How can I determine disk alignment? (FDISK, VMKFSTOOLS, etc.)

[ascheler]

How can I determine if my VMFS volumes have been correctly "aligned"? I have documentation on "how to align" (apparently by using VC which automatically aligns VMFS partitions, using FDISK, or using VMKFSTOOLS). But I am struggling with assessing whether or not the "alignment" was successful or whether or not the alignment was correctly performed previously. I do not know how to use a tool to "view" the current state of alignment on a VMFS volume. Any help would be appreciated.

Thank you.

Alex.

[cobalt128]

Hi Ascheler,

Same story for me.

Any clues group ? Please share

Mark

[VirtualKenneth]

Interesting question since I normally just "believe" that this is being done correctly.

[davidbarclay]

Agreed.

I read all the guff on how "it's handled" these days. never thought to check it out for myself.

Time to search Vmworld pdfs I think.

Dave

[davidbarclay]

TAC0161 says to leave it to VC, but doesn't mention a tool to check.

Dave

[davidbarclay]

Remembered this doc

http://www.vmware.com/pdf/esx3_partition_align.pdf

....but my room serivice just arrived, so you will need to skim it yourself

I'll check back soon.

Dave

[VirtualKenneth]

Room Service?, I assume there isn't a VMware Event somewhere that I missed right?

[davidbarclay]

nahhhhh, I'm in Australia.

It's 8:20pm. I just finished another long day on a VMware project away from home and I am catching up on the forums in my hotel room, sipping on a Jameson's and \_now_ am eating some room service

Dave

[VirtualKenneth]

Aaah, good stuff... enjoy your meal!

[Baz]

Hi,

To check alignment of the VMFS volume, follow steps below:

1 To view the list of luns and paths, type: vmkmultipath -q

2 Note the lun id you wish to check. eg vmhba1:0:2

3 Type: vmkpcidivy -q vmhba_devs

4 In the list, note the /dev/sdx value for the relevant lun. (in the example below, vmhba1:0:2 is known as /dev/sdd)

vmhba0:0:0 /dev/sda

vmhba1:0:0 /dev/sdb

vmhba1:0:1 /dev/sdc

vmhba1:0:2 /dev/sdd

5 Type 'fdisk /dev/sd' where x is the new lun id, eg: fdisk /dev/sdd

6 At the 'Command' prompt, type "u" to change the display units to sectors

7 Type 'p' to display the partition table.

8 Confirm that the 'start' value is set to 128. This means the volume is aligned correctly

9 Type 'q' to quit.

To check windows alignment use diskpar as follows:

1 Type 'diskpar -i #' (where # is the disk number)

2 From the results, confirm that the StartingOffset value of 'drive partition 0 information' has a value of 32768

Cheers

Barry

[lhedrick]

I think this is for 2.5.x ??

For 3.0.x...

For step 1 Use esxcfg-mpath -l

Then followed by the rest...

[esxfan]

Hi,

i tried "fdisk /dev/sdc1", but it shows no 'start' value. What's wrong?

Output:

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 52215.

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): u

Changing display/entry units to sectors

Command (m for help): p

Disk /dev/sdc1: 429.4 GB, 429491154944 bytes

255 heads, 63 sectors/track, 52215 cylinders, total 838849912 sectors

Units = sectors of 1 * 512 = 512 bytes

Device Boot Start End Blocks Id System

Command (m for help):

[mapic]

fdisk /dev/sdc is correct.

sdc1 is the 1st partition of sdc.