IBM XIV Storage System and Windows Server 2012 thin provisioned drives
HenryLSautter 060000A1C6 Visits (4492)
Thin Provisioning provides a volume size as specified but uses physical storage only when needed. While this sounds like a great way to efficiently use the available storage space, in real life situations this may not always be true. When files are deleted or moved the now unused data is usually still residing on the physical storage. The host system may indicate that the used capacity is now smaller but the physical storage is still in use and remains allocated to that host system.
Space reclamation deals with this situation by providing a way for the host system to indicate that the physical storage assigned to it is no longer in use. space reclamation in operating systems are typically achieved by invoking the Small Computer System Interface (SCSI) WRITE SAME or the SCSI UNMAP command. Which commands are used depends on the operating system involved.
Starting with the XIV Storage Software v11.2, the XIV Storage System Gen3 provides support for the SCSI UNMAP function, natively available with Microsoft Windows Server 2012, automatically enabling Space Recl
The space reclamation happens automatically. When a file is deleted the XIV storage system is notified and the space is marked as "not in use", making it available for other servers if needed.
Setup of this feature happens when the XIV Host Attachment Kit is run to connect the Server to the IBM XIV Storage System.
Windows Server 2012 then recognizes the new disk as a thin provisioned drive.
Considerations for using Thin Provisioning with Microsoft Windows 2012 are summarized in th
We have a draft RedPaper (REDP-5001) in preparation that will provide all the details.
I will update this post as soon as the draft is released.