Here I present my latest tool for ESX. An script that automatically converts thick virtual disks to thin.
It has been used for almost a year in my team across different centers and the storage savings are >50%.
Victor was kind enough to create a fork of this program for ESXi. You can find all the info on https://github.com/terreActive/makeThin
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PS: If you link the documentation/script, please link to this post or the blog. The location of the document on the back may change, the blog will not.