[Info-vax] Reclaim disk space for a 3PAR Storage Box

[Michael Moroney]

On 8/27/2021 8:50 AM, Bruno Seghers wrote:
> Dear all,
> I would like to expose you an issue with the hope that you can help me to solve it in the best way.
> 
> We have OpenVMS 8.4 clusters connected to a full SSD 3PAR storage box via a FC SAN.

HPE 8.4 or a VSI version?
> 
> We have thin provisioning activated on the 3PAR meaning that we make some “overbooking” with the disk size. We can’t have all disks presented with 100% used space because we don’t have that physical disk space available.

VMS does not know about thin provisioning, and while it will happily 
grab space from the storage controller, it has no way to tell it to give 
it back.  VMS doesn't use the "trim" function needed.

This is item #1,724,764,331 of about 5,382,118,992 things that need to 
be added to VMS but which VSI simply doesn't have the resources to do.

Expect to get some sort of error from the storage controller when it 
tries to tell VMS 100% of the existing space has been used, even though 
VMS may be trying to create a file on a disk with "plenty" of free 
space. This could get ugly.

Maybe, just maybe, a storage controller may consider a huge chunk of 
zeroed disk space as having been released. But I doubt it.