Hi
To Check Your VMware ESX server VMFS Partition table follow the following procedure:
1- Connect to the VMware ESX server where is the missing datastore (VMFS) was connected using SSH. Make sure you have a root access.
2- Run the following command to find out your SAN devices: esxcfg-vmhbadevs
The output will look something like below:
vmhba0:0:0 /dev/cciss/c0d0
vmhba1:0:1 /dev/sda
vmhba1:0:2 /dev/sdb
vmhba1:4:2 /dev/sdc
3- If you know the SAN device that is holding the missing datastore (VMFS) then run the following command on that device to check its partition table, else run it on all the devices and check them one by one. (Hint: The command to show the partition table for all the devices is ‘fdisk -lu’)
fdisk -lu /dev/sda <== run this if you know that sda is the device holding the missing datastore (VMFS)
Output should look something like below for a LUN with the VMFS Partition table is missing:
Disk /dev/sda: 322.1 GB, 322122547200 bytes
255 heads, 63 sectors/track, 39162 cylinders, total 629145600 sectors
Units = sectors of 1 * 512 = 512 bytes
Disk /dev/sda doesn’t contain a valid partition table
or it could look something like below on some versions
Disk /dev/sde: 214.7 GB, 214748364800 bytes
255 heads, 63 sectors/track, 26108 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id
System Where a normal working entry with a valid partition table will look something like below:
Disk /dev/sdb: 16.1 GB, 16106127360 bytes
255 heads, 63 sectors/track, 1958 cylinders, total 31457280 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 (eg:128 31455269 15727571) fb Unknown <== Its your partition table entry Notice
in the last example the line of the partition table:
‘/dev/sdb1 (eg:128 31455269 15727571) fb Unknown’ <== This means the partition table exist.
If you have figured out that your VMFS partition table is missing then follow the below steps, else if your partition table exist just as in the last sample then this is not the solution for your case. If you found out this is the case, and you have VMware support I highly recommend you call them to help you recovering your partition table. As any mistake with this procedure provided can get you to loose your data permanently. If your only option is to recover on your own then the below procedure should do the trick for you as I had tried it 3 time before
VMware ESX VMFS Recovery Procedure steps: After you had found out that the affected device is /dev/sda from the procedure above, now its time to fix it. The procedure below assume /dev/sda is the defective device, please make sure to replace that with what ever device is failing in your environement when executing the below commands. As well make sure you are connected to ssh as a root. and run the below procedure. Entered commands are marked in red.
[root@vmwaretest vmhba2]# fdisk /dev/sda <== To start the fdisk (partitioning utility)
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 0×0000 of partition table 4 will be corrected by w(rite)
Command (m for help) n <== add a new partition
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-39162, default 1): Hit Enter <== Take default
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-39162, default 39162): Hit Entert <== Take default
Using default value 39162
Command (m for help): t <== Change a partition type
Selected partition 1
Hex code (type L to list codes): fb <== VMFS partiton Type
Changed system type of partition 1 to fb (Unknown)
:
Command (m for help): x <== Expert mode
Expert command (m for help): b <== Move beginning of data in a partition
Partition number (1-4): 1
New beginning of data (63-629137529, default 63): 128 <== The partition offset used for VMFS
Expert command (m for help): w <== Write table to disk and exit
The partition table has been altered!
Best regards, BharatR--VCP4-Certification #: 79230, If you find this information useful, please award points for "correct" or "helpful".
