Grow hard disk for vm fails but VI client reports operation successful

[VirtualTman]

I tried to grow a 1TB drive by 100GB on a 8mb block size LUN that had 117GB of free space still. I thought 17GB free space would be adequate.

I got an operation completed successfully task in VI Client after resizing this vmdk by 100GB, YET no actual changes were made.

I tried again by increasing it by 50GB (with 117GB free) and same result.

Only when I tried to increase it by 20GB, then it worked fine.

QUESTION:

What percentage of disk space must be available on the LUN to grow a 1TB vmdk? Is it a percentage of the vmdk file?

Why would VI Client report a successful operation, yet no change occurred?

Your help is most appreciated.

Thanks

[ananthss]

I'm also facing the same issue, but i have only maximum size as 91.38 GB and free space is free space only 48 GB and trying to increase 40 GB or 20 GB or even 1 GB its not working. There is not error also. it not applying.

If i want to do it by vmware-vdiskmanager command, i dont have this command in my client system where i have installed VMWare infrastructure client

how do i resolve this issue, can anyone help us here

Ananth

[bobross · Accepted solution]

Bottom line first: you're not going to be able to overcome it easily.

The reason is the large blocksize. If you choose 8MB blocks, that's fine, but the tradeoff is that even if a sub-block is used, the entire block is considered unavailable for growth. So, you have wasted space in many of your 8MB blocks. It's counted as free, so you think you have enough free space to grow, but in reality there are very few if any blocks that are completely empty. Unfortunately, there is no easy way to 'squeeze' the blocks and/or move the white space into 'clean' blocks for growth.

Many folks think 8MB is the way to go, and use it all the time. Not so. As with most things, there are space-time tradeoffs. I personally use 1MB as a size; it's a good 'medium' choice, balancing free space and overhead.

For me as well, I don't have to worry about growing VMFS, because if my datastore starts to get full, I just grow it on the fly with my Xiotech. Don't have to use VI at all.