Storage Space

[SSDA1296]

In my customer's DC. VMware ESXI hosts connected to a SAN Storage. After some files are deleted in VM, more free space is seen in guest OS's drive. But no free space is increase in SAN Storage's shared LUN. Why and what should I do in which side, at VM or at ESXI or at SAN Storage?

[UZM · Accepted solution]

Thin Provisioning: If your virtual disk is thinly provisioned, the space is only allocated on the SAN storage as the virtual machine writes data. When you delete files, the space is marked as free within the virtual disk, but the SAN may not automatically release that space until you initiate a process called "storage space reclamation.

If it is not enable the automatic space reclamation process in both sides. You need to reclaim in both sides. The SAN's LUN is mounted directly to VM's guest host or mounted to ESXI datastore? 

As per your Storage vendor, SCSI unmap command will a little bit different. You can search with the title "How to SCSI unmap?" or "How to do storage reclamation or reallocation?" like that.

ESXi also supports the reclamation of free space, which is also called the unmap operation. The operation helps the storage array to reclaim unused free space. Unmapped space can be then used for other storage allocation requests and needs. 
You can unmap process in vCenter or in esxcli with the command " esxcli storage vmfs unmap xxxxxx" with specific datastore name that you wish. 

Regards,

[ZawMyint · Accepted solution]

As per my experience in a case, I did space reclamation processes in SAN Storage and VMware. But the space hasn't
increased in Storage's LUN. Therefore, I migrated the VMs to another host in the cluster and rebooted the ESXI host. And then it is work.

If you mounted the LUN directly to the VM's guest OS, please check the OS support or not the SCSI trim/unmap feature.

Best Regards,

[SSDA1296]

Thanks all for your suggestion and solutions. It has already solved as per your suggestion. I really appreciate for your help.

Thanks again,
SSDA

[SSDA1296 · Accepted solution]

Sorry for late reply.

I forward your suggestion to my team, and did the following tasks and done successfully.

1. Performed reclamation process in SAN Storage first.
2.Performed reclamation process in VMware.
3.Wait and observed for 10 minutes above, no free spaces are increased.
4.Migrate the VMs to another Host in the cluster and place the Host in maintenance mode.
5.Reboot the Host.
6.The available space continues to grow and reached within next 30 minutes.

Thanks again for your suggestion.