Creating a properly offset slab of disk for Linux systems on your CLARiiON is not just a matter of creating a partition using the default fdisk values. The reason for this is that disk management utilities for Intel based systems generally write 63 sectors of metadata directly at the beginning of the LUN. The addressable space begins immediately after these initial sectors causing the CLARiiON to cross disks, especially when writing larger IO because it doesn’t match up with the stripe element size (usually 64k).
To get around this, you have to align the partition in such a way that it will start writing data on a sector that will mesh up nicely with the stripe element size. In this case, 128. Below is an example of how I create partitions on our CLARiiON for Linux systems. Check out the EMC Best Practices for Fibre Chanel storage white paper for more detail.
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
The number of cylinders for this disk is set to 39162.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): n
p primary partition (1-4)
Partition number (1-4): 1
First cylinder (1-39162, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-39162, default 39162):
Using default value 39162
Command (m for help): x
Expert command (m for help): b
Partition number (1-4): 1
New beginning of data (63-629137529, default 63): 128
Expert command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
I’ve just returned from EMC training in MA, where we learned a wealth of information about how to use the array, but also some interesting background information about the device itself.
First, the name CLARiiON has some interesting history. Before EMC was EMC, it was Data General, who had a 16-bit minicomputer called the NOVA. DG later came up with new product which the engineers had named the NOVAII. The marketing group, not wanting to recycle the “NOVA” name, insisted that a new name be chosen. The engineers, always wanting to get their way in the end, came up with a anagram “AViiON” by reversing the letters, and cleverly placing the two “ii’s” in the middle. The CLARiiON is simply a derivative of this naming convention.
Secondly, most people know that the operating system of the CLARiiON is called “FLARE”, but it is not commonly known that this is actually an acronyms that stands for Fibre Logic Array Runtime Environment.
It is also fairly common knowledge that one can access “Engineering Mode” on a CLARiiON by pressing Ctl,shft, and f12 and entering the password “messner”. The story behind this password, however, is that the engineering group at the time were avid mountain climbers and chose the password in honor of Reinhold Messner, the first person to climb Everest without the use of oxygen. Apparently the password before that was “pink floyd”, but the marketing group didn’t approve and made them change it.
Sun Microsystems likes the QLA 2310 Fiber Channel HBA. It’s only a 2Gig card, but it works with the Sun native driver, which makes it wonderful for us Solaris Administrators. Unfortunately, it does not integrate perfectly with EMC CLARiiON SANs because it does not register properly with Navasphere. Even if you manually register the host, the LUNs will not be presented to the host because the agent can’t pass commands to the array.
To remedy this situation on my Solaris 8 host, I used the following procedure:
Edit the /etc/system file and add the following line:
Next, I rebooted my Solaris host with the “-r” flag:
reboot -- -r
Next I checked Navisphere to make sure my paths have logged in. They were, so I logged into the Solaris host and ran the following commands:
cfgadm devfsadm format
I then saw the storage that was presented to my host. Finally, I restarted the Navisphere agent and started using my new LUNs.