Topic: LUN-support in SME Server 7.4?

[hytekk]

I have installed the SME Server 7.4 a few months back and everything has been working out great until now...

Here is the short, short story:

I recently bought a DROBO ("big USB-harddrive", http://www.drobo.com/products/drobo.php) as to exapnd my possibilities to grow in storage and redundancy.
I have inserted 4*1 TB harddrives and based on the practical problems (many kernels only support block devices up to 2TB, the practical limit is 2TB) I have created 2 LUNs of 2 TB each instead of 1 with 4 TB (its not possible to create larger LUN-sizes with linux-filesystem (ext2).
If i connect DROBO, via USB, to my newly installed Ubuntu 9.10-laptop it gets automounted as if I have 2 external installed USB-drives (Drobo1 and Drobo2) but on the SME Server I can only see one of the 2 LUNs.

So my question is, how is it possible for me to mount both LUNs to SME Server?

Thanks,
alexander

[wires12]

Back when 1Tb drives were $$$ I used several Promise ATA to SCSI external RAID boxes. Using a How-To I symlinked i-bays off to a large disk. I worked GREAT for me. While the original How-To seems to be MIA here I found it at http://distro.ibiblio.org/pub/linux/distributions/smeserver/contribs//mblotwijk/HowToGuides/AddExtraHardDisk.htm check out step 6.

I just found the new version! wiki.contribs.org/AddExtraHardDisk It seems to have more details...

[hytekk]

Thanks for your answer.

The problem is that the "second drive" never shows up, I cannot mount in my SME Server. Yet on my laptop, running ubuntu 9.10, it automagicly mounts both LUNs ("both USB-disks").

/alexander

[Stefano]

is there anything interesting in the logs? (/var/log/messages)

[hytekk]

Not really

Only one of the "disks" presents.

Running "cat /sys/module/scsi_mod/max_luns" shows "1".

I am now trying to echo in 2... rebooting now and lets see if it works....

No, not working. "cat /sys/module/scsi_mod/max_luns" still shows "1"....

[Stefano]

mmmhhh.. unplug your hds, echo in 2 and plug in again..

[slords]

just export the entire 4TB as one volume.  Create LVM on top of it and then create logical volumes of the size you need and format it.  I've done this for a 12TB and a 8TB raid set and it works fine.  Also you can create an ext3 larger then 2TB without issue.  I've got a few 4TB and several 3.5TB lvs that run just fine.

[hytekk]

Ok, I am back after trying several methods...

* Tried unmounting all my USB-drives, echoed in 2 - "echo "2" > /sys/module/scsi_mod/max_luns".
* Rebooted, with only Drobo connected via USB.
* Still the problem persists. Running the command cat /sys/module/scsi_mod/max_luns gives me 1 and not 2....

Have read some howtos, googled around and came across this http://support.datarobotics.com/app/answers/detail/a_id/23 and read this:

File System Format    Compatible With Max      Volume Size
"EXT3                      DroboShare, Linux          2TB**

** EXT3 is supported only for volume sizes of 1TB or 2TB. However, customers have found that they are able to have volume sizes (LUNs) greater than 2TB by attending to two items:

    * Ensuring the Linux kernel is 2.6.24 or greater
    * Enabling the selection "Enable Block Layer-->Support for Large Block Devices"

And since I am running a 2.6.9-78.0.22.EL-kernel I cant seem to get this thing to work properly.

I have also read this;
GPT support must be enabled in your Linux distribution.

And by running fdisk -l I get this message at the end;

WARNING: GPT (GUID Partition Table) detected on '/dev/sde'! The util fdisk doesn't support GPT. Use GNU Parted.


Disk /dev/sde: 2199.0 GB, 2199023185920 bytes
255 heads, 63 sectors/track, 267349 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sde1               1      267350  2147483579+  ee  EFI GPT


And ideas?

/alexander

[CharlieBrady]

And ideas?

Use GNU parted, as fdisk told you.

[christian]

Ok, I am back after trying several methods...

And ideas?

I just tried this myself in various forms (large 8.0TB LVM and 5x1.0TB RAID5) with no issues.
First ext3 does support more than 2.0TB, I believe you can currently go to 32TB.

My best guess as to your issue is that the Drobo device is MUXing the LUNs on your serial interface but the current linux driver you are using may not know how to present that. If this is the case then you may need to either:
a) load an appropriate driver onto your system to demux
b) if the drobo can assemble and present as one disk then Shad's suggestion would be the easiest.

Note in method (b) the drobo unit should end up presenting the entire disk set as the first LUN hence you avoid the demux.

Christian