PetervandenBosc
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Disk Alignment errors NettApp

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One off my costumers had performence issues, NettApp did research and found out that there are some Disk Alignment issues. What causes this issues? How can i make sure this never happens again?

regards, Peter van den Bosch

regards, Peter van den Bosch Usefull? Award me a few points πŸ˜‰
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depping
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You should align the VMFS normally and the NTFS disk/partition(the vmdk, should be the same as the windows disk). Normally VMFS is aligned automatically, but ntfs isn't. You can realign the ntfs partitions them with mbralign... but it takes time,



Duncan

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Texiwill
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Hello,

Moved to Enterprise Strategy and Planning forum.

to determine if your LUNs are aligned properly read http://www.vmware.com/pdf/esx3_partition_align.pdf which are instructions for EMC, you really need the values for NetApp's LUN alignment.


Best regards,

Edward L. Haletky

VMware Communities User Moderator

====

Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education.

CIO Virtualization Blog: http://www.cio.com/blog/index/topic/168354

As well as the Virtualization Wiki at http://www.astroarch.com/wiki/index.php/Virtualization

--
Edward L. Haletky
vExpert XIII: 2009-2021,
VMTN Community Moderator
vSphere Upgrade Saga: https://www.astroarch.com/blogs
GitHub Repo: https://github.com/Texiwill
depping
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How were the VMFS's created? Via the command line or thru VC?




Duncan

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PetervandenBosc
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Texiwill Thnxs!

i know how to solve the aligment errors but i want to know what caused it...






regards, Peter van den Bosch

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PetervandenBosc
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Hallo Duncan,

all VMFS partitions were created thru VC.






regards, Peter van den Bosch

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depping
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Are we talking about NFS or VMFS? NetApp also used the default 64K boundary so it should be correct when created via the VC. Are we talking about SAN LUN alignment or VM Disk alignment, which could also be of...



Duncan

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PetervandenBosc
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Duncan,

Two issues, some fragmentation on the WAFL file system and this:

# ./mbrscan /vmfs/volumes/48b55c9f-c7ad9458-5b6f-001cc4470925/S-DAOR09/S-DAOR09-flat.vmdk

/vmfs/volumes/48b55c9f-c7ad9458-5b6f-001cc4470925/S-DAOR09/S-DAOR09-flat.vmdk p1 (NTFS) lba: 63 offset:32256 aligned: No

This errors came up with several VMDK disks we are talking about VMFS.

Also this error on the VMFS LUN:

lun:/vol/VMFS_GH_03/vmfs_gh_03.lun-C5BuV4KFxdFT:read_align_histo.7:88% (should be 0%)






regards, Peter van den Bosch

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RParker
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> (NTFS) lba: 63 offset:32256 aligned: No

It's not necessary to align every VM, only VM's with HIGH IO. There is also some question on whether or not alignment does anything. We have Netapp (3070), attach via Fiber, and we did a disk align on some high IO VM's. Before and after we saw ZERO performance change. So that is a waste of my time, and I did align my templates, so I am not worried about current VM's, future VM's will be aligned, for whatever that's worth.

Also do you have mbralign? You need to shut down the VM first to do it, and the process takes about an hour PER VM. It's painful.

Then the WAFL needs minimum 20% free on the volumes to scrub the disks, normally done on Sunday. If you manage aggregrates, you can visually see if disk scrub is active and what percentage of the scrub was completed. That may be part of your problem.

> lun:/vol/VMFS_GH_03/vmfs_gh_03.lun-C5BuV4KFxdFT:read_align_histo.7:88% (should be 0%)

Where is this coming from? A log file?

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PetervandenBosc
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Data ONTAP 7.2.1 added a section into stats stop -I perfstat_lun that makes it very easy to detect unaligned I/O. Simply find the LUN you are interested in and review the "read_align_histo" and "write_align_histo" histograms. Any non-zero value in any of the histogram lines except "read_align_histo.0" and "write_align_histo.0" indicate some misaligned I/O.






regards, Peter van den Bosch

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depping
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the default for ntfs is 63, so it seems like the OS hasn't been aligned properly.



Duncan

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PetervandenBosc
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So should i align the VMDK or de NTFS partition or the LUN? Or all....




regards, Peter van den Bosch

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depping
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You should align the VMFS normally and the NTFS disk/partition(the vmdk, should be the same as the windows disk). Normally VMFS is aligned automatically, but ntfs isn't. You can realign the ntfs partitions them with mbralign... but it takes time,



Duncan

Blogging: http://www.yellow-bricks.com

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PetervandenBosc
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Duncan,

THNXS! VMware made a good choice hiring you Smiley Wink Kudo's for you!






regards, Peter van den Bosch

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depping
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No problem, and I've been looking for the mbralign and mbrscan tools myself but the original link has been removed from the netapp website, do you perhaps have a new link? Or if you have both tools or the tool set maybe you can email me them?



Duncan

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RParker
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Send me a private message with your email, and I can send them to you. I have both of them. I don't have the link, just the actually files.

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mayse
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hello,

i have issue with vmdk alignment, and i can't find anywhere the mbralign tool, could you send it to me?

thanks

best regards

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GDeards
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My apologies if I am making this request in the wrong area. I am new to teh VMware community.

I too have been looking everywhere for the MBRALIGN and MBRTOOLS packages with no luck. Is it possible to send me the tools or a link to them. I appreciate any assistance in obtaining the tools.

Regards, Grahame Deards

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bertdb
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those would be NetApp-specific tools, right ? If so, I suggest you ask NetApp about them.

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omair
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Hi,

Is it posible if you can send me mbralign an mbrscan tools.

Let me know if its OK.... I will then send you a private message with my e-mail address.

Cheers,

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meistermn
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Microsoft suggest 2048 offset, same as for windows 2008 !!!

commands:

create partition primary align=1024

wmic partition get BlockSize, StartingOffset, Name, Index

http://support.microsoft.com/kb/929491/en-us

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