I can see the lun used capcity level difference in storage and host, I can see a lun is used upto 100% in HUS VM and the same is just used 45% in host. please let me know the procedure to reclaim the zero pages.
I'll answer your question in two parts and i think #2 is what you are looking for:
#1 - All Zero pages can be reclaimed by issuing aZPR on the DP VOL. Note that ZPR will not zero out a page but will only look for pages that are already 'all Zeroes' and reclaim these pages.
#2 - HUSVM supports space reclamation in a RHEL environment using the Discard or fstrimoption. Please make sure HMO68 is ON. Using either of these two cammands will allow you to reclaim capacity deleted by the host (not necessarily 'all zero' pages on storage).
Red Hat support storage thin reclamation for ext4 and XFS filesystems. Discard unused blocks are supported on ext4 file systems as of Red Hat Enterprise Linux 6.2 and later, and on XFS file systems as of Red Hat Enterprise Linux 6.4 and later.
Discard requests are issued to the storage using the negotiated discard command specific to the storage protocol (TRIM command for ATA, and WRITE SAME with UNMAP set, or UNMAP command for SCSI).
Storage space reclamation on RHEL can be done by two methods (a) batch discard and (b) online discard.
1. Use fstrim command on mount point (batch discard)
# fstrim -v /mount_point
2. Mount filesystem with discard option (either in /etc/fstab or as part of the mount command) (online discard). Online discard operations run in realtime without user intervention. Online discard operations only discard blocks that are transitioning from used to free.
# mount -o discard /dev/sda1 /mount_point
Entry in /etc/fstab,
# cat /etc/fstab
/dev/sda1 /fs0 ext4 defaults,discard 0 2
Physical discard operations are supported if the value of /sys/block/device/queue/discard_m ax_bytes is not zero.
Red Hat recommends batch discard operations unless the system's workload is such that batch discard is not feasible, or online discard operations are necessary to maintain performance.
It is also a best practice to issue a ZPR once host based reclamationis complete. This is to insure that no Zero'ed out page is left behind.
Retrieving data ...