ESX luns allocated on Symmetrix will not format.

20 pts.
EMC Symmetrix
VMware ESX
Recently we allocated Symmetrix space for an ESX cluster. Some of the LUNs format fine but one or two come up with an error message that says "unable to read partition information from this disk." All of the luns were exactly the same capacity. The ESX is currently attached to a Symmetrix array as well as a Clariion array.

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This happens here/there and it’s just a matter of resetting the partition table, a new DOS label of the LUN(s) producing the error.

Here’s a walk-thru of fixing this issue for LUN ID 6, /dev/sda.

[root@esx1 root]# vmkpcidivy -q vmhba_devs
vmhba0:0:0 /dev/cciss/c0d0
vmhba3:0:6 /dev/sda
[root@esx1 root]# fdisk /dev/sda

Command (m for help): p

Disk /dev/sda (Sun disk label): 30 heads, 64 sectors, 36826 cylinders
Units = cylinders of 1920 * 512 bytes

Device Flag Start End Blocks Id System
/dev/sda3 u 0 36826 35352960 5 Whole disk
/dev/sda8 u 0 36826 35352960 f Unknown

Command (m for help): m
Command action
a toggle a read only flag
b edit bsd disklabel
c toggle the mountable flag
d delete a partition
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition’s system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)

Command (m for help): o
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 36826.
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
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
[root@kdcesxcoflb01 root]# fdisk -l /dev/sda

Disk /dev/sda: 289.6 GB, 289627176960 bytes
255 heads, 63 sectors/track, 35211 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
[root@esx1 root]#

After this is reset, you will be able to format the LUN with VMFS.

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