VMware Solutions Discussions

mbralign on Linux


I'm attempting to run mbralign on a Linux host against an VMware NFS datastore on a FAS2020.  When I run mbralign against proliant.vmdk, I get the following message:  "failed to open proliant-000001.vmdk with read access".  Any idea what might be causing this?



is the Linux a guest OS here?


To check that your existing partitions are aligned, issue the command: fdisk -lu The output is similar to: Device boot Start End Blocks Id System /dev/sdj1 128 167766794 83883333+ fb Unknown Aligned partitions start at 128. If the Start value is 63 (the default), the partition is not aligned. If you choose not to use the VI Client and create partitions with vmkfstools, or if you want to align the default installation partition before use, take the following steps to use fdisk to align a partition manually from the ESX Server service console: Recommendations for Aligning VMFS Partitions 3 1. Enter fdisk /dev/sd where is the device suffix. 2. Determine if any VMware VMFS partitions already exist. VMware VMFS partitions are identified by a partition system ID of fb. Type d to delete to delete these partitions. Note: This destroys all data currently residing on the VMware VMFS partitions you delete. Ensure you back up this data first if you need it. 3. Type n to create a new partition. 4. Type p to create a primary partition. 5. Type 1 to create partition No. 1. 6. Select the defaults to use the complete disk. 7. Type t to set the partition’s system ID. 8. Type fb to set the partition system ID to fb (VMware VMFS volume). 9. Type x to go into expert mode. 10. Type b to adjust the starting block number. 11. Type 1 to choose partition 1. 12. Type 128 to set it to 128 (the array’s stripe element size). 13. Type w to write label and partition information to disk. A best practice for Linux physical as well as virtual machines is to align file system partitions using fdisk. Use the fdisk procedure in the previous section of this paper, and instead of setting the partition system id to fb, set it to 83 (Linux) or other appropriate partition system ID.


I'm trying to use mbralign on Linux to align a Windows 2003 server VM.


Yes. Linux is a VM running mbralign.


have u tried the diskpart.exe from the windows VM;  by the way i am  little confused with you accepting both Linux and Wndows as VM.  But i am not into vurtualization , so that may be the reason


I will simply use VMware vCenter Converter Standalone Edition 5.0 as it has the capability of aligning disks during V2V processes.

Diskpart can be used to create properly aligned partition for new VMs before installing an OS


Hi doug

your VM machine need to be switched off to be able to run mbralign

Switch off the VM


/opt/netapp/santools/mbralign proliant-000001.vmdk

Then on ESX

To convert to thin again (mbralign do thick only)

vmkfstools -i proliant-000001.vmdk-d thin proliant-000001_temp.vmdk

delete old one

vmkfstools -U proliant-000001.vmdk

rename thin one to original name

vmkfstools -E proliant-000001_temp.vmdk proliant-000001.vmdk

boot your machine

if all good

rm *.vmdk-mbralign-backup

then check your snapshot on the volume as this take a lot of room to do

good luck



Try running mbralign on the same ESX host where your VM resides.


I'm pretty sure I was running it from the same ESX host that the VM resides, but I will verify that.

I have verified that I am running this on the same host as where  my VM resides.


You need to run mbralign and mbrscan against the *-flat.vmdk, that's why you see this error

For anyone that is having issues running mbralign or mbrscan for Windows or Linux, I've created a step by step article on how to do so: http://www.sysadmintutorials.com/tutorials/netapp/netapp-how-to-use-mbralign-to-correct-misalignment/

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