Topic: 2TB and RAID 5 problem

[stdean]

I'm not entirely which is giving me my problem, and I've seen similar problems reported in the forums and in the FAQ, but I cant seem to find a suitable solution to my problem.

I'm currently attempting to install SME 7.2 on a new Dell Poweredge 2950. I have a PERC 5/i RAID controller with 4 750GB disks giving me just over 2TB or storage.

I have configured my RAID array to use all disks and initialized it properly. I have then (seemingly) installed SME onto the machine. The install process takes  while as it has to reformat the disks and takes about 30 mins total. I get the usual end of install message of please eject and reboot.

Upon booting though it dies completely with a kernel panic and messages along the lines of 'mdadm no devices found on xxxxx' and and 'ext3_get_inode_loc' error.

I understand that there is an issue with device over 2TB, but I thought that you would not be even able to format it to begin with.

I can post more details of the errors I'm getting if anyone needs more details.

Any help appreciated.

Conor

[Daniel B.]

I have installed SME on the same raid card (perc5i) with different disk (up to a big raid 5 array of 9x750GB + 1x750 in hot spare which gives me a total of about 5.5TB). It runs without problem. You should try to install it without raid support (as it'll be handled by your hardware, you don't need a degraded soft RAID).

Try to install with the option:

sme noraid

at boot prompt of the install CD.

[stdean]

Right, well I think I've managed to fix the problem. I'd actually tried it with 'sme noraid' but that didn't give me any joy. From the looks of things it was down to the > 2TB limitation.

For posterity (and so that I can remember the next time) I'll jot down here what I had to do.

a lot of this was pulled from http://bugs.contribs.org/show_bug.cgi?id=1963#c2 I had to do a lot of digging to figure out what most of the necessary commands were though.

In the RAID BIOS I created a Virtual Disk and made it 100GB (I dont think the size really matters, I just picked 100).

Once this was initialized I installed the OS onto this with no problems.

Once everything was all set up I had to install 'parted' (yum install parted)

I then went back to the RAID BIOS config and created a new Virtual Disk, this time taking up all the remaining space (approx 1.9TB).

Using parted now I could partition the new device. Here's what I had to do

Code: [Select]

# parted /dev/sdb

(parted) mklabel gpt
(parted) mkpart
selected default [primay]
selected default [ext2]
(parted)start: 0
(parted)end: -1

this created the new partition covering the whole device.

Which the new device /dev/sdb1 created I now had to merge this into the existing LVM.

I used lvm to do this:

Code: [Select]

# pvcreate /dev/sdb1
# lvm
lvm> vgextend main /dev/sdb1
lvm> lvextend -L2000G /dev/main/root

(I'll have to run over this later as I'm sure I'm missing about 50GB from the device somewhere).

The tricky part was figuring how to resize the filesystem whilst it was still mounted, I wanted to keep everything simple and just add the new space to the / partition, and it's not so easy to umount this. Luckily ext2online was created for this exact purpose.

Code: [Select]

# ext2online /dev/main/root

20 minutes later and I have a newly resized filesystem showing my new 2TB disk

Code: [Select]

Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/main-root
                      2.0T  1.1G  1.9T   1% /
/dev/sda1              99M   13M   82M  14% /boot
none                 1014M     0 1014M   0% /dev/shm

Hope someone else can find this useful. I'll give it a try again tomorrow with the 'noraid' option as well as the LVM approach.

Conor