Quick and Dirty Example here.In our last example, we created a volume
group vg03. It had thee disk, we expanded it to 4 because we planned proper
capacity.
Our volume group now consists of 4 disks.
We are asked to create an approximately 10 GB files system in this SAN based
volume group.
vgdisplay /dev/vg03
vgdisplay -v /dev/vg03
< Insert vgdisplay example here>
HP vgdisplay
documentation link (Note this tends to change. I can't help it if HP breaks
the links)
This will show an empty volume group as we have not created any logical volumes
pvdisplay /dev/dsk/c10d0t1
… repeat for other disks …
<Insert pvdisplay examples here>
HP pvdisplay
document link
Make sure nothing is on them.
Turns out 10 GB will fit quite nicely on a single disk. Since this is a SAN
based disk, we need not worry here about raid configuration. If you are hosting
an oracle rdbms, you should make sure the SAN admin sets up data, index and
rollback as raid 1 or raid 10 to insure good performance.
lvcreate /dev/vg03
# Creates an empty logical volume on vg03. Uses default naming.
You can also do it this way if you like names.
lvcreate /dev/vg03 -n mydata
lvextend -L 10240 /dev/vg03/mydata /dev/dsk/c10t0d1
# This command creates an approximately 1024 MB logical volume and defines
the disk it goes on. Always define the disk. Don't let LVM or SAM decide where
your data is going to go. Plan in advance. Note that LVM for Linux which is
a feature port and not a binary recompile does let you define size 10 GB or
10240 MB. Still waiting for that feature on LVM for HP-UX.
newfs -F vxfs -o largefiles /dev/vg03/rmydata
# Why largefiles? Databases are big and the default limit
on a file size in a file system is 2 GB. That is too small. I almost always
set up my file systems these days for largefiles unless the file system itself
is less than 2 GB
# Create a mount point.
mkdir /mydata
# mount it.
mount /dev/vg03/mydata /mydata
# This does not set an optimal JFS logging and recovery options, but that
is a different article
bdf
# See if its there and the right capacity.
Next article: Edit /etc/fstab and set permanent mount options.
NOTE: This article needs to be checked and have vgdisplay and pvdisplay and
other examples inserted into it.
Tags: forums.itrc.hp.com,
high
capacity volume group,
HP-UX, hpux,
largefiles,
lvcreate,
LVM,
newfs
Volume group creation, done right need only be done once to last
a long time. A few simple steps can make it a process you do once and
then enjoy the long term benefits.
Step one is a little homework. Take a reasonable estimate at how
many physical volumes the volume group is going to contain. Why is this
important? Because by default lvm allocates resources as if there will
be 255 physical volumes. Most volume groups don't see that many disks,
and the overall capacity is impacted by the default. For this example,
we will pick a small volume group that is never anticipated to exceed
10 physical volumes. We will set the maximum volumes to 25 to have a
fair amount of additional capacity but to more efficiently allocate
scarce resources.
Now th fun begins. We will create a volume group called vg03
Discover the new disks, important if LUNS have been presented to
the system.
insf -C disk (may not be needed on HP-UX 11.31)
ioscan -fnC disk
ioscan shows three disks for this example.
/dev/rdsk/c10t0d1 /dev/rdsk/c10t0d2 /dev/rdsk/c10t0d3
cd /dev
mkdir vg03
mknod /dev/vg03/group c 64 0×030000
# We have created a device file for the volume group.
We need to pvcreate the disks, which lablels the disk for use by
LVM
pvcreate /dev/rdsk/c10t0d1
pvcreate /dev/rdsk/c10t0d2
pvcreate /dev/rdsk/c10t0d3
vgcreate -p25 /dev/vg03 /dev/dsk/c10t0d1 /dev/dsk/c12t0d1
/dev/dsk/c10t0d3
# alternative vgcreate -e 65535 -s 16 /dev/vg10 /dev/dsk/c10t0d1
/dev/dsk/c12t0d1 /dev/dsk/c16t0d1 /dev/dsk/c17t0d1
The option -s lets us set a larger PE size which can also increase
capacity.
Now inevitably someone is going to decide to add another disk to
this volume group. It may be immediately or it may be down the road.
We are prepared.
The SAN admin and project manager want to create a scratch area within
the volume group for oracle backups to disk.
They present a new lun disk /dev/rdsk/c16t0d5
We respond like lightning.
insf -C disk
ioscan -fnC disk
pvcreate /dev/rdsk/c16t0d5
vgextend vg03 /dev/dsk/c16t0d5
The disk is ready for use.
Different article for how we set up logical volumes and a file system.
Tags: forums.itrc.hp.com,
high
capacity volume group,
hpux,
LVM
