Recovering unused hd space: Server

vshell · 05-15-2006, 03:07 PM

I work for a small shop that has decided to move to Linux. So we ordered this big server from Dell with Redhat Linux pre-installed. It's got 6 drives and 1.5 Tb of storage space, all striped to RAID 5. In checking it out I discovered that for whatever reason, Dell shipped it with 1.4 Tb unformatted. Naturally, we'd like to use this space. Using Logical Volume Management in the GUI tools I have attempted to initialize this partition (/dev/sda4) but get the warning that data from directory /boot will be destroyed. In fact, this partition is mounted on /boot and du reports that it's using 237Mb out of a total 4 Gigs.

I may be a newbie, but it strikes me as a bad idea to wipe out data belonging to /boot. I'm a little unclear too on how /boot could be using this space if there's no filesystem installed. So can I move the data and proceed with creating a new logical volume?

Any help would be greatly appreciated.

WhatsHisName · 05-15-2006, 05:44 PM

Yes, overwriting /boot is a bad idea.

If you would like some suggestions, it would be helpful to post the output of the following commands:

Code:

# df -h
# fdisk -l
# pvscan
# lvscan

vshell · 05-16-2006, 12:34 PM

Thanks for offering to help. Here's the output you requested:

#df -h

Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
4.0G 237M 3.6G 7% /
/dev/sda3 4.0G 237M 3.6G 7% /boot
/dev/sda4 4.0G 237M 3.6G 7% /boot
none 2.0G 0 2.0G 0% /dev/shm
/dev/mapper/VolGroup00-LogVol05
4.0G 41M 3.7G 2% /home
/dev/mapper/VolGroup00-LogVol03
4.0G 41M 3.7G 2% /tmp
/dev/mapper/VolGroup00-LogVol02
7.9G 2.6G 5.0G 35% /usr
/dev/mapper/VolGroup00-LogVol04
4.0G 148M 3.6G 4% /var

#fdisk –l

Disk /dev/sda: 1499.8 GB, 1499883110400 bytes
255 heads, 63 sectors/track, 182350 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 1 12 96358+ de Dell Utility
/dev/sda2 13 535 4200997+ 8e Linux LVM
/dev/sda3 * 536 560 200812+ 83 Linux
/dev/sda4 561 182350 1460228175 5 Extended
/dev/sda5 561 182350 1460228143+ 8e Linux LVM

Disk /dev/sdb: 259 MB, 259522560 bytes
16 heads, 32 sectors/track, 990 cylinders
Units = cylinders of 512 * 512 = 262144 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 * 1 991 253439+ 6 FAT16
Partition 1 has different physical/logical endings:
phys=(989, 15, 32) logical=(990, 0, 31)

#pvscan

PV /dev/sda5 VG VolGroup00 lvm2 [1.36 TB / 1.33 TB free]
PV /dev/sda2 VG VolGroup00 lvm2 [4.00 GB / 4.00 GB free]
Total: 2 [1.36 TB] / in use: 2 [1.36 TB] / in no VG: 0 [0 ]

#lvscan

ACTIVE '/dev/VolGroup00/LogVol00' [4.00 GB] inherit
ACTIVE '/dev/VolGroup00/LogVol05' [4.00 GB] inherit
ACTIVE '/dev/VolGroup00/LogVol03' [4.00 GB] inherit
ACTIVE '/dev/VolGroup00/LogVol02' [8.00 GB] inherit
ACTIVE '/dev/VolGroup00/LogVol04' [4.00 GB] inherit
ACTIVE '/dev/VolGroup00/LogVol01' [2.00 GB] inherit

I look forward to your insights.

WhatsHisName · 05-16-2006, 02:36 PM

The 4GB /boot is a bit odd, but otherwise, everything looks OK.

If it were my system, I would play/learn with it for a while and then reinstall the OS in a more logical manner.

The system is set up using Logical Volume Management v.2 (LVM2) and there’s lots of space available. With LVM, you add space to the logical volumes as you need it or add more logical volumes as your needs change, so it’s OK that most of the array is unused.

You should read about LVM before making any modifications. The main guide is the LVM HowTo, with the “Common Tasks” and “Recipes” sections being very helpful for the first time LVM user:

LVM HowTo: http://www.ibiblio.org/pub/Linux/doc...LVM-HOWTO.html

LVM Common Tasks: http://www.ibiblio.org/pub/Linux/doc...tml#commontask

LVM Recipes: http://www.ibiblio.org/pub/Linux/doc...O.html#recipes

One warning: Stay away from the LVM GUI config and do all LVM management from command line.

**********

One important thing to remember with LVM is that when you make a logical volume larger, you then need to make the filesystem it holds larger if you want to make use of the extra space.

Likewise, when you want to make a logical volume smaller, you need to first reduce the size of the filesystem before you shrink the logical volume.

Keep in mind that when you are new to LVM, it’s relatively safe to increase the size of a logical volume and potentially unsafe to reduce the size of a logical volume.

Also, when you resize an ext3 filesystem, it should be unmounted.

vshell · 05-16-2006, 03:53 PM

WhatsHisName,

Thanks a bunch for your patience and advice. You're right, I need to come up to speed on LVM and with the HowTo and your caveats I'm on my way. It's good to know there's a place like this to get uncritical help.

My first experience here has been a good one. I may be back.