[linux-lvm] large logical volumes
Myrddin Emrys
myrddin at gmail.com
Fri Apr 29 20:00:43 UTC 2005
Looks like you never got a response. I hardly consider myself
qualified, but have you considered increasing the block size? The
other option, have you tried a different filesystem? Different fs have
different limitations... what you're describing appears to be a
limitation of ext2fs, not LVM. Have you considered XFS or ReiserFS?
On 3/30/05, Guido Vettoretti <g.vettoretti at utoronto.ca> wrote:
> 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 at cyclone ~]# lvcreate -l 1287525 -i 3 -n lvol0 vol0
> this one.
> [root at 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 at 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 at 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 at 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 at cyclone ~]# vgcreate vol0 /dev/sd[c-e]1
> Volume group "vol0" successfully created
> [root at 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 at cyclone ~]# lvcreate -l 1287525 -i 3 -n lvol0 vol0
> Using default stripesize 64KB
> Logical volume "lvol0" created
> [root at 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 at 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
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
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