Is there an easy way to align the C: drive on a windows system? I have
gone through the process using a helper VM to partition and format the
VMDK and then install the OS on the newly-formatted disk, but there
must be a better way. Is it really necessary?

Dave Convery
VMware vExpert 2009
http://www.dailyhypervisor.com

Careful. We don't want to learn from this.
Bill Watterson, "Calvin and Hobbes"

I actually have nothing to add, but wanted to at least say great thread! Should make all people looking to post to the communities read this first. Will solve a lot of issues and have good information concearning the typical IO testing for vmware (using raw storage with iometer). Also, still a lot of people do not know about alignment issues with vmfs. Again, this would be a great intro post for VMware and storage

Kevin Goodman
kevin@colovirt.com
http://blog.colovirt.com

there's no point in aligning your C:\ drive unless you have a lot of data traffic on the C:\ which is unlikely. The mbr-tools by NetApp could do this indeed.

Duncan
VMware Communities User Moderator | VCP | VCDX

---

Blogging: http://www.yellow-bricks.com
Twitter: http://www.twitter.com/depping

If you find this information useful, please award points for "correct" or "helpful".

Sometimes (most of the time) after running NetApp's MBRALIGN on Linux VMs, the VM is no longer bootable. It will immediately hang at a GRUB prompt. There is a repair procedure that involves booting from a Knoppix CD and running a few commands to repair the boot loader of the affected Linux VM. I've been through it dozens of time. Once the boot loader is repaired, the Linux VM will boot and its partitions will be aligned. I have seen rare cases where the fix does not actually work and you have no choice but to revert to the backed up .vmdk files that mbralign automatically creates for you. At that point, you can try the align process again or give up. The align process takes a while and it varies upon how large each .vmdk file is of course. On average what I see is an alignment of a 50GB .vmdk file in half an hour or less.

• Once the knoppix CDROM has booted, From the 'boot>' prompt type 'knoppix 2' and hit RETURN

• From the Command Line, type 'grub' to get to the grub prompt

• Run "find /boot/grub/stage1" and note all of the drives it finds (e.g., "(hd0,0)")

• From the GRUB prompt, for each Drive, Run the following:

grub> find /boot/grub/stage1
(hd0,0)
(hd1,0)
(hd2,0)

grub> root (hd0,0)
Filesystem type is ext2fs, partition type 0x83

grub> setup (hd0)
Checking if "/boot/grub/stage1" exists... yes
Checking if "/boot/grub/stage2" exists... yes
Checking if "/boot/grub/e2fs_stage1_5" exists... yes
Running "embed /boot/grub/e2fs_stage1_5 (hd0)"... 15 sectors are embedded.
succeeded
Running "install /boot/grub/stage1 (hd0) (hd0)1+15 p (hd0,0)/boot/grub/stage2 /boot/grub/menu.lst"... succeeded
Done.

grub>

• You can batch process multiple boot drives, just attach all of the drives you wish to fix to a dedicated knoppix appliance that boots from the Knoppix CD.

You should be able to download the NetApp tools. Just go create yourself a now.netapp.com account and download the mbrscan and mbralign tools
http://communities.netapp.com/docs/DOC-2563;jsessionid=3FAC4EB6245FD8344D98EA9247C2FE34

Don't forget that MBRALIGN creates backups of your .vmdk files which will chew up double the amount of storage you use so go back and delete those backup files once you've determined the alignment is a success.

I align all drives as a best practice. Not as a performance benefit for the individual VM, but as a performance benefit for the storage array that all VMs point back to. Disk alignment converts all unaligned disk I/Os from a maximum possible value of 2 IOs to a value of 1 IO. If you multiply that factor by hundreds or thousands you start to see a little performance increase for the VMs. Now multiple that savings by X number of VMs on each LUN, disk group, etc. and you might see how aligning C: drives collectively improves the maximum amount of performance you can squeeze out of that LUN, disk group, storage array, etc. This is an example of where the value of the savings is greater than the sum of all of its parts.






Jason Boche, vExpert
boche.net - VMware Virtualization Evangelist
VMware Communities User Moderator
Minneapolis Area VMware User Group Leader

I have aligned the system partition (and created a template from an aligned VM) in the past as well. I have even written an article on it. Then it occured to me after reading the VMware whitepaper again that I must be missing something. Why does this question (how to align C: drives) keep coming up when the VMware whitepaper on partition alignment has this note:

Note: Aligning the boot disk in the virtual machine is neither recommended nor required.
Align only the data disks in the virtual machine.
The following sections discuss how to align guest operating system partitions in Linux and
Windows environments.

What am I missing guys? I found another thread (can't find it at the moment) claiming that aligned C: drives may cause problems with VSS on certain arrays. Is this true? Does anyone know what arrays have this issue? Should the best practice going forward be to not align the C: drive at all because of the note in the VMware whitepaper? I know I have more questions than answers. I am just trying to get to the bottom of this.

Don't forget to use the buttons on the side to award points if you found this useful (you'll get points too).

Regards,

Harley Stagner

Reading the instructions for MBRALIGN, it notes with Linux and Solaris running GRUB there may be issues on bootup. The instructions are quite clear on how to remedy this for Linux (as well as documented here), but they leave out the analogous step-by-step instructions for Solaris.

So, the question I have is, has anyone used MBRALIGN on a Solaris 10 VM and what were the caviates and solutions to such issues?

Charlie

Hello za_mkh,

I did write an article on this in January.

http://searchvmware.techtarget.com/tip/0,289483,sid179_gci1344730_mem1,00.html

Basically, I used a WinPE disk to align a system partition, then I created a template. Every VM cloned from that template will be aligned.

However: Now I question whether this should be done. As I said above, this note is in the Disk Alignment whitepaper from VMware:

Note: Aligning the boot disk in the virtual machine is neither recommended nor required.
* Align only the data disks in the virtual machine.*

I hope this helps.

Don't forget to use the buttons on the side to award points if you found this useful (you'll get points too).

Regards,

Harley Stagner

So...Since VI3 anly aligns VMFS when created via the VIC, how about ESX4? This requires a VMFS on install for the COS VM. Is it aligned?

Dave Convery
VMware vExpert 2009
http://www.dailyhypervisor.com
http://twitter.com/dconvery

Careful. We don't want to learn from this.
Bill Watterson, "Calvin and Hobbes"