev/sdc1                   lvm2 [1.64 TB]
  PV /dev/sdd1                   lvm2 [1.64 TB]
  PV /dev/sde1                   lvm2 [1.64 TB]
  Total: 5 [4.98 TB] / in use: 2 [68.22 GB] / in no VG: 3 [4.91 TB]
[root@cyclone ~]# vgcreate vol0 /dev/sd[c-e]1
  Volume group "vol0" successfully created
[root@cyclone ~]# vgdisplay
  --- Volume group ---
  VG Name               vol0
  System ID            
  Format                lvm2
  Metadata Areas        3
  Metadata Sequence No  1
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                3
  Act PV                3
  VG Size               4.91 TB
  PE Size               4.00 MB
  Total PE              1287525
  Alloc PE / Size       0 / 0  
  Free  PE / Size       1287525 / 4.91 TB
  VG UUID               fQ7cKh-FVnl-NglQ-jimv-RsZK-dU5j-zYKIcG

[root@cyclone ~]# lvcreate -l 1287525 -i 3 -n lvol0 vol0
  Using default stripesize 64KB
  Logical volume "lvol0" created
[root@cyclone ~]# lvdisplay
  --- Logical volume ---
  LV Name                /dev/vol0/lvol0
  VG Name                vol0
  LV UUID                c2MADb-BoAO-lhl3-3ukj-XfyQ-K8L0-cxcIlw
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                4.91 TB
  Current LE             1287525
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:2
  
[root@cyclone ~]# mkfs -t ext3 /dev/vol0/lvol0
mke2fs 1.35 (28-Feb-2004)
max_blocks 4294967295, rsv_groups = 0, rsv_gdb = 1024
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
122355712 inodes, 244683776 blocks
12234188 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=247463936
7468 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