Microsoft Windows and Long Data Blocks. Steve Jenness Senior Program Manager Microsoft

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1 Microsoft Windows and Long Data Blocks Steve Jenness Senior Program Manager Microsoft

2 Abstract Components throughout the system software changed in Windows Vista and Windows Longhorn Server to support underlying storage that had physical sectors larger than 512 bytes. These components include the software that boot the system, manage volumes, and perform file system I/O. The size of I/O has been adjusted to natively match the physical sector size wherever possible. The alignment of partitions/volumes and file systems have been reworked to optimally match the ondisk alignment of physical sectors. New APIs have been added so that applications can detect the physical and logical sector sizes of the storage under the file system. This allows applications to preserve either the 512 byte blocking factor or the atomicity semantics they have come to expect

3 Windows OS Disk I/O Path Buffered I/O Paged I/O Disk Requests File System Cache Manager Volume Manager Disk Driver UnBuffered I/O Sector I/O

4 Data Path Vista Code through the complete data path was reviewed and updated to support large sector I/O Partitions/volumes are aligned to physical sectors on basic disks Default is to align to 1Mbyte boundaries Vista SP1 and Longhorn Server Partition alignment for dynamic disks Alignment takes into account sector size and LBA 0 offset

5 Data Path (cont d) File System Cluster size is at least physical sector size Cache Management/Memory Mapped I/O Buffered and Unbuffered I/O Going to larger than 4k sector disks will be a another effort Code assumptions about page size >= sector size If drives are behind a RAID controller, Storport doesn t provide offset information

6 Boot Overview BIOS initializes itself Locates disk at BIOS ID 0x80 Finds first sector of this disk and starts executing MBR Boot Code Boot code exists to read the partition table, find first sector of the active partition and start executing it Windows Boot Manager The Boot Manager loads the operating system File System Boot Code/Boot Manager issues I/O calls to the disk based on the sector size reported by Extended Int13/EFI BIOS Once the OS I/O stack is loaded, the previously described data path takes over

7 Applications Are they impacted? If using buffered I/O no impact. If using unbuffered I/O yes; I/O constraints If expecting atomic writes to media yes on 512/4k IOCTL_STORAGE_QUERY_PROPERTY STORAGE_ACCESS_ALIGNMENT_DESCRIPTOR Physical and Logical sector sizes LBA 0 offset Currently works correctly for SATA drives StorPort (SCSI and Arrays) doesn t pass through alignment for SATA arrays

8 Down Level OS Support No changes for pre-vista OS 512/4k disks can be used with the caveat that atomicity is not preserved Backporting IOCTL_STORAGE_QUERY_PROPERTY is under discussion

9 Testing Currently disks are only used as data disks Disks supplied by various vendors 512/4k, 1k, 4k/4k Disks are in various developer s hands VDS test lab runs full test runs on every OS build on all available variants of disks Functional and stress testing; no failure mode testing

10 Summary 1k and 4k disks are working today on Vista and Longhorn Server as data drives If you see problems, please tell us so we can fix it to Get the latest Vista or Longhorn Server release and try it out!

Longhorn Large Sector Size Support. Anuraag Tiwari Program Manager Core File System

Longhorn Large Sector Size Support Anuraag Tiwari Program Manager Core File System anuraagt@microsoft.com Agenda Historical OS Support for Large Sector Size Drives A Brief Overview of the OS Disk I/O Components