[BBLISA] RAID Array Not Recognizing All 7TB

[John P. Rouillard]

In message <14F5FE3D-EBEA-454A-A3AD-B4A1A02383C4 at aavso.org>,
"Richard 'Doc' Kinne" writes:
>We recently upgraded a SATA RAID-5 array on one of our servers. We
>installed 8 1TB SATA drives in the system expecting to get a 7TB RAID
>array.

Is this a software raid or hardware raid? Looking below you said there
is a raid controller, but is it running in JBOD mode with software
raid, or are you using it's raid controller firmware? If the latter,
what raid controller and what firmware version.

Also what OS version/distribution?

>The server is running Fedora Core 6. The kernel is at 2.6.22.9 so we
>don't have a problem with respect to space limits. Initially when we
>initialized the RAID-5 array we set up 7 disks in the array with one
>as a hot-swap. We realized later that was not what we wanted to do,
>and thought that this might have been the reason why we were only
>getting 6TB when we thought we should be getting 7TB.
>
>We went back and believe we "expanded an existing array" so that it
>brought in the 8th disk. Once that was done it started re-
>initializing the array in the background, which we thought was fine.
>We left it to its devices and took up the job the next morning.

Ok, so you did a:

  madam --add /dev/mdX /dev/sdh
  mdadm --grow --raid-devices=8 /dev/mdX

(assuming software raid).

Also I assume somewhere in this you had to tell the raid that it no
longer had a spare disk.

>The next morning, after the array was apparently re-initilized we  
>used "parted" to manipulate the array. It still said that it only  
>recognized 6TB, not 7TB. :-( We:

I haven't used parted but did you destroy the original 6TB partition?
Are you sure you were looking at the whole disk and not just the old
6TB partition?

Thinking back to a real disk (and an md device IIRC is just another
block device), you can have multiple slices /dev/sda1, sda2 etc. I
have never seen any md device split apart like that, but...

>mklabel gpt
>mkpart 0% 100%
>print
>
>and it still said it only recognized 6TB, not 7TB.
>
>This seemed to be actual because I followed through by formatting the  
>partition to the ext3 file system and mounting it. it showed 6TB  
>ready to go.

That is consistent with working on the old 6TB partition. Is there a
way to grow a partition in parted? I know when you use LVM, you can
extend the LVM partition/container, but the ext3 file system has to be
told to grow into the additional space.

So you may have an 7TB raid container, but the raid has a 6TB
partition in it, and parted is working within that 6TB partition.

>As far as I know the RAID controller can handle 32TB, as can the
>kernel. The only thing I can think of at this point is that we need
>to start the whole thing from scratch, i.e. don't "expand an existing
>array," but re-do the array initialization completely.

I would think expanding a raid array should work.

--
				-- rouilj
John Rouillard
===========================================================================
My employers don't acknowledge my existence much less my opinions.