Changing Block Size from 1MB to (4MB or 8MB)

[Dan_Lein]

Hello all,

I am in a delemia.  I have an ESXi vSphere 4.1 installed but I used the default 1MB block size when isstalling ESXi.  I have been running Virtual Machines for quite some time on it and cannot simply re-install the ESXi again.  I am currently in need of larger than 256GB drives in my virtual machines.

What I have read for possible fixes for changing the datastore from 1MB to 4MB or 8MB to support disks larger than 256GB is to add in new temporary HDD into the server and create a new datastore on it with 4MB or 8MB block size and then migrate the virtual machines over to the new larger block size datastore.  Then re-initialize the original 1MB datastore as a 4MB or 8MB and migrate back to the original datastore.

Two questions on this:

1)  Is my detailed fix possible?  That is, can I add another, say, 8MB block size datastore, even though I set up the ESXi server as a 1MB? Or will it just automatically initiaize the new temporary datastore as 1MB no matter what?

2) If this fix is possible, will the move of the virtual machines from a 1MB datastore to a 8MB datastore have reprecussions?  That is, does moving a Virtual Machine with block size 1MB to a datastore with 8MB cause problems with that virtual machine?

Any suggestions would be great.

Thanks in advance.

-Dan

[a_p_ · Accepted solution]

Welcome to the Community,

you can format each datastore (which is just a partition with a partition type VMFS) with a different block size and move the VM's back and forth if you like. However, if your hardware supports ESXi 5.x this may be an easier way to solve the dilemma, because after upgrading to ESXi 5.x you can also upgrade the datastore from VMFS3 to VMFS5 which supports file (virtual disk) sizes of up to ~2TB with a unified 1MB block size.

André

[Dan_Lein]

Thank you for the quick response Andre,

Yes, I believe that an upgrade would be the best option for me if I can keep everything the same and gain the ability to go to 2TB virtual disks.  Will the virtual machines just inherit the ability to go to 2TB when I perform the ESXi 5.1 upgrade and perform the VMFS5 upgrade?

[a_p_]

Yes, after upgrading to ESXi 5 you only need to go to "Configuration" -> "Storage", select the datastore and click the "Upgrade to VMFS5..." link. As soon as this is done (only requires a few seconds) you can take advantage of the new file system features.

André

[Dan_Lein]

Thank you so much Andre.  I will have to try this as it does seem like the most straight-forward way around my current problem.

[a_p_]

Although the upgrade is usually a pretty straight forward process, consider to backup your data before upgrading. Just in case something unexpected happens.

André