Formatting with large RAID Volume

Issues related to hardware problems

Formatting with large RAID Volume

Postby Kyle » 2011/09/30 17:55:20

Hi Everyone!

After 8 years as a system admin in a windows shop I have decided to take the plunge and put up a Centos 6 server in a data center!

My system has 6 1 TB drives configured in a RAID 5EE

That creates a 3.6 TB volume.

I have discovered that the volume created by linux and fdisk is 2.2 TB with a free space of 1.8 TB

Started reading up on this and it seems that I need to be using GPT.

From what I understand you cannot use GPT when installing CENTOS 6? My install is fresh - I have no data stored on the server yet - so if it is indeed possible I could nuke the install and start over.

I also ran across a utility called GPT fdisk. Is this the way it has to be done - that is - install using fdisk and then convert it to GPT? I assume that if you use this method you would need to then resize the 2.2 TB partition created by fdisk?

I included a screen shot of my current disk setup.


Go easy on me - remember I am a windows guy just crossing over to the dark side - not totally helpless with Linux but new to a lot of stuff - so some instructions that are easy to follow will be greatly appreciated!


Any help will be greatly appreciated!

Cheers

Kyle


:-D :-D
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Formatting with large RAID Volume

Postby TrevorH » 2011/09/30 18:52:03

The forum attachment feature is permanently broken so your picture didn't show up.

If you have a hardware RAID card, can it create more than one volume? If it can, make a smaller one to contain the operating system itself or even so small just to contain the /boot partition. Then make a second RAID drive and use that with a GPT partition or turn it into one huge LVM physical volume/volume group and you can make smaller logical volumes inside that as you need. Currently I am installing Centos 5 systems on real machines, partitioned into 200MB for /boot and the rest of the disk as an LVM volume, with a 16GB logical volume for / and a 2GB LV for swap. The rest of the space in the volume group is then available to use for other purposes. I don't have disks in these servers that are of that TB size but the same idea should work there too.
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Re: Formatting with large RAID Volume

Postby Kyle » 2011/09/30 21:50:25

Hi TrevorH


Thanks for the reply and that sounds exactly like what I want to do.

Does this give you the info you need on the Volumes? Not sure if I can create more than one volume.

# lvscan

ACTIVE '/dev/vg_host1/lv_root' [50.00 GiB] inherit
ACTIVE '/dev/vg_host1/lv_home' [1.92 TiB] inherit
ACTIVE '/dev/vg_host1/lv_swap' [33.48 GiB] inherit

# pvscan

PV /dev/sda2 VG vg_host1 lvm2 [2.00 TiB / 0 free]
Total: 1 [2.00 TiB] / in use: 1 [2.00 TiB] / in no VG: 0 [0 ]

# vgscan

Reading all physical volumes. This may take a while...
Found volume group "vg_host1" using metadata type lvm2
[root@localhost ~]#


If I go to Disk Utility - go to Adaptec PCS1 controller - Click on "Free 1.8 TB" - select Create Partition - Type Ext4 - it fails with error:

Error creating partition: helper exited with exit code 1: In part_add_partition: device_file=/dev/sda, start=2199023255552, size=1799580811264, type=
Entering MS-DOS parser (offset=0, size=3998604066816)
MSDOS_MAGIC found
found partition type 0xee => protective MBR for GPT
Exiting MS-DOS parser
Entering EFI GPT parser
No GPT_MAGIC found
Leaving EFI GPT parser
Entering Apple parser
No MAC_MAGIC found
Leaving Apple parser
No known partition table found
got it
Error: /dev/sda: unrecognised disk label
ped_disk_new() failed


Since I am pretty new to linux can you point to a step-by-step guide or assist me with the steps necessary to make this happen?

Thank!

Kyle


:-o
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Re: Formatting with large RAID Volume

Postby Kyle » 2011/10/01 01:22:13

Ok . ..

I figured it out! :lol: :lol:


Here is what I did.

Found this post on the forums here:

https://www.centos.org/modules/newbb/vi ... post141012

Here is the part from that post that I used:

open shell prompt: (Ctrl+Alt+F2)
type in "parted /dev/sdb"
mklabel gpt
reboot

Started the install.

At the point right before the installation step = "Which type of installation step would you like"

I Typed "Ctrl+Alt+F2"

Then typed "Parted"

Then typed "mklabel gpt"

There was a warning about the - correct me if I am wrong - the sdb volume being deleted.

I then hit the reset key and started the install process over.

When I got back to the installation step = Which type of installation step would you like" I picked the "Use Free Space" option.

I was then prompted to create a boot loader - I choose the default option given.

The installation continued and I ended up with a 3.9 TB volume. Sweet!

When I click on the adapter in Disk Utility it shows:

Device: /dev/sda1
Type Ext4
Capacity 524 MB

Device: /dev/sda2
Type Linux LVM Partition
Capacity 4.0 TB

Excellent. Been here since 6 AM - now 7:20 PM

Guess I can brush my teeth now and take a shower!

Woot!
Kyle
 
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Re: Formatting with large RAID Volume

Postby TrevorH » 2011/10/01 01:44:13

Well that works but it wasn't quite what I meant. But if it works, it works.

Where I'd intended you to end up was in the array creation bit of the RAID controller, delete the entire array that you had and create two new ones. The first array would be small and the second the rest of the space. Those two arrays would then have shown up as /dev/sda and /dev/sdb and you'd have used the first to install on and the used the second later to create an LVM PV/VG/LV.
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Re: Formatting with large RAID Volume

Postby Kyle » 2011/10/01 02:25:19

Hi TrevorH

I did understand what you wanted me to do but I was not sure how to do it.

That is, install on the 1st raid array and then "later to create an LVM PV/VG/LV."

Anyway, its done . . . .

:-D
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