Volume management

This HOWTO describes the most basic steps in defining a striped set of DASDs for Linux on System z. The following steps create a striped volume with stripe size 64k on the DASDs /dev/dasdv1 and /dev/dasdw1. We assume that the used DASDs have already been formatted and partitioned.

1. Create "physical volumes" with the command pvcreate
   

   pserver10:~ # pvcreate /dev/dasd/56c5 /dev/dasd/56c6
pvcreate -- physical volume "/dev/dasdv1" successfully created
pvcreate -- physical volume "/dev/dasdw1" successfully created


2. Create a "volume group" with the command vgcreate
   

   pserver10:~ # vgcreate myvolgroup /dev/dasdv1 /dev/dasdw1
vgcreate -- INFO: using default physical extent size 4MB
vgcreate -- INFO: maximum logical volume size is 255.99 Gigabyte
vgcreate -- doing automatic backup of volume group "myvolgroup"
vgcreate -- volume group "myvolgroup" successfully created and activated


3. Get the maximum number of extents with the command vgdisplay
   

   pserver10:~ # vgdisplay myvolgroup
--- Volume group ---
VG Name myvolgroup
VG Access read/write
VG Status available/resizable
VG # 0
MAX LV 256
Cur LV 0
Open LV 0
MAX LV Size 255.99GB
Max PV 256
Cur PV 2
Act PV 2
VG Size 13.74GB
PE Size 4MB
Total PE 3518
Alloc PE / Size 0 / 0
Free PE / Size 3518 / 13.74GB
VG UUID hNoJPC-N3a0-g7md-dK64-PwJ7-T1De-Y0jF7V


4. Create the "logical volume" with the command lvcreate
   

   lvcreate --name mylvolume --stripes 2 --stripesize 64 --extents 3518 myvolgroup
lvcreate -- doing automatic backup of "myvolgroup"
lvcreate -- logical volume "/dev/myvolgroup/mylvolume" successfully created


5. Create a file system on the created logical volume
   

   pserver10:~ # mke2fs -j /dev/myvolgroup/mylvolume
mke2fs 1.28 (31-Aug-2002)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
1802240 inodes, 3602432 blocks
180121 blocks (5.00%) reserved for the super user
First data block=0
110 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

Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 29 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.


Note that the first step of the LVM-HOWTO (http://tldp.org/HOWTO/LVM-HOWTO/):
1. Set the partition system id to 0x8e on /dev/sdc1 and /dev/sde1.
is obsolete for DASD devices on Linux on System z (but valid for SCSI disks)

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